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Oncology- Palliative Surgery
I. Core Principles of Palliative Surgery
  • Timing is Crucial: The decision to operate is paramount. The adage "Good surgeons know how to operate; better ones when to operate; the best when not to operate" highlights the importance of considering a patient's life expectancy and overall condition. Multidisciplinary team discussions are essential.
  • Individualized Approach: The optimal procedure varies widely depending on the patient's specific circumstances and tumor characteristics.
II. Specific Palliative Procedures
A. Bowel Obstruction
  • Causes: Most commonly arises from colon cancer, due to resectable tumors or advanced pelvic masses. Ovarian cancer can also cause obstruction.
  • Management:
    • Resectable tumors: Surgical resection is ideal.
    • Inoperable tumors:
      • Colostomy/Ileostomy: Decompresses the bowel.
      • Endoscopic stent placement (left-sided tumors): A less invasive option, but carries a 4% perforation and 12% migration risk.
    • Ovarian cancer: Debulking surgery (often combined with chemotherapy) may provide good long-term palliation in suitable patients.
    • Multiple obstruction sites: Often difficult to manage surgically; internal bypass or proximal stoma may be options, but surgery isn't always feasible.
B. Fistulae
  • Causes: Direct tumor invasion or post-radiotherapy complications (especially with pelvic tumors).
  • Types: Rectovaginal, enterovaginal, colovesical, vesicovaginal, enteroenteric, enterocutaneous.
  • Management: Preoperative assessment is crucial. If definitive surgery isn't possible, a proximal end stoma is the preferred treatment to minimize distress. Endoscopic covered stents can be used for colovesical fistulae.
C. Jaundice
  • Management:
    • Endoscopic Stenting (ERCP): Primary method for periampullary lesions. Percutaneous transhepatic cholangiography (PTC) may be necessary for hilar cholangiocarcinomas, sometimes in conjunction with ERCP. Metallic stents are preferred for survival >3 months.
    • Operative Options (Hepatojejunostomy/Choledochojejunostomy): Less common due to endoscopic stenting, but regaining popularity via laparoscopic techniques due to shorter hospital stays and reduced morbidity compared to endoscopic stenting. Segment III biliary enteric bypass for selected inoperable hilar tumors. Requires hepato-pancreato-biliary (HPB) MDT discussion.
D. Ascites
  • Management: Sodium restriction, diuresis, serial paracentesis are first-line treatments.
  • Refractory Cases: Peritoneal drain or a peritoneal-venous shunt (Le Veen or Denver) may provide relief, particularly for ovarian or breast cancer. Less effective for GI malignancies. Assess for loculated ascites and mucinous tumors (risk of rapid shunt occlusion).
E. Pain
  • Management: Requires collaboration with palliative care. Surgical options include:
    • Debulking: For large, slow-growing tumors in fit patients.
    • Fracture Stabilization: Prophylactic pinning for bone metastases affecting >50% of the cortex.
    • Neurosurgical Approaches (rare): Cordotomy is rarely used now due to advancements in analgesia.
    • Thoracoscopic Splanchnectomy (rare): For intractable pancreatic cancer pain, largely replaced by EUS-guided coeliac plexus blocks.
F. Gastrointestinal Bleeding
  • Management: Endoscopic and radiological techniques (injection sclerotherapy, laser coagulation, arteriographic embolization) are initial treatments. Surgery is considered only if other methods fail and life expectancy is ≥3 months.
G. Cytoreductive Surgery
  • Partial resection: Appropriate when complete removal of disease is not possible, particularly in ovarian cancer, to improve outcomes with subsequent chemotherapy.
H. Palliative Resection of Primary Tumor
  • Breast Cancer: Resection may improve quality of life (QoL) by preventing fungation or uncontrolled axillary metastases, especially in patients with bone metastases (median survival >2 years).
  • Gastric Cancer: Considered for outlet obstruction or persistent anemia despite transfusions.
  • Colorectal Cancer: May be considered even with inoperable liver metastases to reduce bleeding, perforation, or obstruction risk.
I. Minimally Invasive Techniques: Laparoscopic surgery is increasingly used for many palliative procedures, reducing morbidity and improving QoL.
III. Key Terms
  • Palliation: Relieving symptoms and improving quality of life without aiming for a cure.
  • Debulking: Surgical removal of as much of a tumor as possible.
  • ERCP (Endoscopic Retrograde Cholangiopancreatography): Endoscopic procedure to visualize and treat biliary and pancreatic ducts.
  • PTC (Percutaneous Transhepatic Cholangiography): A procedure to visualize the biliary system via a needle inserted through the skin and liver.
  • MDT (Multidisciplinary Team): A team of specialists (surgeons, oncologists, radiologists, etc.) working together to plan patient care.
  • Co-morbidities: The presence of one or more additional diseases or conditions in a patient.​
  • QoL (Quality of Life): A subjective assessment of a patient’s overall well-being.
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Oncology-Brachytherapy
I. Definition and Indications:
  • Brachytherapy: Radiation therapy where sources are placed within or near the tumor. Crucially, precise tumor extent is vital because treatment targets a small volume, and missing the tumor (geographic miss) significantly increases recurrence risk. Accessibility for source insertion and removal, along with accurate source positioning, is also crucial.
II. Advantages:
  • High Localized Dose: Delivers a high dose to a small area, maximizing local tumor control while minimizing damage to surrounding normal tissue due to the sharp fall-off of radiation dose.
  • Short Treatment Duration (2-7 days): Uses low-dose-rate irradiation, leveraging the differing repair/repopulation rates of normal and malignant cells for enhanced therapeutic ratio. This also allows for reoxygenation of initially resistant hypoxic cells, increasing their radiosensitivity.
  • Compensation for Hypoxic Cells: Higher doses in the tumor center (near sources) help overcome the radioresistance of hypoxic cells often found in avascular/necrotic areas.
  • Irregular Tumor Treatment: Allows for treatment of irregularly shaped tumors by precise source placement, avoiding critical normal tissues.
III. Disadvantages:
  • Staff Radiation Exposure: γ-emitting sources expose staff to low but significant radiation. Afterloading techniques and low-energy radionuclides mitigate this risk.
  • Unsuitable for Large Tumors: Typically not suitable for large tumors; may be used as a boost after external beam radiotherapy (EBRT) and/or chemotherapy.
  • Accurate Source Positioning Crucial: Dose falls off rapidly (inverse square law), requiring precise source placement. This demands specialized skill and is not universally available.
  • Limited Treatment Volume: Surrounding structures (e.g., lymph nodes) are not irradiated.
IV. Types of Brachytherapy:
  • Intracavity: Radioactive material placed within body cavities (e.g., cervix, bronchus, esophagus, bile duct).
  • Interstitial: Radioactive material inserted into tissues (e.g., prostate, breast, head & neck, anal).
  • Surface: Radioactive material placed on the tumor surface (e.g., skin, eye).
V. Implant Types:
  • Manual Insertion: Should be avoided due to radiation hazards to staff.
  • Afterloading: Radioactive material loaded into pre-inserted applicators (needles, catheters). Reduces staff exposure significantly, allowing for optimal source placement.
    • Manual Afterloading: Radioactive material manually loaded into applicators.
    • Remote Afterloading: Machines (e.g., Selectron, Microselectron, Cathetron) control source placement, eliminating staff exposure. High-dose-rate remote afterloading often involves multiple outpatient fractions.
VI. Radionuclides:
  • γ Emitters:
    • Radium: Obsolete; radon gas is a hazard.
    • Cesium-137: Replaces radium; longer half-life (30 years), less penetrating γ rays.
    • Iridium-192: Used in wires or seeds; flexible, advantages in interstitial brachytherapy; shorter half-life (74 days).
    • Iodine-125: Used for permanent prostate implants; short half-life (59.6 days), low-energy γ rays allow for early discharge.
  • β Emitters: Primarily used in eye tumor treatment (strontium-90, ruthenium-106/rhodium-106 plaques).
VII. Dosimetry:
  • Treatment Planning Systems: Various systems (Paris system, Parker-Paterson, Quimby) are used to plan source distribution. The Paris system, common for iridium wire implants, uses parallel, equidistant wires. Computer calculations and graphs (Oxford cross-line curves) assist in dose calculation.
  • Dose Prescription: The basal dose rate (mean of minimum values between sources) is calculated. Treatment dose is prescribed to a reference dose line (often 85% of basal dose). Prescription points vary depending on the treatment type (e.g., Manchester A point for gynecological treatments). The ICRU Report 38 recommends reporting dose based on the volume enclosed by a 60Gy isodose line in gynecological treatments.
VIII. Future Developments:
  • 3D Planning: Sophisticated 3D planning using CT or MRI scans for precise dose calculations.
  • Biological Effective Dose: Incorporating biological effects in dose calculations.
  • High-Dose-Rate Remote Afterloading: Continues to reduce staff exposure and improve treatment outcomes. High-dose-rate pulsed insertions are increasingly replacing continuous low-dose-rate implants for greater homogeneity.
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Oncology- Electron Beam Therapy
I. Electron Beam Therapy vs. Photon Radiotherapy
A. Fundamental Difference: Electron beams, unlike photons, possess charge. This leads to frequent interactions within tissue, resulting in a defined range of penetration and negligible dose beyond that range. Photons penetrate deeper.
B. Electron Beam Advantages:
  • Limited penetration: Ideal for superficial tumors, minimizing damage to underlying structures.
  • Negligible exit dose: Reduces radiation exposure to tissues beyond the target.
  • Superficial tumor treatment: Particularly useful for skin cancer, head and neck cancers, and breast cancer.
  • Reduced normal tissue dose: Minimizes damage to critical structures like the spinal cord and lungs.
C. Photon Beam Advantages:
  • Deep penetration: Suitable for deep-seated cancers.
  • Skin sparing: Delivers less radiation to the skin surface.
  • Easier beam matching: Facilitates precise treatment planning with crossfire techniques.
II. Production of Electron Beams
  • Linear Accelerators: Most radiotherapy facilities use linear accelerators to produce both X-ray and electron beams.
  • Beam Collimation: Due to significant air scattering, collimators (cones or trimmer bars) are used to shape the beam near the skin's surface. Further shaping can be achieved with lead apertures or lead sheets placed directly on the skin.
III. Dosimetric Characteristics of Electron Beams
A. Depth Dose Characteristics:
  • Dose buildup: The dose increases gradually to a maximum and then drops sharply to near zero at the practical range.
  • Practical Range (Rp): The depth at which the dose becomes negligible. Approximated by Rp ≈ E0 / 2. (E0 = incident beam energy in MeV)
  • Clinically Useful Range (d80): The depth where the dose falls to 80% of its maximum. Approximated by d80 ≈ E0 / 3.
  • Surface Dose: Significantly higher for electron beams than photon beams (85-95% of maximum dose, depending on energy).
B. Effect of Incident Energy: Higher incident energy (E0) leads to greater penetration depth. Common energies range from 6-15 MeV.
C. Beam Profile and Penumbra:
  • Larger Penumbra: Electron beams have a larger penumbra (area of dose falloff) than photon beams. A 10x10 cm² beam might only deliver a clinically useful dose to an 8x8 cm² area.
  • Abutment Challenges: The large penumbra makes combining electron and photon beams difficult, hindering uniform dose delivery across field junctions.
IV. Key Concepts to Remember
  • Charge and Interaction: Electrons' charge leads to their limited penetration and well-defined range.
  • Superficial vs. Deep: Electron beams are for superficial tumors, photons for deep-seated ones.
  • Penumbra: Electron beams have a larger penumbra than photon beams, affecting treatment planning.
  • Range Calculation: Understand the approximations for practical and clinically useful range based on incident energy.
  • Surface Dose: Electron beams have a higher surface dose than photon beams.



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Oncology-Recent Advances in External Beam Radiotherapy (EBRT)
I. Improved Accuracy and Precision
A. Volume Definition:
  • Past: Planning scans relied on diagnostic scanners, resulting in less precise tumor volume definition.
  • Present: High-resolution CT simulators are standard. 3D tumor volume definition is now accurate even for palliative treatments. Fusion of CT with MRI and PET scans further refines this for radical treatments.
B. Image-Guided Radiotherapy (IGRT):
  • Past: A 1cm margin was added to the Clinical Target Volume (CTV) to account for positioning errors. Megavoltage X-rays provided low-quality confirmation images.
  • Present:
    • Electronic Portal Imaging Devices (EPIDs): Replaced port films, offering improved image quality. Online imaging corrects misalignments before treatment, while offline review identifies recurring setup errors.
    • Intra-treatment Imaging: Precise tumor location is confirmed during treatment using:
      • Fiducial markers (e.g., gold seeds)
      • Ultrasound
      • Cone beam CT (mounted on the linear accelerator) for 3D online imaging.
II. Minimizing Radiation Exposure to Organs at Risk & Higher Tumor Doses
A. Inverse Planned Intensity-Modulated Radiotherapy (IMRT):
  • Mechanism: Computer optimization varies radiation beam intensity to meet dose constraints for healthy organs while delivering prescribed doses to the tumor (CTV and Gross Tumor Volume - GTV). This is achieved through:
    • Step and shoot: Superimposing static uniform intensity segments.
    • Dynamic MLC delivery: A shaped sliding window across the field.
    • Tomotherapy: Multiple arcs with intensity modulated by dynamic MLCs.
  • Benefits: Reduced late effects on normal tissues with equivalent cancer control compared to conventional radiotherapy, particularly in prostate and head/neck cancers. Promising results in lung and gynecological cancers suggest it may replace 3D conformal radiotherapy (CRT) for many radical treatments.
  • Drawback: Significantly increases the workload of the physics team due to the extensive time (at least 2 hours per patient) required for meticulous volume definition.
B. Four-Dimensional (4D) Therapy Planning and Delivery:
  • Addresses the challenge of: Treating mobile structures (e.g., lung cancers moving with respiration).
  • Method: Links 4D CT planning (tumor volume defined at each respiratory phase) to treatment delivery during the expiratory phase for optimal coverage with minimal field size.
C. Stereotactic Radiotherapy:
  • Established for: Intracranial conditions (benign tumors, arteriovenous malformations).
  • Method: High precision (1-2mm) treatment of small lesions (<1cm3) using an external 3d coordinate system and stereotactic fixation. typically uses 1-3 large fractions (12-20 gy).< />pan>
  • Recent expansion: Successful treatment of small malignancies in the brain, lung, and liver. IGRT facilitates accuracy in sites unsuitable for localization frames.
III. Key Terms & Concepts to Remember:
  • CTV: Clinical Target Volume
  • GTV: Gross Tumor Volume
  • EPID: Electronic Portal Imaging Device
  • IMRT: Intensity-Modulated Radiotherapy
  • MLC: Multileaf Collimator
  • IGRT: Image-Guided Radiotherapy
  • 4D: Four-Dimensional (referring to respiratory gating)
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Oncology-External Beam Radiotherapy: Progress & Techniques
This study guide summarizes advancements in external beam radiotherapy, focusing on 3D planning and conformal treatment.
I. Three-Dimensional (3D) Radiotherapy Planning:
  • Revolutionizing Factor: The most significant advancement in the last 20 years is the integration of cross-sectional imaging (primarily CT scans) into radiotherapy planning. This shift enables:
    • Accurate Target Definition: Precise delineation of tumors and critical structures.
    • Precise Dose Calculation: More accurate determination of radiation dosage.
    • True 3D Planning: Allows for:
      • Reduced Normal Tissue Damage: Minimizing harm to healthy tissue.
      • Increased Tumor Dose: Delivering higher radiation doses to the cancerous target.
      • Improved Therapeutic Index: Optimizing the balance between tumor control and side effects.
Key takeaway: 3D planning using CT scans significantly improves accuracy and allows for better treatment optimization, leading to improved outcomes.
II. Conformal Treatment and Multileaf Collimators (MLCs):
  • Goal: The primary goal of radiotherapy has always been to precisely conform the high-dose radiation to the target tumor while sparing surrounding healthy tissue.
  • Traditional Limitations: Until the 1990s, rectangular beams with limited blocking techniques resulted in unnecessary irradiation of normal tissue.
  • Advancements:
    • Shaped Alloy Blocks: Improved conformation by manually placing shaped blocks to partially obstruct the radiation beam.
    • Multileaf Collimators (MLCs): A significant advancement integrated into modern linear accelerators. MLCs allow for computer-controlled shaping of the radiation beam using numerous 0.5cm-wide leaves. This enables highly precise shaping of the radiation field.
  • Clinical Significance: By minimizing high-dose radiation to normal tissue, MLCs enable higher radiation doses to the tumor, potentially improving tumor control without increasing the risk of side effects (morbidity).
Key takeaway: MLCs are a crucial technology for conformal radiotherapy. They allow for precise shaping of the radiation beam, maximizing tumor dose while minimizing damage to healthy tissues. This improves the therapeutic ratio, aiming for better tumor control with fewer side effects.


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Pathology-External Beam Radiotherapy (EBRT)
I. Types of EBRT
A. Superficial X-ray Therapy (80-300 kV): Used for superficial tumors (skin, ribs). Low-energy X-rays are generated by accelerating electrons in an X-ray tube, which then strike a tungsten anode causing bremsstrahlung radiation. Beam size is controlled by metal applicators.
B. Cobalt Teletherapy (Co-60): Uses gamma rays (1.25 MeV average energy) from Co-60 source for deeper tumors. Requires high source strength (around 350 TBq) for adequate dose rate.
C. Megavoltage Radiotherapy (4-20 MV): Most common method, using linear accelerators to produce high-energy X-rays. Offers advantages over Co-60: * Higher penetration * Higher dose rate * Better collimation (precise beam targeting)
D. Electron Therapy (4-20 MeV): Linear accelerators can also generate electron beams. These are suitable for superficial tumors, providing uniform treatment to a specific depth with a rapid dose fall-off beyond that depth. Depth of penetration depends on electron energy (e.g., 6 MeV ≈ 1.5 cm, 20 MeV ≈ 5.5 cm). Offers an alternative to kilovoltage X-rays for superficial tumors.
Limitations of Low-Energy X-ray Beams:
  • Unsuitable for deep-seated malignancies (thorax, abdomen, pelvis).
  • High skin dose.
  • Rapid dose fall-off with depth.
  • Higher bone dose compared to soft tissue.
II. Features of Megavoltage X-rays
  • High dose delivered at depth.
  • Maximum dose below the skin surface (skin-sparing effect).
  • Exponential dose fall-off with depth.
  • Sharp dose fall-off at beam edge (penumbra).
  • Beam shape modification via metal blocks or multileaf collimators.
  • Dose gradient creation using metal filters or wedges.
  • Treatment from any direction is possible.
  • Crossfire technique (2-4 beams) enhances target dose while sparing normal tissues.
III. EBRT Planning Process (Six Steps)
Step 1: Beam Dosimetry: Measuring the dose distribution pattern of each linear accelerator using an ionization chamber in a water tank. Calibration factors (output factors) are determined to calculate irradiation time for a specified dose.
Step 2: Planning Computer: Computer software uses measured beam data and algorithms to account for tissue density variations (often from CT scans) in dose calculations. Simpler planning can be done using tables or plots.
Step 3: Target Drawing: Defining the target volume to be irradiated. This includes: * GTV (Gross Tumor Volume): Visible tumor on imaging or clinical examination. * CTV (Clinical Target Volume): GTV plus surrounding tissue with potential microscopic tumor cells. * PTV (Planning Target Volume): CTV plus margins to account for setup uncertainties (patient positioning, organ movement, machine calibration). Critical organs (spinal cord, eyes, kidneys) are also defined.
Step 4: Dose Planning: Designing a treatment plan to uniformly irradiate the target while keeping critical organ doses within tolerance. Adjustable parameters include: * Patient position * Beam size & shape * Beam direction * Number of beams * Relative dose per beam (beam weight) * Wedging * Compensators
Step 5: Treatment Verification: Ensuring correct beam positioning and avoiding critical organ over-irradiation. Methods include: * Radiographs on a simulator. * Megavoltage radiographs or EPIDs (Electronic Portal Imaging Devices) during treatment. * In vivo dosimetry (thermoluminescence dosimeters) – the gold standard for radical treatments.
Step 6: Treatment Prescription and Delivery: The oncologist prescribes the dose, fractionation schedule, and beam configuration. This information is entered into the linear accelerator's computer system to control treatment delivery.


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Oncology- Prophylactic Cancer Surgery
I. Conditions Warranting Prophylactic Surgery:
The following conditions significantly increase cancer risk and may necessitate preventative surgery:
A. Cryptorchidism (Undescended Testis): * Procedure: Orchidopexy (surgical repositioning of the testis) or, less frequently, orchidectomy (testicular removal). * Rationale: Undescended testes are at higher risk of developing testicular cancer.
B. Familial Adenomatous Polyposis (FAP): * Procedure: Total colectomy with ileal pouch-anal anastomosis (creation of an internal pouch to replace the colon). * Rationale: FAP leads to numerous colon polyps, many of which are precancerous. Total colectomy drastically reduces colon cancer risk.
C. Ulcerative Colitis: * Procedure: Total colectomy. * Rationale: In cases of extensive ulcerative colitis (>10 years) with evidence of dysplasia (precancerous cell changes) on biopsy, total colectomy may be necessary to prevent colorectal cancer.
D. Multiple Endocrine Neoplasia (MEN) Type 2: * Procedure: Total thyroidectomy. * Rationale: MEN type 2 significantly increases the risk of medullary thyroid carcinoma. Early thyroidectomy is a preventative measure.
E. BRCA1/2 Gene Mutations: * Procedure: Prophylactic bilateral mastectomy (with optional reconstruction) and/or laparoscopic oophorectomy (ovary removal). * Rationale: BRCA1/2 mutations substantially increase the risk of breast and ovarian cancers. While prophylactic surgery is an option, the recent NICE (2013) approval of tamoxifen as a prophylactic drug for BRCA1/2 carriers might reduce the demand for surgery – this remains to be evaluated.
II. Crucial Considerations:
  • Patient Counseling: Extensive counseling is essential before recommending prophylactic surgery due to the significant physical and psychological impact. Risks and benefits must be carefully weighed.
  • Alternative Treatments: Note that in some cases, like BRCA1/2 mutations, pharmacological interventions (e.g., tamoxifen) may offer alternatives to surgery.
  • High-Risk Individuals Only: Prophylactic cancer surgery is reserved for individuals with a significantly increased risk of developing specific cancers, not for the general population.
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Oncology- Radiotherapy Fractionation

I. Core Concepts:
  • Objective of Fractionation: To determine the optimal combination of total radiation dose (Gy), number of doses (fractions), and overall treatment time to effectively target cancer while minimizing damage to healthy tissues.
  • Linear Quadratic (LQ) Model: This model describes how tissues respond to radiation. Early-reacting tissues (e.g., skin) show a linear relationship between dose and damage (α component). Late-reacting tissues (e.g., spinal cord) exhibit a quadratic relationship, meaning damage increases disproportionately with dose (β component). The LQ model supports the use of many small fractions to minimize late-reacting tissue damage.
II. Fractionation Schedules:
Two main approaches exist:
A. Few Large Daily Fractions:
  • Advantages: Fewer patient visits, less resource consumption, faster tumor response, reduced tumor repopulation during treatment.
  • Disadvantages: Limits total safe dose, increases risk of late tissue damage, reduced reoxygenation potential (which improves radiotherapy effectiveness), often insufficient to eradicate all cancer cells.
B. Many Small Daily Fractions:
  • Advantages: Less severe acute reactions (due to longer treatment time), reduced late tissue damage, allows for higher total dose, maximizes reoxygenation, potentially eradicates all cancer cells, allows dose reduction if acute reactions are unexpectedly severe.
  • Disadvantages: Increased resource and patient demand, potential for tumor repopulation during prolonged treatment, prolonged acute reactions may require supportive care.
III. Tumor and Tissue Radiosensitivity:
  • Tumor Radiosensitivity: Varies widely. Some tumors (lymphoma, seminoma) are highly radiosensitive, requiring lower doses. Others (gliomas, sarcomas) are radioresistant.
  • Normal Tissue Tolerance Doses (2Gy per fraction): These are maximum doses before significant late damage occurs:
    • Testis: 2 Gy
    • Lens of the eye: 10 Gy
    • Whole kidney: 20 Gy
    • Whole lung: 20 Gy
    • Spinal cord: 50 Gy
    • Brain: 60 Gy
  • Inter-fraction Interval: At least 6 hours should separate fractions to allow for tissue repair. With once-daily fractionation, nearly all repair occurs before the next treatment.
IV. Advanced Fractionation Techniques:
  • Hyperfractionation: Delivers many small fractions (<2gy) to increase total dose without increasing late tissue damage. may involve weekend treatments or multiple daily treatments.< />pan>
  • Accelerated Radiotherapy: Shortens overall treatment time to reduce tumor repopulation during treatment. Often combined with hyperfractionation (e.g., ChaRT regimen). Example: ChaRT (Continuous Hyperfractionated Accelerated RadioTherapy) delivers 54 Gy in 1.5 Gy fractions three times daily for 12 days.
V. Treatment Intent and Regimen Selection:
A. Radical Radiotherapy (Curative Intent):
  • Goal: Highest tolerable dose for maximal cancer eradication.
  • Lower doses used for highly radiosensitive tumors or microscopic residual disease.
  • Multiple daily fractions (~2Gy) minimize late damage.
  • Significant acute toxicity is acceptable due to potential survival benefit.
  • Requires patient fitness for daily attendance.
B. Palliative Radiotherapy (Symptom Relief):
  • Goal: Quick symptom relief, may not impact survival significantly.
  • Lowest effective dose and fraction number are preferred.
  • Avoid prolonged acute damage; late effects may be irrelevant.
  • High-dose palliative radiotherapy may be appropriate in specific advanced cases with durable local disease control as a goal and reasonable life expectancy.
VI. Key Considerations for Studying:
  • Understand the LQ model: This is fundamental to understanding why fractionation is used.
  • Compare and contrast: Clearly differentiate between few large vs. many small fractions, highlighting advantages and disadvantages of each.
  • Know tolerance doses: These are crucial for safe treatment planning.
  • Understand advanced techniques: Grasp the principles behind hyperfractionation and accelerated radiotherapy.
  • Distinguish treatment intent: Recognize how treatment goals (radical vs. palliative) influence regimen selection.




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Oncology-Surgical Oncology: Metastatic Disease - Study Guide
I. Surgery for Metastatic Disease: General Principles
  • Resection of Metastases: Resection of single (and occasionally multiple) metastatic sites is considered in carefully selected patients. Key factors include the primary tumor's location and the location of the metastases. Common sites for resection include lungs, liver, and brain. Multidisciplinary team (MDT) discussion is crucial. Prolonged survival is possible but not guaranteed.
II. Lymphatic Clearance
  • Curative Potential: In some cancers, lymphatic clearance can be curative.
  • Adjuvant Therapy Avoidance: It may eliminate the need for adjuvant chemotherapy or radiotherapy (e.g., axillary radiotherapy in breast cancer).
  • Indications: Breast, colorectal, head and neck, and penile cancers.
  • Contraindications: No role in prophylactic nodal dissection for melanoma.
  • Sentinel Node Dissection: Has a role in breast and melanoma cancers; shown to be beneficial in breast cancer (ALMANAC trial, 2004). Now a standard practice in UK and US.
III. Liver Metastases
  • Spread: Primarily hematogenous, usually via the portal venous system.
  • Detection: Often incidental findings on post-operative surveillance CT scans. Further investigations include MRI and CT-PET (to rule out extra-hepatic spread).
  • Most Experience: With colorectal cancer metastases.
  • Resection: No randomized trials support liver resection, but contemporary series show 5-year survival up to 75% in selected patients (colorectal origin) with low operative mortality (<1%) but significant morbidity (30%).< />pan>
  • Neoadjuvant Chemotherapy: Increases resectability rates and improves post-resection survival by downsizing metastases.
  • Fong Score: Predicts prognosis. Points are assigned for: tumor size >5cm; node-positive primary tumor; >1 tumor; disease-free interval <12 months; cea>200ng/mL. Higher scores indicate worse prognosis.
  • Repeated Resection: Possible (including laparoscopic approaches) with outcomes comparable to initial resection if selection criteria are met.
  • Staged Resection: Possible using portal vein embolization to encourage remnant liver hypertrophy.
  • Non-Colorectal Cancers: Benefit is variable; better outcomes reported for neuroendocrine (up to 50% 5-year survival) and genitourinary (up to 60% 5-year survival) cancers. Limited or no benefit for breast and melanoma metastases except in highly selected patients.
  • Laparoscopic Resection: Increasingly used, reducing post-operative stay and recovery time.
  • Other Treatment Options: Radiofrequency ablation (RFA), microwave ablation (newer, potential advantages over RFA), alcohol injection, and cryotherapy (less common, still used for HCC).
IV. Lung Metastases
  • Spread: Lymphatic or hematogenous.
  • Second Most Common Site: One-fifth of patients present with lung metastases as the sole site.
  • Detection: Often incidental findings on post-operative surveillance CT scans; CT-PET used to exclude extra-thoracic disease.
  • Resection Criteria: Controlled primary tumor, medically fit patient, limited lung metastases (some centers now accepting patients with lung and liver metastases from colorectal cancer for sequential resections).
  • Metastasectomy: Low morbidity and mortality; can be performed repeatedly.
  • Thoracoscopic Techniques: Commonplace.
  • 5-Year Survival: Varies significantly by primary tumor origin (e.g., osteosarcoma 40%; colorectal 35%; melanoma 20%; germ cell tumors 86%).
V. Bone Metastases
  • Presentation: Often pathological fracture.
  • Common Primary Sites: Breast, prostate, lung, thyroid, and kidney cancers.
  • Survival: Highly variable, from 3 months (lung cancer metastases) to over 4 years (breast cancer metastases).
  • Investigations: MRI and CT-PET are most accurate, followed by bone scanning.
  • Internal Fixation: Indicated for weight-bearing bones (especially lesions >2.5cm or involving circumference), painful lesions after radiotherapy, improved mobilization/nursing care, and good bone quality.
  • Spinal Metastases: Requires stabilization to prevent cord compression.
  • Treatment Options: Internal fixation (plates, intramedullary nails, prosthetic replacement); external fixation (for extensive disease); amputation (rare, for fungating tumors, recurrent infections, intractable pain); percutaneous bone cement injection (minimally invasive, for selected cases like spinal metastases).
VI. Brain Metastases
  • Common: Up to 10% of cancer patients develop brain metastases. Incidence varies by primary tumor (lung cancer highest, colorectal lowest).
  • Spread: Hematogenous; distribution reflects blood flow (cerebrum > cerebellum > brainstem).
  • Presentation: Headache, focal weakness, altered mental status, epilepsy, and hemorrhage (acute neurological state).
  • Diagnosis: MRI (detects smaller metastases than CT).
  • Survival: Without therapy: 2 months; with steroids: 3 months; with radiotherapy: 6 months.
  • Surgery: Indicated for diagnosis confirmation, pressure relief, local control improvement, and survival improvement in selected cases.
  • Poor Prognostic Indicators: Uncontrolled systemic disease, poor general health, infratentorial location, poor neurological status, short interval between primary and metastatic diagnoses.
  • Resection: Usually limited to single metastases in accessible locations; resection of multiple metastases may be considered in some cases. Prolonged survival possible (duration varies by primary tumor).
VII. Malignant Pleural Effusion
  • Surgical Intervention: Rarely indicated; usually managed medically.
  • Thoracoscopy: Occasional role for drainage, adhesion lysis, pleural biopsy, and instillation of sclerosing agents (talc or bleomycin).
  • Pleurectomy: Rarely performed (malignant mesothelioma); high morbidity and mortality (10%), only for very selected patients.
VIII. Malignant Pericardial Effusion
  • Pericardial Window: In selected patients, a pericardial window is comparable to percutaneous drainage.
  • ​
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Oncology -Radiation Oncology

I. Introduction to Radiation Oncology (Radiotherapy)

  • Definition: Treatment of malignant disease using ionizing radiation, primarily high-energy X-ray beams (External Beam Radiotherapy - EBRT).
  • Significance: Arguably the most important non-surgical cancer therapy, used in over 50% of cancer patients.

II. Historical Perspective: Key Milestones

This timeline highlights the evolution of radiotherapy techniques and understanding:

Year

Milestone

Significance

1896

Discovery of X-rays

Foundation of radiotherapy.

1898

Discovery of radium

Provided another source of ionizing radiation for treatment.

1899

Successful skin cancer treatment with X-rays

First documented successful cancer treatment using radiation.

1915

Cervical cancer treatment with radium implant

Introduction of brachytherapy (internal radiation therapy).

1922

Cure of laryngeal cancer with X-ray therapy

Demonstrated curative potential of external beam radiotherapy (EBRT).

1928

Roentgen defined as radiation exposure unit

Standardized radiation measurement.

1934

Dose fractionation principles proposed

Crucial development for optimizing treatment and minimizing side effects.

1950s

Radioactive cobalt teletherapy (1MV energy)

Advancement in technology for delivering radiation.

1960s

Megavoltage X-rays from linear accelerators

Significant improvement in radiation delivery precision and depth.

1990s

3D radiotherapy planning

Enhanced precision in targeting tumors.

2000s

IMRT, IGRT, Stereotactic radiotherapy

Advanced techniques for highly precise and targeted radiation delivery.

III. Mechanism of Action

  • Energy Absorption: X-rays passing through tissue cause ionization of molecules, producing fast-moving electrons and free radicals.
  • DNA Damage: The most crucial biological effect is DNA damage, including double-strand breaks. This damage leads to cell death, particularly in rapidly dividing cancer cells.
  • Unit of Dose: Gray (Gy) - energy absorbed per unit mass (J/kg).

IV. Fractionated Radiotherapy

  • Principle: Delivering radiation in small, daily doses (fractions) over several days or weeks.
  • Benefits:
    • Preferential sparing of normal tissue: Allows higher total doses to be safely administered.
    • Increased cancer cell kill: While minimizing damage to healthy tissue.
  • Mechanism: Allows normal tissue repair between fractions, while cancer cells, which often have impaired repair mechanisms, accumulate damage leading to their death.
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