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Diagnostic Tests – Dobutamine Stress Testing
What Is Dobutamine Stress Testing?
Dobutamine stress testing is a type of pharmacologic stress test used to evaluate myocardial perfusion and detect ischemia without requiring physical exercise. It is a noninvasive alternative to traditional treadmill testing and is particularly valuable when assessing patients who cannot achieve adequate exercise levels due to physical limitations, illness, or frailty. By stimulating the heart pharmacologically, the test reproduces the physiologic effects of exercise, allowing clinicians to identify areas of the myocardium that become ischemic under increased demand.
How Is the Test Performed?
Dobutamine, a beta-1 adrenergic agonist, is administered intravenously in gradually increasing doses. This medication increases heart rate and myocardial contractility, creating inotropic and chronotropic stress similar to exercise.
During infusion, a stress echocardiogram is performed. Clinicians watch for the development of new regional wall motion abnormalities, which indicate ischemia. Normal myocardium contracts more vigorously with dobutamine, while ischemic segments show impaired or reduced motion when stressed. This imaging pattern helps pinpoint areas of inadequate coronary blood flow.
When Should Dobutamine Stress Testing Be Used?
Dobutamine stress testing is the correct choice when a patient cannot perform adequate physical exercise and needs evaluation for ischemic heart disease. Typical scenarios include:
• A patient with a history of chest pain, but with an equivocal clinical picture
• A case where the resting EKG is nondiagnostic or uninterpretable
• Situations where pharmacologic stress is needed but Persantine (dipyridamole) cannot be used—particularly in patients with reactive airway diseases such as asthma, COPD, or emphysema
• Any patient with contraindications to vasodilator stress agents who still requires noninvasive assessment of myocardial perfusion
Its indications closely mirror those for Persantine thallium testing, but dobutamine is preferred in respiratory disease.
What Is the Most Accurate Diagnostic Test?
Although dobutamine stress testing is an effective and widely used noninvasive method for detecting myocardial ischemia, the most accurate test of myocardial perfusion remains the coronary angiogram. Angiography provides direct visualization of coronary artery anatomy and remains the gold standard for confirming obstructive coronary artery disease.
Diagnostic Tests – Dobutamine Stress Testing
What Is Dobutamine Stress Testing?
Dobutamine stress testing is a type of pharmacologic stress test used to evaluate myocardial perfusion and detect ischemia without requiring physical exercise. It is a noninvasive alternative to traditional treadmill testing and is particularly valuable when assessing patients who cannot achieve adequate exercise levels due to physical limitations, illness, or frailty. By stimulating the heart pharmacologically, the test reproduces the physiologic effects of exercise, allowing clinicians to identify areas of the myocardium that become ischemic under increased demand.
How Is the Test Performed?
Dobutamine, a beta-1 adrenergic agonist, is administered intravenously in gradually increasing doses. This medication increases heart rate and myocardial contractility, creating inotropic and chronotropic stress similar to exercise.
During infusion, a stress echocardiogram is performed. Clinicians watch for the development of new regional wall motion abnormalities, which indicate ischemia. Normal myocardium contracts more vigorously with dobutamine, while ischemic segments show impaired or reduced motion when stressed. This imaging pattern helps pinpoint areas of inadequate coronary blood flow.
When Should Dobutamine Stress Testing Be Used?
Dobutamine stress testing is the correct choice when a patient cannot perform adequate physical exercise and needs evaluation for ischemic heart disease. Typical scenarios include:
• A patient with a history of chest pain, but with an equivocal clinical picture
• A case where the resting EKG is nondiagnostic or uninterpretable
• Situations where pharmacologic stress is needed but Persantine (dipyridamole) cannot be used—particularly in patients with reactive airway diseases such as asthma, COPD, or emphysema
• Any patient with contraindications to vasodilator stress agents who still requires noninvasive assessment of myocardial perfusion
Its indications closely mirror those for Persantine thallium testing, but dobutamine is preferred in respiratory disease.
What Is the Most Accurate Diagnostic Test?
Although dobutamine stress testing is an effective and widely used noninvasive method for detecting myocardial ischemia, the most accurate test of myocardial perfusion remains the coronary angiogram. Angiography provides direct visualization of coronary artery anatomy and remains the gold standard for confirming obstructive coronary artery disease.
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Diagnostic Tests – Sestamibi Testing
What Is Sestamibi Testing?
Sestamibi testing—often referred to by its tracer name Tc-99m sestamibi—is a form of nuclear stress testing used to evaluate myocardial perfusion. It involves injecting a radiopharmaceutical (technetium-99m) that accumulates in healthy, well-perfused myocardial tissue. Because the tracer depends on both blood flow and viable cardiac cells, areas of ischemia or infarction appear as perfusion defects on imaging. Like other nuclear stress tests, it helps determine whether chest pain or abnormal EKG findings are due to underlying coronary artery disease.
How Is the Test Performed?
During the procedure, Tc-99m–labeled compounds are injected into the bloodstream during both stress and rest phases. A gamma camera then captures images of tracer uptake in the myocardium.
Healthy tissue receives adequate blood flow and shows normal tracer uptake, whereas diseased, ischemic, or infarcted myocardium demonstrates reduced uptake. The pattern of defect behavior is key:
- Reversible defect: reduced uptake during stress but improved at rest → ischemia (viable myocardium that becomes underperfused during stress).
- Fixed defect: reduced uptake on both stress and rest images → infarcted or scarred myocardium.
This allows clinicians to distinguish between viable, at-risk myocardium and areas of permanent damage.
When Should You Choose Sestamibi Testing?
The most practical “Kaplan-style” indication is that Tc-99m sestamibi is the preferred nuclear stress test in certain patient populations where standard imaging methods are limited by technical barriers. It is particularly useful in:
- Obese patients, where ultrasound penetration for stress echocardiography is poor
- Female patients with large breasts, where breast tissue can interfere with echo imaging or make exercise EKG less reliable
Because sestamibi imaging provides clearer results in these scenarios, it is often selected when other stress modalities may produce nondiagnostic images or false results.
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Diagnostic Tests – Thallium Stress Testing
What Is Thallium Stress Testing?
Thallium stress testing is a nuclear imaging method used to evaluate myocardial perfusion and detect areas of ischemia. It is considered the most accurate noninvasive technique for assessing blood flow to the heart muscle without performing coronary angiography. During this test, a radioactive tracer—thallium-201—is injected into the bloodstream. Because thallium behaves similarly to potassium, healthy myocardial cells take it up readily. Areas with reduced blood flow, however, demonstrate decreased tracer uptake, allowing clinicians to visualize perfusion deficits both at rest and under stress conditions.
When Is Thallium Stress Testing the Correct Answer?
Thallium stress testing is often chosen as an alternative to stress echocardiography, especially when evaluation of ischemia requires imaging that does not rely on ultrasound. It is particularly indicated when resting EKG abnormalities make standard exercise EKG interpretation unreliable, such as in patients with:
In these cases, EKG changes alone cannot reliably detect ischemia, so thallium imaging provides crucial additional information.
Thallium scanning is also used to:
What Is the Most Accurate Test?
Although thallium stress testing is the most accurate noninvasive method of assessing myocardial perfusion, the gold standard—and most accurate overall diagnostic test—is coronary angiography. Angiography allows direct visualization of the coronary arteries and provides precise information about the presence, location, and severity of stenosis.
What Is Thallium Stress Testing?
Thallium stress testing is a nuclear imaging method used to evaluate myocardial perfusion and detect areas of ischemia. It is considered the most accurate noninvasive technique for assessing blood flow to the heart muscle without performing coronary angiography. During this test, a radioactive tracer—thallium-201—is injected into the bloodstream. Because thallium behaves similarly to potassium, healthy myocardial cells take it up readily. Areas with reduced blood flow, however, demonstrate decreased tracer uptake, allowing clinicians to visualize perfusion deficits both at rest and under stress conditions.
When Is Thallium Stress Testing the Correct Answer?
Thallium stress testing is often chosen as an alternative to stress echocardiography, especially when evaluation of ischemia requires imaging that does not rely on ultrasound. It is particularly indicated when resting EKG abnormalities make standard exercise EKG interpretation unreliable, such as in patients with:
- Left bundle branch block (LBBB)
- Baseline ST-segment abnormalities
- Left ventricular hypertrophy with strain pattern
- A ventricular pacemaker
- Digoxin effects on the EKG
In these cases, EKG changes alone cannot reliably detect ischemia, so thallium imaging provides crucial additional information.
Thallium scanning is also used to:
- Localize the specific region of ischemia within the myocardium
- Assess the success of revascularization after coronary artery bypass grafting (CABG) or angioplasty
- Provide a perfusion map that helps guide further testing or management
What Is the Most Accurate Test?
Although thallium stress testing is the most accurate noninvasive method of assessing myocardial perfusion, the gold standard—and most accurate overall diagnostic test—is coronary angiography. Angiography allows direct visualization of the coronary arteries and provides precise information about the presence, location, and severity of stenosis.
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Oncology- Drug Resistance in Oncology
This study guide summarizes the provided text on drug resistance in cancer treatment. Understanding these mechanisms is crucial for developing effective therapies.
I. Introduction: The Problem of Drug Resistance
This section details the various ways cancer cells evade chemotherapy. Note that multiple mechanisms can operate simultaneously in a single patient.
A. Pharmacological Resistance: The effective drug concentration at the target site is insufficient due to:
Clinical drug resistance is a complex, multifactorial problem. The relative contribution of each mechanism varies greatly between patients. Further research into cell cycle regulation, cell life, and cell death is essential to overcome this major obstacle in cancer treatment. Understanding these diverse mechanisms is vital for developing strategies to circumvent drug resistance and improve cancer therapy outcomes.
This study guide summarizes the provided text on drug resistance in cancer treatment. Understanding these mechanisms is crucial for developing effective therapies.
I. Introduction: The Problem of Drug Resistance
- Laboratory vs. Clinical Resistance: Much research uses artificially induced resistance in cell lines (often >40-100 fold increase in drug concentration needed to overcome resistance). The relevance of this to clinical resistance remains unclear.
This section details the various ways cancer cells evade chemotherapy. Note that multiple mechanisms can operate simultaneously in a single patient.
A. Pharmacological Resistance: The effective drug concentration at the target site is insufficient due to:
- Organ Toxicity: Limiting dosage due to side effects in other organs.
- Enhanced Drug Clearance: The body removes the drug too quickly.
- Physical Barriers: Tumour avascularity (lack of blood vessels) prevents drug delivery.
- De Novo Resistance: The tumour is unresponsive to chemotherapy from the start.
- Acquired Resistance: Initial response followed by tumour regrowth and resistance.
- Combination of De Novo and Acquired: Both mechanisms are at play.
- Reduced Drug Uptake: Mutations prevent drug entry into the cell.
- Increased Detoxification: Faster metabolism and elimination of the drug.
- Target Site Mutation: The drug's target is altered, making it ineffective.
- Enhanced DNA Repair: Increased efficiency in repairing drug-induced damage.
- P-170 Glycoprotein (Pgp): Overexpression of this 170kDa glycoprotein creates an energy-dependent drug efflux pump. Drugs enter the cell but are actively pumped back out, reducing intracellular concentration. This is common with anthracyclines, taxanes, and etoposide; resistance to one often implies resistance to others (multidrug resistance).
- 190kDa Efflux Pump: Another energy-dependent pump causing drug efflux or sequestration within organelles. Substrate specificity similar to Pgp but generally associated with less taxane resistance. Clinical significance less established than Pgp.
- Thiol-Based Detoxification: This cellular thiol participates in detoxification pathways, particularly against alkylating agents (e.g., cisplatin) and free radicals (e.g., doxorubicin). Overexpression leads to resistance; glutathione depletion strategies have yielded mixed clinical results.
- Apoptosis Failure: Many cytotoxic drugs induce apoptosis (programmed cell death). Failure to activate apoptosis, often linked to p53 dysfunction ("guardian of the genome"), allows damaged cells to survive and proliferate, leading to resistance. Gene therapy targeting this mechanism is under investigation.
Clinical drug resistance is a complex, multifactorial problem. The relative contribution of each mechanism varies greatly between patients. Further research into cell cycle regulation, cell life, and cell death is essential to overcome this major obstacle in cancer treatment. Understanding these diverse mechanisms is vital for developing strategies to circumvent drug resistance and improve cancer therapy outcomes.
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Oncology- Chemotherapeutic Dose Intensification in Oncology
This guide summarizes the provided text on dose intensification in cancer treatment, focusing on key concepts and clinical applications.
I. Dose-Response and Dose Intensification:
HDC has shown efficacy in various cancers, although the success rates vary:
This guide summarizes the provided text on dose intensification in cancer treatment, focusing on key concepts and clinical applications.
I. Dose-Response and Dose Intensification:
- Central Idea: Cancer cell drug resistance is often relative, not absolute. Therefore, arbitrarily reducing drug doses should be avoided.
- Clinical Implications: To overcome resistance and achieve better outcomes, dose intensification strategies are employed. This might necessitate using supportive care (e.g., prophylactic antibiotics, hematopoietic growth factors) to mitigate the increased toxicity associated with higher doses. The goal is to deliver potentially curative chemotherapy on a timely basis, even if it means managing side effects.
- Limitations of Conventional Dose Escalation: Increasing chemotherapy doses within a conventional range has inconsistently improved response rates and minimally impacted survival, often with increased toxicity.
- Hematopoietic Support: Advances in hematopoietic support (using autologous bone marrow or cytokine-mobilized peripheral blood progenitors – PBPs) have enabled the use of HDC. These methods rescue the bone marrow from the myelosuppressive effects of the high-dose chemotherapy.
- PBP Autografting: Superior to marrow autografting, leading to shorter periods of neutropenia and thrombocytopenia, reduced mortality, and reduced morbidity. This involves harvesting PBPs from the peripheral blood via leucopheresis, then re-infusing them after HDC.
- Timing and Administration of HDC: Primarily used as consolidation therapy after conventional chemotherapy. Less commonly used as first-line (initial) treatment. Can be given in single or multiple cycles.
HDC has shown efficacy in various cancers, although the success rates vary:
- Relapsed aggressive lymphoma: Proven salvage therapy (treatment after other therapies have failed).
- Refractory lymphoma: Lower remission rates (around 10%).
- Poor prognosis Non-Hodgkin lymphoma (NHL): May be used as a first-line treatment.
- Multiple myeloma: May be used as a first-line treatment.
- Relapsed/refractory Hodgkin's disease: May be used as a first-line treatment.
- Acute leukemia: Especially relevant when a bone marrow donor is unavailable.
- Metastatic testicular germ cell tumors: In cases of relapse after the second remission.
- Alternative to HDC: This strategy shortens the interval between cycles of conventional chemotherapy, typically supported by granulocyte colony-stimulating factor (G-CSF).
- Status: Shows promise (particularly in adjuvant therapy for high-risk breast cancer), but remains experimental.
- Myelosuppression: Suppression of bone marrow function, leading to reduced blood cell production (neutropenia, thrombocytopenia).
- Autografting: Transplantation of the patient's own bone marrow or PBPs.
- Leucopheresis: Procedure to separate white blood cells (including PBPs) from blood.
- Neutropenia: Low neutrophil count (type of white blood cell).
- Thrombocytopenia: Low platelet count.
- Adjuvant chemotherapy: Chemotherapy given after the primary treatment (surgery, radiation) to reduce the risk of recurrence.
- Consolidation chemotherapy: Intensive chemotherapy given after achieving remission to further reduce the risk of recurrence.
- Salvage therapy: Treatment given after initial treatment has failed.
- Refractory: Resistant to treatment.
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Oncology- The Role of Unsealed Radionuclides in Oncology
I. Nuclear Medicine in Oncology: The Big Picture
Nuclear medicine uses radioactive substances (radionuclides) to:
A. Bone Scintigraphy:
I. Nuclear Medicine in Oncology: The Big Picture
Nuclear medicine uses radioactive substances (radionuclides) to:
- Localize tumors: Pinpoint the location of a cancerous growth.
- Detect metastases: Identify cancer that has spread to other parts of the body.
- Monitor treatment response & detect recurrence: Track how well treatment is working and identify any cancer that comes back.
- Deliver targeted radiotherapy: Deliver radiation directly to cancerous cells.
- Radiopharmaceuticals: These are the workhorses. They consist of a radionuclide (the radioactive part) attached to a ligand (a molecule that targets specific cells or tissues). Gamma rays emitted by the radionuclide are detected to create images.
- Tumour detection mechanism: Radiopharmaceuticals concentrate in areas of abnormal biological activity, such as tumors, allowing visualization of these areas that are undetectable via cross-sectional imaging like CT or MRI.
- Scintigraphy limitations: While scintigraphy offers functional information that CT and MRI lack, it provides less anatomical detail. Often, multiple imaging modalities are used together.
- Common Radiopharmaceuticals:
- Iodine-123 (-131): Used for thyroid imaging and therapy.
- Thallium-201 (201Tl) & Gallium-67 (67Ga): Used for various imaging purposes.
- Technetium-99m (99mTc): An ideal radionuclide for imaging due to many favorable characteristics (details below).
- Gamma Cameras: Traditionally used for planar (2D) and whole-body scintigraphy.
- Single-Photon Emission Computed Tomography (SPECT): Uses computer processing to generate cross-sectional (3D) images, offering improved sensitivity and localization compared to planar scintigraphy.
- Positron Emission Tomography (PET): Uses positron-emitting radionuclides and provides quantitative tomographic images. Commonly used with 18F-fluorodeoxyglucose (FDG) to measure glucose metabolism in tumors, providing information about tumor vitality, cell turnover, and response to therapy.
A. Bone Scintigraphy:
- Radiopharmaceuticals: 99mTc-methylene diphosphonate (MDP) or 99mTc-hydroxymethylene diphosphonate (HDP).
- Procedure: Injected 2-4 hours before imaging.
- Sensitivity: High sensitivity (80-100%) for many cancers (breast, prostate, lung, etc.). Lower sensitivity (around 75%) for others (melanoma, small-cell lung cancer, etc.). "Cold" defects may indicate lesions lacking osteoblastic activity.
- Radiopharmaceuticals: 131I, 123I, and 99mTc (pertechnetate).
- 131I advantages & disadvantages: Cheap and readily available, but has a long half-life and emits alpha particles, leading to significant radiation exposure.
- 123I advantages & disadvantages: Excellent imaging properties and shorter half-life but expensive.
- 99mTc: Trapped in the thyroid temporarily but not permanently incorporated.
- Clinical indications: Evaluation of nodules and post-surgery follow-up for differentiated thyroid cancer.
- Principles: Uses tumor-seeking radiopharmaceuticals. Ideal agents have high tumor-to-background ratios, long retention times in tumors, and emit radiation energetic enough for therapy but with limited penetration to minimize damage to healthy tissues.
- Clinically useful radiopharmaceuticals: 131I, 89Sr, 32P, 186Re, 153Sm, 90Y.
- Uses: Treatment of thyrotoxicosis and differentiated thyroid carcinoma (ablation of remaining thyroid tissue after surgery, treatment of recurrent or metastatic disease).
- Uses: Treatment of neural crest tumors (pheochromocytoma, neuroblastoma, paraganglioma, medullary thyroid carcinoma). Variable success rates (e.g., >50% for malignant pheochromocytoma).
- Mechanism: Mimic calcium or phosphate to accumulate in areas of high bone turnover (near metastases).
- Examples: 89Sr (calcium analogue), 32P, 186Re, HEDP, and 153Sm (phosphate analogues).
- 89Sr: First systemic treatment for bone metastases in prostate cancer. Provides pain relief and delays disease progression in 75-80% of patients for 1-6 months. Myelosuppression (bone marrow suppression) is a side effect.
- 32P: Historically used for bone pain relief but limited by bone marrow toxicity.
- Mechanism: Direct injection of radiopharmaceuticals into body cavities (pleural, pericardial, peritoneal, bladder, CSF, cysts) to target tumors locally, minimizing systemic exposure.
- Radiopharmaceuticals: Colloids and monoclonal antibodies labeled with 32P, 90Y, or 131I.
- Concept: Targeted delivery of radiation using antibodies specific to tumor cells.
- Current status: Despite initial promise, radioimmunotherapy has faced numerous challenges and its future remains uncertain.
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Oncology-Total Body Irradiation (TBI)
I. What is TBI?
Total body irradiation (TBI) is a high-dose radiation therapy used to eliminate residual malignant disease and ablate bone marrow before stem cell transplantation. This is often combined with high-dose chemotherapy. The goal is to improve cure rates for sensitive tumors.
II. Aims of TBI:
Crucial before TBI to assess patient suitability and mitigate risks:
A. Acute Effects (occurring shortly after treatment):
I. What is TBI?
Total body irradiation (TBI) is a high-dose radiation therapy used to eliminate residual malignant disease and ablate bone marrow before stem cell transplantation. This is often combined with high-dose chemotherapy. The goal is to improve cure rates for sensitive tumors.
II. Aims of TBI:
- Eliminate residual cancer: Destroy any remaining cancer cells.
- Ablate bone marrow: Completely destroy the patient's existing bone marrow to allow successful engraftment (establishment) of donor stem cells.
- Immune suppression: Reduce the immune system's response, especially crucial for non-haplotype identical grafts (where the donor's and recipient's HLA genes aren't completely matched).
- Hematological malignancies: Relapsed acute leukemia, high-grade non-Hodgkin lymphoma (NHL), and myeloma often precede bone marrow or stem cell transplants that use TBI.
- Other malignancies: Neuroblastoma is an example.
- Autologous: The patient receives their own stem cells (peripheral or cryopreserved marrow) harvested before high-dose therapy.
- Allogeneic: The patient receives stem cells from a matched or mismatched donor (often a family member or from a donor registry). Mismatched grafts may be one haplotype identical.
Crucial before TBI to assess patient suitability and mitigate risks:
- Disease remission: The cancer must be in remission (dormant) before proceeding.
- Organ function: Adequate renal (kidney), cardiac (heart), hepatic (liver), and pulmonary (lung) function is essential to handle treatment toxicity.
- Medication assessment: Review medication history for potential interactions or side effects that could exacerbate TBI's effects, including:
- Neurotoxicity: Asparaginase
- Renal toxicity: Platinum, Ifosfamide
- Pulmonary toxicity: Methotrexate (MTX), Bleomycin
- Cardiac toxicity: Cyclophosphamide, Anthracyclines
- Sanctuary sites: Assess the need for additional treatment to areas where cancer cells may hide (sanctuary sites), such as the central nervous system (CNS), testes, and mediastinum.
- Antiemetics: Administer intravenously (IV) to prevent nausea and vomiting. Commonly includes a 5-HT antagonist and dexamethasone.
- Sedation: May require additional sedation with phenobarbital or diazepam. Ketamine anesthesia may be necessary for very young children.
- Linear accelerator: A linear accelerator is used, optimally with 6MV energy.
- Fractionated TBI: Preferred for convenience, delivering radiation in smaller doses over several days.
- Patient positioning: Patient lies on a couch behind a Perspex sheet (for consistent skin dose), alternating between side and back positions. Opposed fields are used for half the treatment time.
- Distance: The couch is positioned at an extended distance to achieve the necessary body coverage.
- Dose inhomogeneity: Dose distribution isn't uniform due to body shape and tissue density differences (e.g., lungs). Bolus or lung shielding may compensate, but often isn't necessary with the described schedules.
- Dose-limiting organ: The lungs are the most vulnerable organ to radiation damage.
- Dosimetry: Paired lithium fluoride dose meters or diodes measure the dose distribution throughout the body. Readings are taken from defined sites (lung, mediastinum, abdomen, pelvis).
- Midline dose: Averaging anterior-posterior (AP) and posterior-anterior (PA) readings.
- CT scanning: Whole-body CT scans with planning software can also determine doses.
- Adults: Optimal fractionated doses are 13.2-14.4 Gy (depending on the prescription point). The maximum lung dose (dose-limiting) shouldn't exceed 14.4 Gy.
- Children: May tolerate slightly higher doses than adults. The MRC protocol uses eight 1.8 Gy fractions over four days. Many other schedules exist.
A. Acute Effects (occurring shortly after treatment):
- Nausea and vomiting: Start about 6 hours after the first fraction.
- Parotid swelling: Occurs in the first 24 hours, resolving spontaneously.
- Hypotension: Low blood pressure.
- Fever: Usually controlled with steroids.
- Diarrhoea: Occurs around day 5 due to gastrointestinal (GI) mucositis (inflammation of the mucous membranes).
- Pneumonitis: Lung inflammation causing shortness of breath and characteristic X-ray changes.
- Somnolence: Sleepiness, anorexia (loss of appetite), and sometimes nausea (6-8 weeks post-treatment), resolves within 7-10 days.
- Cataracts: Develop in <20% of patients, increasing in incidence for 2-6 years.< />pan>
- Hormonal changes: Azoospermia (sterility in males) and amenorrhea (absence of menstruation) are common; occasional cases of maintained fertility exist.
- Hypothyroidism: Thyroid damage, sometimes combined with pituitary damage.
- Growth impairment (children): Impaired growth hormone production and early epiphyseal fusion (bone growth plate closure) lead to stunted growth.
- Second malignancies: A 5-fold increased risk of developing new cancers, including brain tumors, oral and rectal carcinomas, and lymphoid system malignancies (due to prolonged immune suppression).
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