Chapter 33 — Anti-Cancer Drugs Part I: Pharmacology — Module 4 — Topoisomerase Inhibitors and Antitumor Antibiotics
1. [CASE 1 — QUESTION 1]
A 59-year-old woman, M.R., with newly diagnosed metastatic colorectal cancer is being prepared for first-line FOLFIRI (folinic acid, fluorouracil, irinotecan). She has no significant comorbidities. As part of pre-treatment planning, pharmacogenomic testing is sent and returns a UGT1A1*28/*28 genotype (homozygous for the reduced-activity promoter variant of the enzyme that inactivates SN-38, the active metabolite of irinotecan, by glucuronidation). The oncology team must decide how this result affects the irinotecan dosing for cycle 1. Which action is most appropriate?
A) Proceed at the standard irinotecan dose, since genotype does not affect systemic toxicity
B) Consider a reduced irinotecan starting dose, because impaired glucuronidation lets SN-38 accumulate and prolongs its exposure, increasing the risk of severe neutropenia and diarrhea
C) Increase the irinotecan dose, since the variant accelerates SN-38 clearance
D) Replace irinotecan with topotecan, since UGT1A1 genotype predicts topotecan toxicity identically
E) Omit folinic acid to offset the genetic toxicity risk
ANSWER: B
Rationale:
Homozygous UGT1A1*28 markedly lowers the glucuronidation capacity that inactivates SN-38, so the active metabolite accumulates to higher and more prolonged concentrations, raising the risk of severe neutropenia and grade 3 to 4 diarrhea; the appropriate response is to consider a reduced irinotecan starting dose with close monitoring.
Option A: Option A is incorrect because the variant directly affects systemic SN-38 exposure and therefore marrow and gut toxicity.
Option C: Option C is incorrect because the variant reduces, not accelerates, SN-38 clearance, so increasing the dose would compound toxicity.
Option D: Option D is incorrect because topotecan toxicity is not governed by UGT1A1 (it is renally cleared and not a UGT1A1-dependent prodrug), so the genotype does not transfer to topotecan dosing.
Option E: Option E is incorrect because folinic acid modulates fluorouracil activity and does not offset irinotecan-related genetic toxicity risk.
2. [CASE 1 — QUESTION 2]
Continuing with the same patient. M.R. begins her first irinotecan infusion at a reduced dose. About 20 minutes into the infusion she develops crampy abdominal pain, profuse sweating, watery eyes, a runny nose, and the sudden onset of watery diarrhea. Her vital signs are stable. What is the most appropriate immediate intervention?
A) High-dose loperamide started at the first loose stool
B) Permanent discontinuation of irinotecan as a drug allergy
C) Empiric oral vancomycin for Clostridioides difficile colitis
D) Atropine, because this is the early cholinergic syndrome from irinotecan-mediated acetylcholinesterase inhibition
E) A stimulant laxative to clear the offending metabolite
ANSWER: D
Rationale:
The timing during the infusion and the cholinergic features (cramping, diaphoresis, lacrimation, rhinorrhea, early diarrhea) identify the early cholinergic syndrome caused by irinotecan inhibition of acetylcholinesterase; the correct immediate treatment is atropine, with prophylactic atropine considered for later cycles.
Option A: Option A is incorrect because loperamide treats the late mucosal-injury diarrhea, not the early cholinergic syndrome.
Option B: Option B is incorrect because this is a predictable, treatable pharmacologic effect rather than an allergy mandating permanent discontinuation.
Option C: Option C is incorrect because the picture is a drug-induced cholinergic effect, not an infection, so vancomycin is inappropriate.
Option E: Option E is incorrect because a stimulant laxative would worsen the diarrhea and does not address the cholinergic mechanism that atropine targets.
3. [CASE 1 — QUESTION 3]
Continuing with the same patient. Five days after the infusion, M.R. telephones reporting more than ten watery stools per day for the past 24 hours despite taking loperamide at home. She also reports a temperature of 38.7 degrees Celsius and lightheadedness. A same-day laboratory check shows an absolute neutrophil count of 500 per microliter. What is the most appropriate management?
A) Admit for intravenous fluid resuscitation and empiric broad-spectrum antibiotics, because severe late diarrhea combined with febrile neutropenia is potentially life-threatening
B) Continue home loperamide and oral fluids with reassurance
C) Administer atropine, since this delayed diarrhea is cholinergic
D) Stop loperamide and give a stimulant laxative to clear residual SN-38
E) Defer evaluation and schedule a routine outpatient colonoscopy in two weeks
ANSWER: A
Rationale:
Severe late irinotecan diarrhea with fever and neutropenia is an emergency: volume depletion plus a damaged mucosal barrier and low neutrophil count create a high risk of bacterial translocation and sepsis, so the patient requires hospital admission for intravenous hydration and empiric broad-spectrum antibiotics.
Option B: Option B is incorrect because home management is inadequate and dangerous once febrile neutropenia and volume depletion are present.
Option C: Option C is incorrect because late diarrhea is mucosal (SN-38), not cholinergic, so atropine is not the treatment.
Option D: Option D is incorrect because a stimulant laxative would worsen fluid losses and is contraindicated.
Option E: Option E is incorrect because deferring care ignores the acute, potentially fatal combination of febrile neutropenia and severe diarrhea that demands immediate inpatient treatment.
4. [CASE 1 — QUESTION 4]
Continuing with the same patient. After M.R. recovers, a trainee asks why irinotecan causes late diarrhea specifically, given that the liver had already inactivated much of the SN-38 by glucuronidation. What is the correct mechanistic explanation for the late diarrhea?
A) The liver fails to glucuronidate SN-38 at all, so active drug is excreted unchanged into the gut
B) Late diarrhea is caused by direct acetylcholinesterase inhibition in the colon
C) Intestinal bacterial beta-glucuronidase deconjugates the inactive SN-38 glucuronide (SN-38G) in the gut lumen back to active SN-38, which directly injures the intestinal mucosa
D) Late diarrhea results from osmotic load created by the infusion vehicle
E) Late diarrhea is an autoimmune colitis triggered by irinotecan metabolites
ANSWER: C
Rationale:
After hepatic glucuronidation inactivates SN-38 to SN-38G and it is excreted in bile, intestinal bacterial beta-glucuronidase cleaves SN-38G back to active SN-38 within the gut lumen, where it directly damages the mucosa and drives the late diarrhea; this enterohepatic regeneration is the key mechanism.
Option A: Option A is incorrect because the liver does glucuronidate SN-38 (the issue is gut reactivation of the conjugate, not a complete failure to conjugate).
Option B: Option B is incorrect because acetylcholinesterase inhibition explains the early cholinergic diarrhea, not the late mucosal diarrhea.
Option D: Option D is incorrect because the late diarrhea is a direct cytotoxic mucosal injury, not an osmotic effect of the vehicle.
Option E: Option E is incorrect because the late diarrhea is direct SN-38 mucosal toxicity, not an autoimmune colitis.
5. [CASE 2 — QUESTION 1]
A 37-year-old man, T.K., has good-risk metastatic testicular germ cell tumor and is being planned for curative-intent chemotherapy. He has a history of moderate emphysema, and his pretreatment pulmonary function testing shows a reduced diffusing capacity for carbon monoxide (DLCO). The default regimen is three cycles of BEP (bleomycin, etoposide, cisplatin). Considering his pulmonary risk, which regimen modification best preserves curative intent while minimizing avoidable toxicity?
A) Proceed with BEP unchanged, since pulmonary risk does not affect germ cell tumor regimen choice
B) Replace cisplatin with carboplatin to reduce lung injury
C) Double the bleomycin dose to shorten the total number of cycles
D) Add prophylactic dexrazoxane to protect the lungs from bleomycin
E) Substitute four cycles of EP (etoposide, cisplatin), omitting bleomycin to avoid added pulmonary toxicity while maintaining comparable cure rates in good-risk disease
ANSWER: E
Rationale:
A reduced DLCO with underlying emphysema marks T.K. as high risk for bleomycin pulmonary toxicity, so the rational modification is to omit bleomycin and give four cycles of EP, which achieves comparable cure rates to three cycles of BEP in good-risk germ cell tumor while removing the bleomycin lung hazard.
Option A: Option A is incorrect because pulmonary risk factors do influence whether bleomycin should be included; ignoring a reduced DLCO would expose him to avoidable injury.
Option B: Option B is incorrect because substituting carboplatin addresses platinum toxicities, not bleomycin lung toxicity, and can compromise cure in germ cell tumor.
Option C: Option C is incorrect because increasing the bleomycin dose would raise, not lower, pulmonary toxicity risk.
Option D: Option D is incorrect because dexrazoxane protects against anthracycline cardiotoxicity and has no established role against bleomycin pulmonary toxicity.
6. [CASE 2 — QUESTION 2]
Continuing with the same patient. T.K.'s individual pulmonary risk is reconsidered and a bleomycin-containing plan is ultimately undertaken with careful monitoring. Over two cycles his serum creatinine rises and his creatinine clearance falls, attributed to cisplatin nephrotoxicity. Beyond adjusting cisplatin, why does the worsening renal function specifically heighten concern about bleomycin?
A) Bleomycin is hepatically cleared, so renal function does not affect its levels
B) Bleomycin is eliminated renally, so declining renal function reduces its clearance, increases drug exposure, and raises the risk of bleomycin pulmonary toxicity, warranting dose and monitoring reassessment
C) Renal impairment converts bleomycin into a cardiotoxic metabolite
D) Bleomycin requires renal activation, so worse renal function renders it ineffective
E) Renal function affects only etoposide and has no bearing on bleomycin
ANSWER: B
Rationale:
Bleomycin is eliminated predominantly by the kidneys, so a decline in renal function reduces its clearance, increases systemic exposure, and thereby raises the risk of its dose-limiting pulmonary toxicity; worsening renal function should prompt reassessment of bleomycin dosing and intensified pulmonary monitoring.
Option A: Option A is incorrect because bleomycin is renally, not hepatically, cleared.
Option C: Option C is incorrect because renal impairment does not transform bleomycin into a cardiotoxic metabolite; the concern is accumulation and lung toxicity.
Option D: Option D is incorrect because bleomycin does not require renal activation; impaired renal function increases exposure rather than abolishing efficacy.
Option E: Option E is incorrect because, although etoposide also needs renal dose consideration, renal function very much affects bleomycin clearance and pulmonary risk.
7. [CASE 2 — QUESTION 3]
Continuing with the same patient. Midway through therapy, T.K. reports a new dry cough and dyspnea on exertion. Serial testing shows his DLCO has fallen substantially from baseline, and a high-resolution chest CT shows bilateral basal ground-glass opacities. What does this most likely represent, and what is the appropriate response?
A) Cisplatin nephrotoxicity; intensify intravenous hydration
B) Etoposide-related secondary leukemia; obtain a bone marrow biopsy
C) An expected benign change; continue therapy unchanged
D) Early bleomycin pulmonary toxicity; consider discontinuing bleomycin and pursue pulmonary evaluation, since DLCO decline precedes overt symptoms
E) Doxorubicin cardiomyopathy; obtain echocardiography and start dexrazoxane
ANSWER: D
Rationale:
A falling DLCO with a new nonproductive cough, exertional dyspnea, and basal ground-glass opacities in a patient receiving bleomycin is the classic early picture of bleomycin pulmonary toxicity; because DLCO decline precedes overt symptoms, this should prompt consideration of stopping bleomycin and pursuing pulmonary evaluation.
Option A: Option A is incorrect because the findings are pulmonary and DLCO-based, not renal.
Option B: Option B is incorrect because the picture is interstitial lung injury, not leukemia, and a marrow biopsy does not address declining DLCO.
Option C: Option C is incorrect because a substantial symptomatic DLCO decline with imaging changes is not benign and demands action.
Option E: Option E is incorrect because doxorubicin is not part of standard BEP and causes cardiomyopathy detected by echocardiography, not the DLCO and ground-glass changes described, which point to bleomycin lung toxicity.
8. [CASE 2 — QUESTION 4]
Continuing with the same patient. Several months after completing his bleomycin-containing therapy, T.K. requires an emergency appendectomy under general anesthesia. The anesthesia team asks how his prior bleomycin exposure should affect intraoperative management. What is the most appropriate guidance?
A) Keep the inspired oxygen fraction as low as is consistent with adequate oxygen saturation during and after anesthesia, because bleomycin-sensitized lung can develop severe injury with high oxygen exposure and there is no firmly established safe interval after bleomycin
B) Use standard high inspired oxygen, since the pulmonary risk reliably expires within a few months
C) Halve all neuromuscular blocker doses, because bleomycin prolongs paralysis; oxygen settings need no adjustment
D) Avoid all volatile anesthetic agents because they react chemically with residual bleomycin
E) Pretreat with high-dose corticosteroids, which fully eliminate the oxygen-related pulmonary risk
ANSWER: A
Rationale:
The bleomycin-oxygen interaction means high inspired oxygen can trigger severe, potentially fatal lung injury in previously exposed patients, with no firmly established safe interval after which the risk disappears; the correct management is to titrate the inspired oxygen fraction to the lowest level consistent with adequate saturation during and after anesthesia and to alert the anesthesia team.
Option B: Option B is incorrect because the risk does not reliably expire in a few months, so high oxygen is not safe.
Option C: Option C is incorrect because bleomycin does not prolong neuromuscular blockade, and oxygen fraction is precisely what must be restricted.
Option D: Option D is incorrect because the hazard is high inspired oxygen, not a reaction with volatile anesthetics.
Option E: Option E is incorrect because corticosteroids do not eliminate the oxygen-related pulmonary risk; oxygen titration remains essential.
9. [CASE 3 — QUESTION 1]
A 54-year-old woman, L.D., received a substantial cumulative dose of epirubicin during adjuvant therapy for breast cancer four years ago. She now presents with a HER2-positive recurrence (overexpressing the human epidermal growth factor receptor 2) for which an anthracycline-containing regimen plus trastuzumab is being considered. Before prescribing, the oncologist wants to estimate how much of her safe lifetime anthracycline exposure remains. What is the correct approach?
A) Count only the planned new anthracycline dose, since the prior epirubicin has cleared the body
B) Disregard the prior epirubicin because it was a different anthracycline for a different cancer
C) Convert the prior epirubicin and the planned anthracycline into common doxorubicin-equivalent units and sum them, because anthracycline cardiotoxicity is cumulative and irreversible across all lifetime exposure regardless of which anthracycline was used
D) Add the raw milligrams of each drug together without any conversion factor
E) Assume cardiac tolerance resets with the new diagnosis, so prior exposure no longer counts
ANSWER: C
Rationale:
Because anthracycline cardiotoxicity reflects cumulative, irreversible cardiomyocyte injury that accrues across all anthracycline exposure, the correct method is to express prior epirubicin and the planned anthracycline in common doxorubicin-equivalent units (epirubicin is less cardiotoxic per milligram, so a conversion factor applies) and sum them to gauge the remaining safe margin.
Option A: Option A is incorrect because plasma clearance does not erase accumulated cardiac injury; prior exposure still counts.
Option B: Option B is incorrect because both drugs are anthracyclines with shared cardiotoxic mechanisms, so prior exposure is directly relevant.
Option D: Option D is incorrect because raw milligram addition ignores the differing per-milligram cardiotoxicity; conversion to equivalents is required.
Option E: Option E is incorrect because cardiac risk does not reset with a new diagnosis; the cumulative principle persists across the patient's lifetime.
10. [CASE 3 — QUESTION 2]
Continuing with the same patient. The team plans to use both an anthracycline and trastuzumab (an anti-HER2 monoclonal antibody) for L.D. They decide to give the anthracycline first and trastuzumab afterward rather than concurrently. What is the pharmacological basis for this sequencing decision?
A) Trastuzumab chemically degrades the anthracycline if administered in the same period
B) Concurrent use reduces the antitumor efficacy of both agents
C) Trastuzumab accelerates anthracycline clearance, so concurrent dosing would be subtherapeutic
D) The two drugs compete for the topoisomerase II target and cancel each other's effect
E) Trastuzumab and anthracyclines have additive cardiotoxicity, so sequential rather than concurrent administration reduces the combined risk of heart failure
ANSWER: E
Rationale:
Trastuzumab and anthracyclines each stress the myocardium and their cardiotoxic effects are additive; giving them sequentially rather than concurrently lowers the combined heart-failure risk while preserving the benefit of each.
Option A: Option A is incorrect because the concern is additive biological cardiotoxicity in the patient, not chemical degradation of the anthracycline by trastuzumab.
Option B: Option B is incorrect because the rationale is cardiac safety, not loss of antitumor efficacy.
Option C: Option C is incorrect because trastuzumab does not accelerate anthracycline clearance, and the sequencing is not a pharmacokinetic dosing maneuver.
Option D: Option D is incorrect because trastuzumab targets HER2, not topoisomerase II, so they do not compete for a shared target.
11. [CASE 3 — QUESTION 3]
Continuing with the same patient. During anthracycline therapy, L.D.'s surveillance echocardiogram shows her left ventricular ejection fraction (LVEF) has fallen from a baseline of 60% to 46%, and she now reports mild exertional dyspnea. What is the most appropriate next step?
A) Continue the anthracycline at full dose, since a single low LVEF is not meaningful
B) Hold the anthracycline, obtain cardio-oncology consultation, and start an ACE inhibitor (or angiotensin receptor blocker) plus a beta-blocker, because a clinically significant LVEF decline below 50% signals anthracycline cardiotoxicity
C) Increase the anthracycline dose to finish therapy before further decline
D) Switch to bleomycin, which has no cardiac toxicity
E) Add dexrazoxane and continue the anthracycline unchanged with no other intervention
ANSWER: B
Rationale:
A drop in LVEF below 50% with a meaningful decline from baseline and new symptoms indicates anthracycline-induced cardiac dysfunction; the appropriate response is to hold the anthracycline, obtain cardio-oncology input, and start guideline-directed heart failure therapy (an ACE inhibitor or angiotensin receptor blocker plus a beta-blocker) to limit progression.
Option A: Option A is incorrect because a significant symptomatic decline below 50% is clinically important and cannot be dismissed.
Option C: Option C is incorrect because increasing the dose would worsen cumulative cardiotoxicity in a patient already showing injury.
Option D: Option D is incorrect because bleomycin is not a substitute for the anthracycline's antitumor role and carries serious pulmonary toxicity.
Option E: Option E is incorrect because simply adding dexrazoxane while continuing full-dose therapy ignores the need to hold treatment, involve cardiology, and start cardioprotective heart failure medications.
12. [CASE 3 — QUESTION 4]
Continuing with the same patient. After cardiac recovery and optimization, L.D. later has progressive disease that is still anthracycline-responsive, but she is now near the cumulative conventional doxorubicin-equivalent dose associated with substantial cardiac risk. The team wishes to continue anthracycline benefit while limiting further cardiac injury. Which option best accomplishes this, and what should she be counseled about?
A) Continue conventional doxorubicin past the cardiac ceiling because she is responding
B) Double the conventional doxorubicin dose to complete therapy quickly
C) Add bleomycin to allow lower anthracycline dosing
D) Switch to pegylated liposomal doxorubicin, which reduces cardiotoxicity and myelosuppression while introducing hand-foot syndrome (palmar-plantar erythrodysesthesia) as the main dose-limiting toxicity to counsel her about
E) Stop all anticancer therapy permanently because the anthracycline ceiling has been reached
ANSWER: D
Rationale:
Pegylated liposomal doxorubicin reduces cardiotoxicity and myelosuppression relative to conventional doxorubicin and remains active, making it a rational way to continue anthracycline benefit near the cardiac ceiling; the key counseling point is hand-foot syndrome, its characteristic dose-limiting toxicity, managed by dose reduction and cycle delay.
Option A: Option A is incorrect because continuing conventional doxorubicin past the ceiling courts irreversible cardiomyopathy.
Option B: Option B is incorrect because doubling the dose would accelerate cumulative cardiotoxicity.
Option C: Option C is incorrect because adding bleomycin (a pulmonary-toxic agent without a role here) does not solve the cardiac-ceiling problem and adds new risk.
Option E: Option E is incorrect because reaching the conventional anthracycline ceiling does not require abandoning all therapy; liposomal doxorubicin or other active agents remain options.
13. [CASE 4 — QUESTION 1]
A 78-year-old man, J.P., has extensive-stage small cell lung cancer, a poor performance status, and comorbidities that preclude an intensive intravenous platinum-based combination. The oncologist wishes to use etoposide in the way most likely to produce a response given his frailty. Which approach is most rational, and why?
A) Use a prolonged, divided oral etoposide schedule over several days, exploiting the drug's schedule dependency to sustain exposure during the topoisomerase II-vulnerable window and improve response compared with bolus dosing
B) Give a single large intravenous bolus to minimize clinic visits, since peak concentration drives efficacy
C) Withhold etoposide entirely because it has no activity without cisplatin
D) Administer etoposide once every six weeks at very high dose
E) Replace etoposide with bleomycin, which is better tolerated in the elderly
ANSWER: A
Rationale:
Etoposide is schedule-dependent, so dividing the same total dose into prolonged lower-dose exposure sustains drug levels across more of the cell-cycle window in which topoisomerase II is active and yields higher response rates than an equivalent bolus; a prolonged oral schedule is therefore a rational, better-tolerated choice for a frail elderly patient who cannot receive intensive intravenous combinations.
Option B: Option B is incorrect because a single large bolus does not exploit schedule dependency and is generally less effective; etoposide efficacy is not peak-driven.
Option C: Option C is incorrect because single-agent etoposide has activity and is a legitimate option when platinum doublets cannot be given.
Option D: Option D is incorrect because infrequent very-high-dose administration is the opposite of the sustained-exposure approach that benefits etoposide.
Option E: Option E is incorrect because bleomycin is not an appropriate substitute for etoposide in small cell lung cancer and carries serious pulmonary toxicity, especially in the elderly.
14. [CASE 4 — QUESTION 2]
Continuing with the same patient. A trainee asks how etoposide actually kills the tumor cells in J.P.'s regimen. Which statement most precisely describes etoposide's molecular mechanism?
A) It intercalates DNA and generates reactive oxygen species that cleave strands
B) It inhibits topoisomerase I by trapping the single-strand cleavable complex
C) It stabilizes the topoisomerase II cleavable complex, preventing religation and leaving persistent double-strand breaks that trigger the DNA damage response and apoptosis
D) It cross-links guanine bases on opposite DNA strands
E) It blocks RNA polymerase by intercalating at GC base pairs
ANSWER: C
Rationale:
Etoposide is a topoisomerase II poison: it binds and stabilizes the Topo II-DNA cleavable complex after the enzyme has cut both strands, preventing religation and leaving persistent double-strand breaks that activate the DNA damage response and apoptosis.
Option A: Option A is incorrect because reactive oxygen species generation with intercalation describes the anthracyclines and bleomycin, not etoposide's primary mechanism.
Option B: Option B is incorrect because trapping the single-strand cleavable complex describes the camptothecins acting on topoisomerase I.
Option D: Option D is incorrect because interstrand guanine cross-linking describes alkylating agents and platinum compounds.
Option E: Option E is incorrect because blocking RNA polymerase by GC intercalation describes actinomycin D, not etoposide.
15. [CASE 4 — QUESTION 3]
Continuing with the same patient. J.P. responds and survives well beyond expectation. About two years after his etoposide-containing therapy, he develops fatigue, pancytopenia, and circulating blasts, with no antecedent period of cytopenias suggesting myelodysplasia. Bone marrow examination confirms acute myeloid leukemia. Which mechanism best explains this development, and what cytogenetic finding would support it?
A) Cisplatin-induced leukemia, supported by an expected Philadelphia chromosome
B) An incidental de novo leukemia unrelated to any prior therapy, with no characteristic cytogenetics
C) Alkylating-agent-related leukemia, supported by monosomy 7 with long latency and a preceding myelodysplastic phase
D) Bleomycin-induced marrow injury, supported by trisomy 21
E) Topoisomerase II poison (etoposide)-related secondary acute myeloid leukemia, supported by a balanced MLL gene rearrangement at chromosome 11q23 with short latency and no preceding myelodysplastic phase
ANSWER: E
Rationale:
A short latency of roughly two years, an abrupt leukemic presentation without a preceding myelodysplastic phase, and prior etoposide exposure are the signature of topoisomerase II poison-related acute myeloid leukemia, supported by a balanced MLL rearrangement at 11q23.
Option A: Option A is incorrect because cisplatin is not the classic cause of this pattern, and the Philadelphia chromosome defines chronic myeloid leukemia, not this entity.
Option B: Option B is incorrect because the presentation fits a therapy-related leukemia with a characteristic cytogenetic signature, not an incidental de novo process.
Option C: Option C is incorrect because monosomy 7 with long latency and a preceding myelodysplastic phase characterizes alkylating-agent leukemia, the contrasting pattern.
Option D: Option D is incorrect because bleomycin is marrow-sparing and not leukemogenic in this pattern, and trisomy 21 is not the relevant finding.
16. [CASE 4 — QUESTION 4]
Continuing with the same patient. Reflecting on J.P.'s course, a junior colleague asks how the risk of treatment-related leukemia should have been handled at the outset, when etoposide was first proposed. Which statement best captures the appropriate approach to this risk during informed consent for a curative-intent or life-prolonging etoposide-containing regimen?
A) The secondary-leukemia risk is so negligible that it need not be mentioned during consent
B) The small but real cumulative risk of treatment-related acute myeloid leukemia from etoposide should be disclosed during informed consent, weighed against the substantial survival benefit of the regimen, since the benefit typically outweighs the leukemia risk in curative-intent or life-prolonging treatment
C) Etoposide should be avoided entirely in all patients because any leukemia risk is unacceptable
D) The leukemia risk can be eliminated by giving etoposide only by the oral route
E) The risk applies only to pediatric patients and is irrelevant to adult consent discussions
ANSWER: B
Rationale:
Treatment-related acute myeloid leukemia from etoposide is a small but real cumulative risk that should be disclosed during informed consent and weighed against the regimen's benefit; in curative-intent or meaningfully life-prolonging therapy, the survival benefit typically outweighs the leukemia risk, and honest disclosure allows shared decision-making.
Option A: Option A is incorrect because the risk is real and meaningful enough to warrant disclosure, not omission.
Option C: Option C is incorrect because avoiding etoposide entirely would deny patients an effective, often curative agent; the risk is managed through disclosure and appropriate use, not blanket avoidance.
Option D: Option D is incorrect because the secondary-leukemia risk relates to etoposide exposure itself and is not eliminated by the oral route.
Option E: Option E is incorrect because the risk applies to adults as well, so it is relevant to adult consent discussions.
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