CONCEPTUAL SUMMARY
- Definition and Classification: Sarcomas are rare malignant tumors of mesenchymal origin (connective tissue: muscle, bone, fat, vessels, nerves), representing approximately 1% of adult cancers with over 70 histologic subtypes. Soft tissue sarcomas (STS) account for ~80% of cases; bone sarcomas account for ~20%. The most common adult STS subtypes are undifferentiated pleomorphic sarcoma (UPS), liposarcoma, leiomyosarcoma, and synovial sarcoma.
- Epidemiology and Risk Factors: Approximately 13,000 cases per year in the US. Peak incidence in the 4th–6th decade. Risk factors include prior radiation, genetic syndromes (Li-Fraumeni, NF1, WAGR), chronic lymphedema, and environmental exposures.
- Diagnosis and Staging: Requires core needle biopsy, imaging (MRI for local extent, CT chest for metastases), and multidisciplinary sarcoma board review. Subtype confirmation uses immunohistochemistry and molecular testing (MDM2 for dedifferentiated liposarcoma, KIT/PDGFRA for GIST, SS18::SSX for synovial sarcoma, NTRK fusions). Staging uses AJCC TNM + FNCLCC grade. Prognosis is influenced by size, grade, depth, histology, and metastases (lungs most common). A bone scan has NO role in staging soft tissue sarcomas.
- Treatment (Localized Disease): Surgery is the cornerstone — goal is negative margins. Radiation (neoadjuvant or adjuvant) improves local control in STS. Chemotherapy is controversial in localized disease but may be used in high-grade/large tumors (doxorubicin ± ifosfamide). Adjuvant chemo for localized STS has been shown to decrease risk of relapse but NOT definitively improve overall survival.
Treatment (Advanced/Metastatic STS)
- First-line: doxorubicin single-agent (standard); combined with ifosfamide for fit patients requiring tumor shrinkage.
- Subtype-specific second-line and beyond:
- liposarcoma → eribulin (especially dedifferentiated/pleomorphic), trabectedin (especially myxoid);
- leiomyosarcoma → gemcitabine/docetaxel (preferred for uterine LMS), trabectedin; synovial sarcoma → high-dose ifosfamide (salvage), pazopanib; angiosarcoma → weekly paclitaxel, bevacizumab (off-label); UPS → doxorubicin-based chemo, checkpoint inhibitors (pembrolizumab) showing activity. Pazopanib is approved for NON-adipocytic STS only — NOT for liposarcoma/adipocytic tumors.
Treatment (Bone Sarcomas)
- Osteosarcoma: MAP regimen — high-dose methotrexate + doxorubicin (Adriamycin) + cisplatin, perioperative (neoadjuvant + adjuvant). HD-MTX is generally reserved for patients under 40; older patients receive cisplatin + doxorubicin without HD-MTX.
- Ewing sarcoma: VDC/IE — vincristine + doxorubicin + cyclophosphamide alternating with ifosfamide + etoposide every 2 weeks (interval compression per AEWS0031). Curative treatment of localized osteosarcoma requires BOTH chemotherapy and surgical resection — radiation has NO curative role.
GIST Risk Stratification and Adjuvant Therapy:
Low-risk GIST features: mitotic index < 5 per 50 HPF, small size, gastric location, no rupture. High-risk features: mitotic index ≥ 5 per 50 HPF, large size (> 5 cm), non-gastric location, tumor rupture. Adjuvant imatinib: 1 year for low/intermediate-risk disease; 3 years for high-risk disease (3 years improved OS vs. 1 year). KIT exon 9 mutation: requires imatinib 400 mg TWICE daily (double standard dose) for metastatic disease when progressing on standard dose. GIST treatment sequence: imatinib → sunitinib → regorafenib → ripretinib. Avapritinib: for PDGFRA exon 18 mutations (especially D842V) — NOT appropriate for KIT-mutated GIST.
High-Dose Methotrexate (HD-MTX) Management: Requires leucovorin rescue + urine alkalinization (pH > 7, NOT < 7) + plasma MTX level monitoring. Thiazide diuretics must be HELD for at least 2 days before MTX and until after clearance. Pleural effusions cause third-spacing — delay HD-MTX until resolved, or if given, require prolonged leucovorin rescue. 48-hour MTX level > 5 µM → increase leucovorin. 48-hour MTX level elevation + serum creatinine doubled from baseline → start glucarpidase (carboxypeptidase G2). Dexrazoxane has NO role in MTX clearance — it is for doxorubicin extravasation and cardioprotection.
Ifosfamide Supportive Care: Mesna is MANDATORY to prevent hemorrhagic cystitis (binds acrolein in urinary tract). Hydration with NORMAL SALINE (NOT sodium bicarbonate — no added urothelial protection). Standard mesna dosing: IV in 3 divided doses — first dose 15 minutes BEFORE ifosfamide, second dose 4 hours after, third dose 8 hours after. Oral mesna is 50% bioavailable — dose must be DOUBLED if given orally. If oral mesna is vomited within 2 hours — repeat the dose. Urine must be tested for red blood cells BEFORE each dose of ifosfamide. Ifosfamide also causes encephalopathy (neuro monitoring required) and nephrotoxicity.
Key Drug Toxicities:
- Doxorubicin: cardiotoxicity (cumulative dose-dependent, limit 450–550 mg/m²); monitor LVEF; consider dexrazoxane if > 300 mg/m² at high cardiac risk.
- Trabectedin: hepatotoxicity (monitor LFTs), rhabdomyolysis; requires dexamethasone premedication; CYP3A4 substrate.
- Pazopanib: hepatotoxicity, hypertension, diarrhea, hand-foot syndrome, QT prolongation; monitor LFTs frequently early; many CYP3A4 interactions.
- Eribulin: neutropenia, peripheral neuropathy, QT prolongation; dose adjustments for hepatic impairment.
- Imatinib: edema, nausea, myelosuppression, hepatotoxicity, rash; monitor LFTs and CBC; emphasize adherence.
- Pexidartinib (for TGCT/PVNS): hepatotoxicity — remains on REMS program; take with LOW-FAT MEAL; reduces symptoms but does NOT cure PVNS.
PRACTICE QUESTIONS
W.H. is a 55-year-old man with a high-grade, 5 cm synovial sarcoma of the right forearm who underwent surgery with positive margins, followed by adjuvant radiation therapy. The multidisciplinary team recommends chemotherapy. Which of the following statements regarding post-operative chemotherapy should be included in your discussion?
A. Post-operative chemotherapy improves survival
B. Post-operative chemotherapy decreases risk for relapse
C. Post-operative chemotherapy increases risk of distant recurrence
D. Post-operative chemotherapy improves survival and decreases risk for local recurrence
Explanation: Adjuvant chemotherapy in localized high-grade soft tissue sarcoma has been shown to decrease the risk of relapse (both local and distant recurrence). However, it has NOT been shown to definitively improve overall survival in meta-analyses. It does NOT increase the risk of distant recurrence (option C is incorrect). Stating it improves survival (options A and D) overstates the evidence — survival benefit remains controversial and is not the established claim.
[/expand]W.H. has a high-grade synovial sarcoma of the right forearm treated with surgery (positive margins) and adjuvant radiation. The team recommends adjuvant chemotherapy. Which chemotherapy agents should be part of W.H.'s adjuvant regimen?
A. Gemcitabine
B. Pazopanib
C. Ifosfamide and doxorubicin
D. Ifosfamide and dacarbazine
Explanation: The most active regimen for synovial sarcoma is doxorubicin + ifosfamide (AIM regimen). Doxorubicin and ifosfamide are the two most studied and most active cytotoxic agents for synovial sarcoma in both the adjuvant and metastatic settings. Gemcitabine alone (option A) is not the standard for synovial sarcoma. Pazopanib (option B) is a TKI used as a later-line option — it has no established role in the adjuvant setting. Ifosfamide + dacarbazine (option D) is not the established standard combination for synovial sarcoma.
[/expand]WJ is a 45-year-old man with high-grade synovial sarcoma, positive margins, treated with adjuvant radiation. He has ECOG 0 and no significant comorbidities. The team recommends adjuvant chemotherapy. Which chemotherapy agents should be part of WJ's adjuvant regimen?
A. Gemcitabine and docetaxel
B. Regorafenib
C. Ifosfamide and doxorubicin
D. Doxorubicin alone
Explanation: Given WJ's age, high tumor grade, positive margins, and excellent performance status (ECOG 0), combination chemotherapy with doxorubicin + ifosfamide is the most appropriate approach. Single-agent doxorubicin (option D) did not demonstrate a statistically significant survival benefit in the 2008 meta-analysis for localized STS. Gemcitabine/docetaxel (option A) is preferred for leiomyosarcoma, not synovial sarcoma. Regorafenib (option B) is a TKI used for GIST and has no established adjuvant role in synovial sarcoma.
[/expand]JR is a 38-year-old female who undergoes successful resection of a 3 cm intestinal GIST. Pathology: cKIT exon 9 mutation (A502_Y503dup) positive, 4 mitoses per 50 high-power fields. What is the best adjuvant treatment for JR?
A. Imatinib for 1 year
B. Imatinib for 3 years
C. Avapritinib for 1 year
D. Sunitinib for 3 years
Explanation: JR's tumor is low-risk for recurrence — the intestinal tumor is 3 cm (small) with a mitotic index of 4/50 HPF (< 5/50 HPF = low mitotic rate). Low-risk patients receive 1 year of adjuvant imatinib. JR is cKIT positive, making imatinib appropriate. Avapritinib (option C) is indicated for PDGFRA exon 18 mutations (especially D842V) and is not approved in the adjuvant setting. Sunitinib (option D) is not approved in the adjuvant setting. Three years of imatinib (option B) is reserved for high-risk patients (large size, high mitotic index, non-gastric location, or rupture).
[/expand]MR is a 48-year-old man who undergoes successful resection of a 6 cm gastric GIST. Pathology: cKIT positive, 7 mitoses per 50 high-power fields. What is the best adjuvant treatment for MR?
A. Imatinib for 1 year
B. Imatinib for 3 years
C. Sunitinib for 1 year
D. Sunitinib for 3 years
Explanation: MR has a high-risk gastric GIST — the tumor is 6 cm AND has a mitotic rate of 7/50 HPF (≥ 5/50 HPF). Both features independently confer high recurrence risk. For high-risk patients, 3 years of adjuvant imatinib is standard — the SSG XVIII trial demonstrated that 3 years improved overall survival compared to 1 year. MR is cKIT positive, confirming imatinib sensitivity. Sunitinib is NOT approved in the adjuvant setting (options C and D are incorrect).
[/expand]JR returns 5 years after completing adjuvant imatinib with recurrent unresectable gastric GIST. Her tumor remains cKIT exon 9 mutation positive. She was restarted at an outside center on imatinib 400 mg daily and is tolerating it well, but now has progressive disease. Which therapy is most appropriate to recommend for JR at this time?
A. Imatinib 400 mg twice daily
B. Avapritinib 300 mg daily
C. Regorafenib 160 mg daily (3 weeks on, 1 week off)
D. Ripretinib 150 mg daily
Explanation: JR has a KIT exon 9 mutation — this mutation specifically benefits from higher-dose imatinib at 400 mg TWICE daily (800 mg total daily). She is progressing on standard-dose imatinib 400 mg daily without intolerance, so dose escalation to 800 mg/day is the appropriate next step. Avapritinib (option B) is indicated for PDGFRA exon 18 mutations only — not for KIT-mutated GIST. Regorafenib (option C) is approved for metastatic GIST but is reserved for third-line therapy (after imatinib AND sunitinib failure). Ripretinib (option D) is fourth-line (after ≥ 3 prior TKIs) — JR has not yet received sunitinib.
[/expand]PL is a 63-year-old male with synovial sarcoma scheduled to start ifosfamide 1500 mg/m²/day on days 1–4 and doxorubicin 20 mg/m²/day on days 1–3. What supportive care is required for PL's chemotherapy?
A. Mesna only
B. Mesna and hydration with sodium bicarbonate
C. Mesna and hydration with normal saline
D. Hydration with sodium bicarbonate
Explanation: Ifosfamide-based therapy ALWAYS requires mesna (to prevent hemorrhagic cystitis by binding the toxic acrolein metabolite) AND aggressive IV hydration with normal saline. Sodium bicarbonate added to hydration fluids has NOT been shown to provide additional urothelial protection and is therefore not recommended. Mesna alone without hydration (option A) is insufficient. Sodium bicarbonate-based hydration (options B and D) is not the standard of care for ifosfamide uroprotection.
[/expand]PL is a 55-year-old male with synovial sarcoma starting the AIM regimen (doxorubicin, ifosfamide, and mesna). Which of the following counseling points is most appropriate for PL while he receives the AIM regimen?
- Samples of your urine will be tested for the presence of red blood cells prior to each dose of ifosfamide
- Report shortness of breath to your healthcare provider because it could represent heart toxicity
- If a dose of oral mesna is vomited after 30 or more minutes have elapsed, there is no need to repeat the dose
- Oral mesna should be taken 12 hours after the last dose of ifosfamide
Explanation:
- Urine is tested for red blood cells (microscopic hematuria) BEFORE each ifosfamide dose because the presence of blood indicates hemorrhagic cystitis and may warrant a delay or dose modification. This is a critical patient counseling point.
- Option B is incorrect — the relevant ifosfamide toxicity to counsel patients about is neurotoxicity (encephalopathy: confusion, blurred vision), not cardiac toxicity.
- Option C is incorrect — if oral mesna is vomited within 2 HOURS (not 30 minutes), the dose must be repeated.
- Option D is incorrect — standard mesna dosing is at 0 hours (15 min before or concurrent), 4 hours after, and 8 hours after ifosfamide — NOT 12 hours after.
PL is a 55-year-old male with synovial sarcoma starting ifosfamide 1500 mg/m²/day IV on days 1–4 and doxorubicin 20 mg/m²/day IV on days 1–3. What additional supportive care is required for PL's chemotherapy?
- Mesna 500 mg/m² IV in 3 divided doses: 15 minutes prior to ifosfamide, 4 hours after, and 8 hours after
- Mesna 500 mg/m² PO in 3 divided doses: 15 minutes prior to ifosfamide, 4 hours after, and 8 hours after — plus hydration with normal saline
- Mesna 500 mg/m² IV in 3 divided doses: 15 minutes prior to ifosfamide, 4 hours after, and 8 hours after — plus hydration with normal saline
- Hydration with sodium bicarbonate
Explanation: IV mesna at 0 (15 minutes before), 4, and 8 hours after ifosfamide plus normal saline hydration is the correct supportive care. Option A lacks hydration — hydration is mandatory. Option B is incorrect because oral mesna is only 50% bioavailable — if oral mesna is used, the dose must be DOUBLED. At 500 mg/m² oral, the patient would receive only 50% of the intended mesna exposure, which is inadequate. Sodium bicarbonate hydration (option D) has no proven additional urothelial benefit.
[/expand]TB is a 54-year-old male with a 4 cm high-grade osteosarcoma of the left tibia. The treatment plan is neoadjuvant chemotherapy followed by surgery. Which regimen is most appropriate for neoadjuvant therapy for TB?
A. Cisplatin and doxorubicin
B. High-dose methotrexate, cisplatin, and ifosfamide
C. Cyclophosphamide and topotecan
D. Ifosfamide and etoposide
Explanation: TB is 54 years old — HD-MTX (high-dose methotrexate) is generally reserved for patients UNDER 40. For older patients, the standard neoadjuvant regimen is cisplatin + doxorubicin without HD-MTX. Option B (HD-MTX + cisplatin + ifosfamide) uses HD-MTX, which is not standard for patients over 40 due to increased toxicity risk without a clear added benefit. Cyclophosphamide + topotecan (option C) and ifosfamide + etoposide (option D) are considered for recurrent/refractory osteosarcoma, not as first-line neoadjuvant therapy.
[/expand]TB is a 34-year-old male with a 4 cm high-grade osteosarcoma of the left tibia. The treatment plan is neoadjuvant chemotherapy followed by surgery. Which regimen is most appropriate for neoadjuvant therapy for TB?
A. High-dose methotrexate, cisplatin, and doxorubicin
B. High-dose methotrexate, cisplatin, and ifosfamide
C. Cyclophosphamide and topotecan
D. Regorafenib
Explanation: TB is 34 years old — for patients UNDER 40, the standard MAP regimen (high-dose methotrexate + doxorubicin + cisplatin) is the preferred neoadjuvant regimen for osteosarcoma, based on the COSS and EURAMOS trials. HD-MTX + cisplatin + ifosfamide (option B) substitutes ifosfamide for doxorubicin — this is not the standard first-line MAP regimen. Cyclophosphamide + topotecan (option C) and regorafenib (option D) are for relapsed/refractory settings.
[/expand]TB is a 34-year-old male receiving HD-MTX 12,000 mg/m² IV over 4 hours as part of MAP chemotherapy. At 48 hours post-infusion, his methotrexate level is 5.1 µM. Baseline serum creatinine was 0.9 mg/dL; current creatinine is 1.2 mg/dL. What is the most appropriate treatment recommendation at this time?
A. Increase leucovorin
B. Start glucarpidase
C. Increase sodium bicarbonate infusion to obtain a urine pH > 8
D. Start dexrazoxane
Explanation: The 48-hour MTX level of 5.1 µM is elevated (> 5 µM = delayed clearance threshold requiring leucovorin dose increase). However, the creatinine has only risen from 0.9 to 1.2 mg/dL — a modest increase that does NOT yet meet the threshold for glucarpidase (which requires evidence of significant renal dysfunction with delayed MTX clearance). Increasing leucovorin is the appropriate immediate action. Glucarpidase (option B) is reserved for delayed clearance WITH significant renal impairment (creatinine ≥ doubled from baseline with markedly elevated MTX levels). Increasing sodium bicarbonate alone (option C) is insufficient without leucovorin dose escalation. Dexrazoxane (option D) has NO role in MTX clearance.
[/expand]TB is a 34-year-old male receiving HD-MTX 12,000 mg/m² IV over 4 hours as part of MAP chemotherapy. At 48 hours post-infusion, his methotrexate level is 6.8 µM. Baseline serum creatinine was 0.9 mg/dL; current creatinine is 2.7 mg/dL. What is the most appropriate treatment recommendation at this time?
A. Increase leucovorin
B. Start glucarpidase
C. Increase sodium bicarbonate infusion to obtain a urine pH > 8
D. Start dexrazoxane
Explanation: This patient has two critical indicators for glucarpidase: a 48-hour MTX level of 6.8 µM (significantly elevated, well above the 5 µM threshold) AND the serum creatinine has risen from 0.9 to 2.7 mg/dL — approximately tripled from baseline, indicating significant renal impairment impairing MTX clearance. Glucarpidase (carboxypeptidase G2) rapidly cleaves methotrexate into inactive metabolites, providing immediate rescue. Leucovorin should be continued alongside glucarpidase but is insufficient alone given the degree of renal impairment. Sodium bicarbonate alone (option C) cannot adequately reduce MTX levels with this degree of renal dysfunction. Dexrazoxane (option D) has no role in MTX clearance.
[/expand]JS is a 25-year-old male with metastatic osteosarcoma admitted to start his first dose of high-dose methotrexate as part of MAP. He is on a thiazide diuretic and is noted to have a pleural effusion on imaging. What is the most appropriate recommendation at this time?
- Start premedications to alkalinize the urine to pH < 7 prior to methotrexate initiation
- Hold the patient's thiazide diuretic for at least 2 days prior to methotrexate and until after clearance
- Reassure the team that the patient's pleural effusion will not affect methotrexate clearance
- Restrict fluid intake
Explanation:
- Thiazide diuretics impair methotrexate renal clearance and must be HELD for at least 2 days before HD-MTX administration and until methotrexate has fully cleared.
- Option A is incorrect — urine must be alkalinized to pH > 7 (NOT < 7) — acidic urine promotes MTX crystallization in renal tubules.
- Option C is incorrect — pleural effusions cause third-space sequestration of methotrexate, significantly increasing its volume of distribution and prolonging its terminal half-life; HD-MTX should ideally be deferred until the effusion resolves.
- Option D is incorrect — hydration should be ENCOURAGED to facilitate methotrexate clearance, not restricted.
JS is a 25-year-old male with metastatic osteosarcoma who received HD-MTX 12,000 mg/m² IV over 4 hours. At 48 hours, his MTX level is 5.1 µM. Baseline creatinine was 0.9 mg/dL; current creatinine is 1.2 mg/dL. What is the most appropriate treatment recommendation at this time?
A. Increase leucovorin
B. Start glucarpidase
C. Increase sodium bicarbonate infusion to obtain a urine pH > 8
D. Start dexrazoxane
Explanation: The 48-hour MTX level of 5.1 µM exceeds the threshold of 5 µM, indicating delayed clearance requiring leucovorin dose escalation. The creatinine has increased modestly from 0.9 to 1.2 mg/dL — insufficient to warrant glucarpidase at this time. Increasing leucovorin is the appropriate immediate action to prevent MTX-related toxicity (mucositis, myelosuppression, nephrotoxicity). Glucarpidase (option B) requires more significant renal impairment with markedly elevated MTX levels. Sodium bicarbonate alone (option C) is insufficient without leucovorin escalation. Dexrazoxane (option D) is for doxorubicin cardioprotection/extravasation — NO role in MTX clearance.
[/expand]SM is a 33-year-old female with tenosynovial giant cell tumor (TGCT)/pigmented villonodular synovitis (PVNS) who opts to start pexidartinib. Which of the following is an important counseling point for SM?
A. Take the pexidartinib on an empty stomach
B. Take the pexidartinib with a low-fat meal
C. This drug has been removed from its REMS program
D. This treatment will cure your PVNS
Explanation:
- Pexidartinib should be taken with a LOW-FAT meal to enhance absorption while minimizing the risk of adverse effects.
- Option A is incorrect — an empty stomach is not the correct administration instruction.
- Option C is incorrect — pexidartinib remains on a REMS (Risk Evaluation and Mitigation Strategy) program specifically because of its risk of serious hepatotoxicity (including fatal cases); liver function must be closely monitored throughout therapy.
- Option D is incorrect — pexidartinib reduces symptoms and tumor burden in TGCT/PVNS but does NOT cure the disease.
Which of the following is NOT a common side effect of imatinib?
A. Periorbital edema
B. Fatigue
C. Liver function test abnormalities
D. Neuropathy
E. Muscle cramps
Explanation: The common side effects of imatinib include periorbital and peripheral edema, fatigue, nausea, liver function test abnormalities (hepatotoxicity), rash, myelosuppression, and muscle cramps. Neuropathy is NOT a characteristic side effect of imatinib — it is associated with vincristine, taxanes, platinum agents, and thalidomide/lenalidomide. The absence of significant neurotoxicity is actually one of the notable features distinguishing imatinib from many other chemotherapy agents.
[/expand]All of the following treatments could be considered for a patient with metastatic liposarcoma EXCEPT:
A. Doxorubicin
B. Ifosfamide
C. Eribulin
D. Pazopanib
Explanation:
- Pazopanib is FDA-approved for NON-ADIPOCYTIC soft tissue sarcomas after prior chemotherapy — it is specifically EXCLUDED from use in liposarcoma (an adipocytic tumor) based on the PALETTE trial design and FDA label.
- Doxorubicin (option A) is first-line for all advanced STS including liposarcoma.
- Ifosfamide (option B) is active in multiple STS subtypes including liposarcoma.
- Eribulin (option C) is specifically FDA-approved for liposarcoma — particularly dedifferentiated and pleomorphic subtypes — based on the Phase III trial showing improved overall survival.
A 55-year-old man presents with a firm, painless, enlarging mass on his left thigh. Biopsy reveals an undifferentiated pleomorphic sarcoma. Which is the next step in management?
A. Doxorubicin and ifosfamide
B. Surgical resection
C. MRI of the left lower extremity and CT chest
D. Bone scan
Explanation: Before any treatment decision, accurate staging is required. MRI of the affected extremity defines the local extent of the tumor (size, depth, neurovascular involvement — critical for surgical planning), while CT chest screens for pulmonary metastases (the most common site of STS metastases). This staging workup allows for accurate TNM staging and a multidisciplinary treatment plan. Jumping to chemotherapy (option A) or surgery (option B) before staging is inappropriate. Bone scan (option D) has NO established role in the routine staging of soft tissue sarcomas.
[/expand]A 22-year-old woman presents with pain in her right posterior chest wall. CT demonstrates a 7.1 × 6.5 × 5.5 cm mass arising from the right eighth rib. No lung nodules are noted. CT-guided biopsy reveals high-grade osteosarcoma. Bone scan shows uptake in the right eighth rib only — no other metastatic sites. What is the best treatment plan for this patient?
A. Methotrexate, doxorubicin, and cisplatin followed by surgery
B. Chemotherapy alone
C. Surgery alone
D. Radiation followed by surgery
E. Best supportive care
Explanation: This patient has localized osteosarcoma (no distant metastases). The optimal treatment for localized osteosarcoma requires BOTH neoadjuvant chemotherapy AND surgical resection — neither alone is appropriate. The MAP regimen (high-dose methotrexate + doxorubicin + cisplatin) followed by surgery is the standard of care. She is 22 years old — HD-MTX is appropriate for patients under 40. Chemotherapy alone (option B) without surgery is insufficient for curative intent. Surgery alone (option C) without chemotherapy significantly reduces cure rates. Radiation (option D) has no established curative role in osteosarcoma. Best supportive care (option E) is inappropriate for a young patient with potentially curable localized disease.
[/expand]Which of the following is a feature of a LOW-RISK gastrointestinal stromal tumor (GIST)?
A. Ileal location
B. Mitotic index < 5 per 50 high-powered fields
C. Size > 10 cm
D. Tumor rupture
Explanation: A low mitotic index (< 5 mitoses per 50 high-powered fields) is a key feature associated with LOW-RISK GIST — indicating slow tumor proliferation and low recurrence potential. Non-gastric location such as ileal location (option A) is actually an ADVERSE prognostic feature — gastric location carries a better prognosis than small intestinal tumors. Large size > 10 cm (option C) is a HIGH-RISK feature. Tumor rupture (option D) is one of the strongest high-risk features — it essentially upstages all tumors to high risk regardless of size or mitotic rate due to the high risk of peritoneal spread.
[/expand]19. RR is a 25-year-old female with osteosarcoma who is started on MAP (high-dose methotrexate. cisplatin, and doxorubicin). As part of her regimen, RR should receive leucovorin 15 mg IV q6h starting 24 hours after the start of the methotrexate (MTX) infusion and continued until the MTX level is less than 0.1 micromol/L. Unfortunately, there is a leucovorin shortage, and only levolucovorin is available.
Which dose of levolucovorin is appropriate for RR?
- A 7.5 mg IV q6h (70%)
- B 10 mg IV q6h (9%)
- C 15 mg IV q6h (8%)
- D 30 mg IV q6h (12%)
- The dose of levoleucovorin is equivalent to 50% of the leucovorin dose. Thus, 15 mg IV q6h leucovorin - 7.5 mg IV q6h levoleucovorin.
- Due to the current leucovorin shortage in the United States, patients can be switched from levocabotin to levoleucovorin, which is commonly used in Europe. The dose of levoleucovorin is equivalent to 50% of the dose of standard leucovorin.
- Leucovorin is used in conjunction with fluorouracil for the synergistic effect, whereas leucovorin is administered after high-dose MTX to rescue normal cells from MTX-induced toxicities.