What is the post-CT scan management for patients with seminoma and non-seminomatous germ cell tumors (NSGCT), specifically regarding the evaluation of retroperitoneal lymph nodes (RPLN) and residual lesions?

Post-Chemotherapy Management of Seminoma and Non-Seminomatous Germ Cell Tumors

Key Distinction in Post-CT Management

For seminoma, only residual masses >3 cm require evaluation with FDG-PET scan, and patients with complete response need no further intervention; for NSGCT, any residual retroperitoneal lymph node >1 cm mandates surgical resection regardless of location. 1

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Seminoma Post-Chemotherapy Management

Complete Response

• Patients achieving complete radiographic response after chemotherapy require no additional treatment—neither surgery nor radiotherapy. 1, 2
• This applies regardless of initial tumor bulk or stage at presentation. 1

Residual Masses ≤3 cm

• Observation only with routine surveillance imaging is appropriate. 2
• No surgical intervention or PET scanning is indicated for masses ≤3 cm. 2

Residual Masses >3 cm

• FDG-PET scan should be performed at least 6 weeks after completion of chemotherapy (critical timing to avoid false positives from inflammation). 1, 2
• If PET-negative: surveillance only without surgery or radiotherapy. 2
• If PET-positive: consider surgical resection rather than consolidation radiotherapy. 2

Critical Pitfall

• Do not perform PC-RPLND routinely in seminoma patients—this is associated with significant morbidity and is only indicated for PET-positive residual masses where surgery is technically feasible. 3

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Non-Seminomatous Germ Cell Tumor Post-Chemotherapy Management

Normalized Tumor Markers Required

• Post-chemotherapy RPLND is only indicated when serum tumor markers (AFP, β-hCG) have normalized after chemotherapy. 1
• Persistently elevated or rising markers indicate active disease requiring salvage chemotherapy, not surgery. 1

Residual Mass Size Threshold

• Any residual retroperitoneal lymph node ≥1 cm in axial diameter mandates surgical resection via full bilateral template RPLND. 1
• This is non-negotiable due to the 40-50% risk of viable cancer or teratoma in residual masses. 1

Residual Masses <1 cm

• Management remains controversial for masses <1 cm with normalized markers. 4
• Options include surveillance with serial imaging or nerve-sparing RPLND. 4
• The presence of teratoma in the primary tumor increases the indication for surgery even with small residual masses. 5

Complete Radiographic Response

• Patients achieving complete radiographic response (no visible masses) with normalized markers can be observed without surgery, regardless of initial retroperitoneal bulk. 5
• This applies even to patients who presented with bulky adenopathy initially. 5

Surgical Principles for PC-RPLND

• Full bilateral template dissection is mandatory in the post-chemotherapy setting—modified templates increase in-field recurrence risk. 1
• Boundaries: renal hilar vessels (superior), ureters (lateral), common iliac arteries (inferior). 1
• Surgical margins should not be compromised to preserve ejaculation—completeness of resection is the primary predictor of survival. 1
• Referral to high-volume centers is strongly recommended. 1

Extra-Retroperitoneal Residual Masses

• All extra-retroperitoneal residual masses (pulmonary, mediastinal, neck) require surgical resection if >1 cm, regardless of location. 1
• Multiple visceral metastases should be evaluated at expert centers for coordinated surgical approach. 1

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Algorithm for Post-CT Decision Making

For Seminoma:

1. Assess radiographic response
2. If complete response → surveillance only
3. If residual mass ≤3 cm → surveillance only
4. If residual mass >3 cm → FDG-PET at 6+ weeks post-CT
   • PET negative → surveillance
   • PET positive → consider surgical resection

For NSGCT:

1. Confirm tumor markers normalized (AFP, β-hCG)
2. If markers elevated/rising → salvage chemotherapy (not surgery)
3. If markers normal:
   • Complete radiographic response → surveillance
   • Residual retroperitoneal mass ≥1 cm → full bilateral RPLND
   • Residual mass <1 cm → surveillance vs. RPLND (consider teratoma in primary)
   • Any extra-retroperitoneal mass ≥1 cm → surgical resection

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Common Pitfalls to Avoid

• Do not apply NSGCT surgical principles to seminoma—seminoma rarely requires PC-RPLND and the 1 cm threshold does not apply. 1, 3
• Do not perform PET scanning in NSGCT—it has no role in post-chemotherapy evaluation of non-seminomatous tumors. 1
• Do not delay PC-RPLND in NSGCT beyond 4-6 weeks after marker normalization—teratoma can grow during observation. 1
• Do not use modified template dissections in the post-chemotherapy setting—full bilateral dissection is required regardless of pre-chemotherapy disease distribution. 1