Differences Between Seminoma and Non-seminoma: Treatment and Prognosis
Seminoma and non-seminoma differ significantly in treatment approaches and prognosis, with seminoma generally having better outcomes and more treatment options including radiotherapy, while non-seminoma requires more aggressive management and has higher relapse rates.
Pathological and Clinical Characteristics
- Seminoma and non-seminoma represent the two main histological subtypes of testicular germ cell tumors (TGCTs), with distinct biological behaviors and clinical features 1
- Seminoma typically presents at an older median age (34 years) compared to non-seminoma (26.5 years) 2
- Non-seminoma is more likely to present with disseminated disease at diagnosis (75% of cases) compared to seminoma (only 20%) 2
- Alpha-fetoprotein (AFP) is typically elevated in non-seminoma but never in pure seminoma; elevated AFP in a supposed "seminoma" indicates mixed histology with non-seminomatous elements 1
Prognostic Classification
- The International Germ Cell Cancer Collaborative Group (IGCCCG) classifies seminoma as either good or intermediate risk, while non-seminoma can be classified as good, intermediate, or poor risk 1
- There is no poor-risk category for seminoma, reflecting its generally better prognosis 1
- 5-year survival rates for metastatic disease are 91%, 79%, and 48% for good, intermediate, and poor prognosis groups, respectively 1
Treatment Approaches for Stage I Disease
Seminoma Stage I:
- Approximately 80% of seminoma patients present with stage I disease, with a survival rate of ~99% 1
- Surveillance is the preferred strategy for stage I seminoma, with a 10-year relapse-free survival rate of 93.4% 3
- Adjuvant options include single-dose carboplatin (AUC 7) or radiotherapy (20 Gy/10 fractions), with carboplatin showing similar relapse rates but fewer long-term side effects compared to radiotherapy 1
- Relapse rate with surveillance is approximately 17%, significantly lower than for non-seminoma 4
Non-seminoma Stage I:
- Stage I non-seminoma has a higher relapse rate of approximately 29% with surveillance 4
- Risk stratification is based on lymphovascular invasion - low risk (20% relapse rate) or high risk (40-50% relapse rate) 1
- Adjuvant chemotherapy with 1-2 cycles of BEP (bleomycin, etoposide, cisplatin) is recommended for high-risk patients or those unable to comply with surveillance 1
- Retroperitoneal lymph node dissection (RPLND) plays a more significant role in non-seminoma management than in seminoma 5
Treatment of Advanced Disease
Seminoma (Stage II-III):
- Stage IIA (lymph nodes 1-2 cm): Treatment options include radiotherapy (30 Gy) or cisplatin-based chemotherapy 1
- Stage IIB/IIC: Three cycles of BEP is standard therapy 1
- Stage III: Three cycles of BEP for good prognosis; four cycles for intermediate prognosis 1
- Post-chemotherapy residual masses >3cm require FDG-PET scan evaluation; negative PET predicts absence of viable tumor with >90% accuracy 1
Non-seminoma (Stage II-III):
- Stage IIA marker-positive and IIB-III: Three cycles of BEP for good prognosis; four cycles of BEP for intermediate or poor prognosis 1
- Post-chemotherapy management requires surgical resection of all residual masses >1cm, as these may contain viable tumor or teratoma 1
- Marker decline after first cycle of chemotherapy has prognostic significance; poor decline may warrant intensification of therapy 1
Relapse Patterns and Management
- Seminoma typically relapses later (median 13 months) than non-seminoma (median 5 months) 4
- Late relapses (>2 years after treatment) occur in 2-3% of patients and are more difficult to treat, especially in non-seminoma 1
- Non-seminoma late relapses often contain yolk sac tumor (AFP-positive) or teratoma elements and respond poorly to chemotherapy 1
- Salvage treatment success rates are higher for seminoma than non-seminoma (failure rates: 12.5% vs 51.4%) 2
- Surgical resection plays a critical role in managing relapses, particularly for non-seminoma 1
Long-term Survival and Follow-up
- Stage I disease has an overall survival rate of 98.6% and cause-specific survival of 100% 4
- Patients with tunica albuginea involvement in seminoma may have higher relapse risk (10-year RFS 80% vs 94.1%) 3
- Lymphovascular invasion in non-seminoma significantly increases relapse risk (54% vs 18.7% without invasion) 3, 4
- Follow-up should focus on both relapse detection and monitoring for late treatment toxicity 1
Key Pitfalls to Avoid
- Never assume pure seminoma with elevated AFP; this indicates non-seminomatous elements 1
- Don't underestimate the importance of surgical resection of residual masses in non-seminoma, even with normal markers 1
- Avoid reducing chemotherapy doses or delaying treatment, as this may compromise cure rates 6
- Don't neglect long-term follow-up, as late relapses can occur up to 10 years after treatment, particularly in non-seminoma 2
- Remember that PET scans are valuable for evaluating residual masses in seminoma but have limited utility in non-seminoma 1