Strategies for retroperitoneal lymph node dissections (RPLND) in metastatic testicular seminoma were a key topic at the 2024 Society of Urologic Oncology (SUO) annual meeting. Dr. Timothy Masterson discussed how management of testicular seminoma is evolving, influenced by historical data and recent trials evaluating RPLND as an alternative to radiotherapy and chemotherapy to mitigate long-term risks like secondary malignancies and cardiovascular morbidity.
Historical Context and Shifting Paradigms
Early studies from the mid-20th century established orchiectomy followed by radiotherapy as a standard, citing high cure rates. However, the recognition of long-term toxicities associated with both chemotherapy and radiotherapy has spurred interest in alternative treatment approaches, particularly RPLND, for suitable patients.
RPLND as a Primary Treatment Option
Following the SEMS, PRIMETEST, and COTRIMS trials, international guidelines now acknowledge RPLND as an appropriate treatment for stage IIA or IIB seminoma with lymph nodes ≤3 cm, especially for patients wishing to avoid chemotherapy or radiotherapy's long-term effects.
Mapping Studies and Modified Templates
Mapping studies in non-seminomatous germ cell tumors have refined RPLND techniques, leading to modified templates that:
- Eliminate suprahilar dissection except in bulky disease.
- Emphasize resection of the ipsilateral gonadal vessels.
- Recognize that contralateral iliac/interiliac regions are rarely involved.
- Define the risk of cross-over to contralateral basins in advancing disease.
- Highlight the negative impact on fertility with bilateral templates.
Weissbach et al.'s mapping study demonstrated that solitary nodes of the right testis tumor were located with decreasing frequency in the upper and lower interaortocaval, lower paracaval and precaval, upper precaval and right common iliac, upper paracaval and upper preaortic zones. Primary deposits of the left testis tumor were seen predominantly in the upper para-aortic zone. Follow-up prospective trials with modified templates have shown that 95–97% of metastatic deposits are confined to the ipsilateral area. In-field relapses after a primary RPLND are rare, with aggregate estimates of 1.6% reported in the literature.
University of Indiana Experience
The University of Indiana published its experience with primary RPLND for non-seminomatous germ cell tumors in 2020, analyzing oncologic outcomes in 274 patients. The majority (78%) presented with clinical stage I disease. Modified unilateral templates were performed in 94% of patients. After a median follow-up of 55 months, only 12% experienced disease recurrence. Of the 113 patients with pathological stage (PS)-II disease who did not receive chemotherapy, 19% had disease relapse, indicating that 81% were cured with surgery alone. Contralateral recurrences were observed in only 1.6%. The study concluded that modified unilateral template dissection provided excellent oncologic control while minimizing morbidity.
Contemporary Surgical Experience and Trial Data
Three major trials—SEMS, PRIMETEST, and COTRIMS—have evaluated primary RPLND for stage IIA/B seminomas. Key differences between the trials included varying inclusion criteria based on tumor size and the extent of disease. Survival outcomes were generally similar across the trials, with COTRIMS showing the best 2-year recurrence-free survival rates (89% versus 70% and 81% in PRIMETEST and SEMS, respectively). All trials reported a 2-year overall survival of 100%. The pN0 rate ranged from 9% to 16%, suggesting the need for improved preoperative identification of patients without residual viable disease.
Relapse patterns varied, with in-field relapses observed in 9% of SEMS and PRIMETEST patients, respectively, and contralateral relapses in 5% and 12%, respectively. Notably, no COTRIMS patients experienced in-field or contralateral relapse. A single-center experience from Indiana University, including 67 patients undergoing primary RPLND for retroperitoneal-limited seminoma, reported a 2-year recurrence-free survival of 80.2% for RPLND-only patients without adjuvant chemotherapy. One patient had an infield recurrence, and two had contralateral recurrences.
Unilateral vs. Bilateral Template Approaches
Analysis from the University of Indiana cohort suggests that recurrences are significantly higher with a unilateral template (25% versus 15%), both in-field (6% versus 0%) and contralaterally (17% versus 13%). For the 31 patients undergoing bilateral template dissection, six (19.4%) had contralateral disease on final RPLND pathology, with four having disease noted on preoperative CT scans.
Technical Considerations
Minimizing in-field recurrence risk involves careful tissue handling, especially in patients with extranodal extension. Perioperative outcomes for CS IIA/B seminoma patients undergoing primary RPLND are generally favorable, with median lengths of stay ≤3 days and mostly preserved ejaculatory function.
Key Takeaways
Dr. Masterson concluded that recurrence-free survival with primary RPLND for stage IIA/B seminomas is 80-90%. Higher rates of contralateral disease/crossover (13-16%) and a greater risk of pelvic/inter-iliac disease/relapse (~4-10%) were noted. Improved survival outcomes appear to be associated with full left or bilateral templates, time to relapse >12 months, and earlier stage disease.
