Is radiotherapy still an option for residual retroperitoneal masses in stage IIC seminoma?

In patients with clinical stage IIC seminoma, residual retroperitoneal masses are detected in up to 80% of patients after chemotherapy. Lesions < 3 cm are generally monitored; however, the management of patients with residuals > 3 cm remains a matter of debate. Herein, we present a case series of these patients who underwent radiotherapy (RT) and discuss the role of RT in these cases.

Three patients with de novo and two patients with relapsed stage IIC seminoma who underwent RT for retroperitoneal residual masses after chemotherapy at two centers between 2014 and 2025 were retrospectively evaluated. All treatment decisions were made by a multidisciplinary board.

The median age of the patients was 43 (26-47) years, and the median follow-up was 30 (10-120) months. Following radical orchiectomy, all patients received 3-4 cycles of BEP chemotherapy. The median size of the post-chemotherapy residual was 6.5 (3.2-8.5) cm. PET-CT was positive with SUVmax > 3 for all patients. Two patients received only paraaortic RT, three patients received paraaortic + ipsilateral pelvic lymph node RT with a total dose of 25.5 Gy. An additional dose of 10 Gy was prescribed to the residual mass. All treatments were implemented with intensity-modulated radiotherapy (IMRT). Three patients experienced grade 1 nausea. No recurrence or secondary malignancy was detected at final follow-up.

Radiotherapy may be considered as a potential non-invasive option for managing residual retroperitoneal masses after chemotherapy in stage IIC seminoma, particularly in patients with a high risk of recurrence and in whom retroperitoneal lymph node dissection (RPLND) is anticipated to be associated with morbidity.