Decrease in radiation therapy rates in patients with stage I seminoma: a population-based study

Radiotherapy has long been considered the standard adjuvant treatment after radical orchidectomy for stage I seminoma. However, active surveillance and carboplatin chemotherapy have recently become alternative strategies. Despite this, the transition in management regimens is not yet fully recognized. Thus, this study aimed to analyze the 40-year trend in radiotherapy for patients with stage I seminoma in the United States.

We identified 21,976 men in the Surveillance, Epidemiology, and End Results (SEER) database who were registered in 18 centers and who had a diagnosis of localized testis seminoma between 1975 and 2015. Patients of unknown age or whose tumors were not malignant were excluded. We investigated the rate of radiotherapy, chemotherapy and surveillance by year of diagnosis, clarified the characteristics related to the decline in radiotherapy rate, and analyzed patient survival by year of diagnosis.

From 1975 to 2015, 52.9% (11,622/21,976) patients with stage I seminoma received external radiotherapy. The rate of radiotherapy, however, gradually decreased to 46.7% (189/405) in 2008, 18.6% (70/376) in 2012, and 5.3% (19/359) in 2015. Patients aged under 34 years and married patients were more likely to avoid radiotherapy in the 21^st century. Compared with the 1975-1999 time period, patient overall survival (OS) decreased significantly in 2000-2007. However, OS during 2008-2015 was not statistically different than that during the 1975-1999 time period.

The role of radiotherapy in patients with stage I seminoma has fundamentally changed in the past 40 years and is no longer an essential treatment in the real-world management of this patient group.