MRI is non-inferior to CT for the surveillance of stage 1 testicular seminoma. Over a 6-year period, a 3-scan schedule is non-inferior to a 7-scan schedule, regardless of imaging modality. The use of MRI instead of CT can reduce radiation exposure in this patient population . Current guidelines advocate CT surveillance following orchiectomy in patients with stage 1 testicular cancer. While this cancer has a high survival rate, there are long-term adverse health effects resulting from repeated exposure to radiation via CT scans. The phase 3 TRISST trial (NCT00589537) sought to demonstrate non-inferiority of a reduced CT schedule or MRI to safely and effectively monitor patients with stage 1 testicular cancer. Investigators randomized 669 men to 1 of 4 arms, 2 of which were monitored with CT, and 2 of which were monitored with MRI. Each imaging modality arm had 2 different frequency schedules: one scanned patients at 6, 12, 18, 24, 36, 48, and 60 months; the other scanned patients at 6, 18, and 36 months. All patients were followed for 6 years. The primary outcome measure was the proportion of patients relapsing with Royal Marsden Hospital stage ≥2C disease. Of the 669 trial participants, 82 (12%) relapsed. Only 10 of these 82 were graded as a stage ≥2C relapse. Most relapses were diagnosed at the time of scheduled imaging; additionally, relapse beyond 3 years was rare. Although there were more events in those who received 3 scans instead of 7, the criteria for non-inferiority were still met. Fewer events were observed in those who received MRI scans compared with CT. No tumor-related deaths occurred and the 5-year disease-free survival and overall survival rates were similar across all groups. Researchers asserted that surveillance is both safe and effective in stage 1 testicular seminoma, regardless of frequency or type of imaging. Furthermore, imaging beyond 3 years may actually be unnecessary, as relapse after 3 years is rare. Finally, they recommend that the standard of care should recommend MRI instead of CT, in an attempt to limit radiation exposure in this young population.
- Joffe J. Imaging modality and frequency in surveillance of stage I seminoma testicular cancer: Results from a randomized, phase III, factorial trial (TRISST). ASCO Genitourinary Cancers Symposium, 11-13 February 2021.