Comparison of Imaging Regimens for Stage I Seminoma After Orchiectomy
Men who have had treatment for early-stage testicular cancer may benefit from fewer monitoring scans, freeing them from some of the harmful radiation that comes from computerized tomography (CT) imaging, according to results from the phase III TRISST clinical trial presented by Joffe et al at the 2021 Genitourinary Cancers Symposium (Abstract 374).
The study also found that using magnetic resonance imaging (MRI) was noninferior to CT scans in terms of detecting relapse. Using fewer CT scans, or using MRI instead, could expose men to less harmful radiation.
Currently, men with stage I testicular seminoma (which accounts for 40% to 50% of cases) have surgery to remove the affected testicle and are monitored for relapse by having regular CT scans for 5 years. While essential, having a CT scan exposes men to some radiation, which may slightly increase their risk of developing other cancers later on.
Researchers sought to find if men can have CT scans less often, or have MRI scans instead, without seeing an unacceptable increase in cases where the cancer is only detected in an advanced stage.
TRISST Study Methods and Findings
The TRISST trial was led by researchers from The Institute of Cancer Research, London, Leeds/Huddersfield, and University College London. The study enrolled 669 men with stage I testicular cancer who had had undergone orchiectomy. Men were monitored either using the standard seven CT scans, three CT scans, or the same schedules but using MRI scans.
Results showed that 82 (12%) of the men experienced a cancer relapse, but only a small proportion—10 patients—had advanced stage disease at detection. The majority of relapses happened within 3 years (in all but 5 of the men), suggesting that scanning beyond 3 years may be unnecessary.
When comparing the numbers of relapses that were detected at advanced stage, nine (2.8%) were found in the three-scan group compared with one (0.3%) in the seven-scan group. While this shows that some of the more advanced-stage relapses could have been detected earlier if given seven scans rather than three, all men who relapsed were treated successfully.
When comparing the two types of scans, more advanced-stage relapses were detected with CT (8; 2.5%) compared with MRI (2; 0.6%), but the difference was not significant, and all men in both trial arms were treated successfully.
Avoiding Unnecessary Radiation Exposure
Robert Huddart, PhD
Robert Huddart, PhD, Professor of Urological Cancer at The Institute of Cancer Research, London, and Consultant in Urological Oncology at The Royal Marsden NHS Foundation Trust, one of the lead authors of the study, said, “When looking at a young population of men who are unlikely to die from testicular cancer, avoiding unnecessary radiation exposure is vital.”
“We found that the benefit of having continued CT scans beyond 3 years was outweighed by the potentially harmful exposure to radiation, given the small number of men who relapse and our success at treating those patients,” he continued. “Our study also found that MRI could have real benefits for men with testicular cancer in achieving similar outcomes to CT but with lower doses of radiation. Reducing the number of scans men have could help alleviate the anxiety that some patients experience…We are now collecting health economic data to see if using three MRI scans could be recommended as the standard surveillance plan.”
Disclosure: For full disclosures of the study authors, visit coi.asco.org.The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.