medwireNews: Minimizing irradiation by either switching from computed tomography (CT) to magnetic resonance imaging (MRI) scans or by reducing scan frequency is not detrimental to stage I seminoma outcomes, show data from the UK-based TRISST trial.
Writing in the Journal of Clinical Oncology, Fay Cafferty (MRC Clinical Trials Unit at UCL, London) and co-authors say that “surveillance is a safe management approach for stage I seminoma—advanced relapse was rare, salvage treatment successful, and long-term outcomes excellent, regardless of imaging frequency or modality.”
The multicenter phase 3 trial included 669 participants who had undergone orchiectomy for stage I seminoma in 2008–2014 with no adjuvant therapy planned. They were randomly assigned to receive either seven follow-up CT scans (at 6, 12, 18, 24, 36, 48, and 60 months), seven follow-up MRI scans (same schedule), three CT scans (6, 18, and 36 months), or three MRI scans (same schedule).
After a median 6 years of follow-up, the overall relapse rate was 12% and the researchers report that detection of relapse at an advanced stage (≥IIC) was rare, with just 10 (1.5%) events recorded.
The trial met its primary outcome of noninferiority, aiming to exclude absolute increases of 5.7% or more in stage IIC or higher relapse, between MRI and CT and also with three scans versus seven.
Specifically, the advanced relapse rate was 0.6% with MRI and 2.6% with CT, corresponding to an absolute reduction of 1.9% with MRI.
In addition, 2.8% of participants who received three scans (either MRI or CT) relapsed compared with 0.3% of those who received seven scans, corresponding to a 2.5% absolute increase.
When the four trial arms were considered separately, the researchers found that the difference in 6-year relapse incidence was greater between the three CT and seven CT arms (5.1% vs 0.0%) than between the three and seven MRI arms (0.6% in both groups).
And the team observed similar results when they defined advanced relapse as a tumor of 3 cm or larger.
Among the patients who relapsed, there were no tumor-related deaths and the 5-year overall survival rate approached 100% in all groups, indicating that “[r]elapse treatment was successful,” Cafferty et al remark.
The authors conclude: “In this young patient group who are very unlikely to die from their seminoma cancer, minimizing exposure to potentially harmful radiation is important.
“TRISST demonstrates that the intensity and duration of CT surveillance can be reduced, or MRI can be used, to reduce irradiation, and that long-term outcomes remain excellent.”
medwireNews is an independent medical news service provided by Springer Healthcare Ltd. © 2022 Springer Healthcare Ltd, part of the Springer Nature Group
J Clin Oncol 2022; doi:10. 1200/JCO.21.01199