Imaging modality and frequency in surveillance of stage I seminoma testicular cancer: Results from a randomised, phase III, non-inferiority trial (TRISST)


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Johnathan Joffe1, Fay Cafferty2, Laura Murphy2, Gordon Rustin3, Aslam Sohaib4, Rhian Gabe5, Sally Stenning2, Elizabeth James2, Dipa Noor2, Simona Wade2, Francesca Schiavone2, Sarah Swift6, Elaine Dunwoodie6, Marcia Hall3, Anand Sharma3, Jeremy Braybrooke7, Jonathan Shamash8, John Logue9, Henry Taylor2, Ivo Hennig10, Jeff White11, Sarah Rudman12, Jane Worlding13, Richard Kaplan2, Robert Huddart4
1Calderdale and Huddersfield NHS Foundation Trust, 2Other, 3Mount Vernon Cancer Centre, 4Institute of Cancer Research (ICR), 5Queen Mary University of London, 6St James’s Hospital, 7University Hospitals Bristol NHS Foundation Trust, 8Barts Cancer Institute, 9The Christie NHS Foundation Trust, 10Nottingham University Hospitals NHS Trust, 11Beatson West of Scotland Cancer Centre, 12Guy’s and St Thomas’ NHS Foundation Trust, 13University Hospitals Coventry and Warwickshire NHS Trust

Abstract

Background

Survival in stage I seminoma is almost 100%. CT surveillance is an international standard of care, avoiding adjuvant therapy. In this young population, minimising irradiation is vital. The TRrial of Imaging and Surveillance in Seminoma Testis (TRISST) assessed whether MRIs or a reduced CT schedule could be used without an unacceptable increase in advanced relapses.

Method

TRISST was a phase III, non-inferiority, factorial trial. Eligible men had undergone orchiectomy for stage I seminoma with no adjuvant therapy planned. Randomisation was to: 7 CTs (6, 12, 18, 24, 36, 48, 60 months); 7 MRIs (same schedule); 3 CTs (6, 18, 36 months); or 3 MRIs. The primary outcome was 6-year incidence of RMH stage ≥IIC relapse (>5cm), aiming to exclude increases ≥5.7% (from 5.7% to 11.4%) with MRI (vs CT) or 3 scans (vs 7); target n=660, all contributing to both comparisons. Secondary outcomes included relapse ≥3cm, disease-free and overall survival. Both intention-to-treat and per protocol analyses were performed.

Results

669 patients enrolled (35 UK centres, 2008-2014); mean tumour size 2.9cm, 358 (54%) low risk (<4cm, no rete testis invasion). With median follow-up 72 months, 82 (12%) relapsed. Stage ≥IIC relapse was rare (10 events).  Though statistically non-inferior, more events occurred with 3 scans (9, 2.8%) vs 7 scans (1, 0.3%): 2.5% absolute increase, 90% CI (1.0%, 4.1%). Only 4/9 could have potentially been detected earlier with 7 scans. Non-inferiority of MRI vs CT was also shown; fewer events occurred with MRI (2, 0.6% vs 8, 2.5%), 1.9% decrease (-3.5%, -0.3%). Per protocol analyses confirmed non-inferiority for both comparisons. 5-year survival was 99%, similar across arms, with no tumour-related deaths.

Conclusion

Surveillance is a safe management approach – advanced relapse is rare, salvage treatment successful, and outcomes excellent, regardless of imaging frequency or modality. MRIs or a reduced CT schedule can be recommended to reduce irradiation.

Impact statement

As the largest trial in stage I seminoma, TRISST has demonstrated that patients undergoing surveillance can be effectively monitored with MRI or with fewer CT scans than currently used, with the potential to avoid harmful irradiation in this young patient group.