Stage I Seminoma: Post-Orchiectomy MRI Surveillance Noninferior to CT

CT image of seminoma.

For patients with stage I seminoma, a germ cell tumor of the testicle or other extragonadal locations, post-orchiectomy surveillance with magnetic resonance imaging (MRI) is noninferior to computed tomography (CT) imaging and avoids excess radiation, according to results of the phase 3 Trial of Imaging and Surveillance in Seminoma Testis (TRISST) presented this past weekend at the American Society of Clinical Oncology (ASCO) Genitourinary Cancers Symposium.

“Survival after orchiectomy in stage I seminoma is almost 100%,” write the study investigators, led by first author Johnathan K. Joffe, MD, FRCP, MacMillan Consultant in Medical Oncology at Huddersfield Royal Infirmary in West Yorkshire, the United Kingdom. “Computed tomography surveillance is an international standard of care and avoids adjuvant therapy. In this young population, who are unlikely to die from testicular cancer, minimizing irradiation is vital.”

Dr. Joffe and colleagues investigated whether CT scans can be reduced or replaced with MRIs to avoid excess radiation while minimizing advanced relapses in patients with stage I seminoma. The trial enrolled 669 patients who had undergone orchiectomy, a surgical procedure to remove one or both testicles, and who were not scheduled to receive adjuvant therapy. Patients were randomized to receive either three or seven CT scans or three or seven MRIs. The primary end point was six-year incidence of stage ≥IIC relapse per the Royal Marsden Hospital (RMH) staging classification, with a goal of excluding a 5.7% or greater increase of relapse with MRI versus CT imaging. Secondary end points included the incidence of relapse greater than 3 cm, disease-free survival, and overall survival.

At a median follow-up of 72 months, 12% of patients had relapsed, with only 10 patients (1.5%) experiencing stage ≥IIC relapse across all groups. Patients who received seven scans, either MRI or CT, had a lower risk of relapse compared with those who received three scans (0.3% vs 2.8%). Of the relapses occurring in the three-scan group, 44% could potentially have been identified earlier if the patients had received seven scans. Fewer relapses occurred in patients receiving MRI compared with CT (0.6% vs 2.5%). Across all groups, the majority of relapses were detected on scheduled imaging, with less than 1% occurring after three years. Complete responses were experienced by 81% of patients, and no tumor-related deaths occurred. Five-year median disease-free survival and overall survival were 87% and 99%, respectively.

“Surveillance is a safe management approach in stage I seminoma—advanced relapse is rare, salvage treatment successful, and long-term outcomes excellent, regardless of imaging frequency or modality,” conclude Dr. Joffe and colleagues in their presentation abstract. “Relapse beyond three years is rare and imaging may be unnecessary. MRI is noninferior to CT, avoids irradiation, and should be recommended.”

For More Information

Joffe JK, Cafferty FH, Murphy L, et al (2021). Imaging modality and frequency in surveillance of stage I seminoma testicular cancer: results from a randomized, phase III, factorial trial (TRISST). J Clin Oncol (Genitourinary Cancers Symposium Abstracts), 39(suppl_6). Abstract 374. DOI:10.1200/JCO.2021.39.6_suppl.374

Image credit: Jmarchn. Licensed under CC BY-SA 3.0

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