ASCO GU 2018: Effect of Number of CT Scans During Follow-Up of Patients with Clinical Stage I Seminoma: A Trial-Level Meta-Analysis

San Francisco, CA ( Dr. Patrizia Giannatempo presented results of her team’s trial level-analysis assessing the effect of number of CT scans during follow-up of patients with clinical stage I (CSI) seminoma. Despite the overall high cure-rate for patients with CSI seminoma regardless of the intervention used, huge discrepancy exists in the number of CT scans that are proposed to patients during the follow-up period, mainly during active surveillance. The objective of this study was to assess the impact of such a discrepancy in diagnosing patients with a high-risk relapse using published literature and a meta-analysis.

The authors searched for arms of studies of active surveillance or active treatment (either chemotherapy or radiotherapy) in patients with CSI seminoma. Meta-analytic techniques were used to pool and compare study level data of active surveillance and active treatment groups and to study the impact of the number of CT scans (as a continuous variable) during follow-up upon the percentage of patients with CSIII or with IGCCCG intermediate prognosis seminoma at relapse.

There were 22 studies analyzed (33 arms, n = 11,025 pts) of which 39.6% had a high-risk seminoma. Among these patients, 38.8% (n = 4,274) underwent active surveillance vs 61.2% (n = 6,751) active treatment. The number of CT scans ≤2 years ranged from 4-8 and 0-7 for AS and AT groups, respectively. Overall, 922 patients experienced a relapse (651 in active surveillance and 271 in active treatment arms), 73.9% <2 years and 22.3% at 2-5 years follow-up. Statistical modeling showed that the estimated rates of CSIII relapse (6% in active surveillance, 32% in active treatment groups, p = 0.0068) and intermediate prognosis relapse (2% in active surveillance, 11% in active treatment group, p = 0.0051), were divergent for the two groups. A higher number of CT scans in the first 2 years of follow-up tended to reduce the occurrence rate of both endpoints, but failed to reach statistical significance in active surveillance (p = 0.334 for CSIII, unidentifiable for intermediate prognosis relapse), as well as in active treatment (p = 0.438, p = 0.103). The number of CT scans in 3-5 years follow-up had an even weaker prognostic effect. 

The authors summarized that in this trial-level meta-analysis, there was no statistically-significant association between the number of CT scans performed during follow-up of CSI seminoma patients and the diagnosis of high-risk relapses. A large discrepancy in the total number of CT scans was generally found between arms. In contrast, as expected, the pattern of relapse of CSI seminoma was different according to the treatment group. Based on these results, and the continued movement towards reducing the harm of radiation exposure, there is room for reducing the number of CT scans during follow-up of CSI seminoma patients undergoing active surveillance.

Presented by: Patrizia Giannatempo, MD Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy

Co-Authors: Daniele Raggi, Elena Tagliabue, Mario Catanzaro, Davide Biasoni, Tullio Torelli, Silvia Stagni, Nicola Nicolai, Luigi Piva, Roberto Salvioni, Luigi Mariani, Andrea Necchi; Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy

Written by: Zachary Klaassen, MD, Urologic Oncology Fellow, University of Toronto, Princess Margaret Cancer Centre, @zklaassen_md at the 2018 American Society of Clinical Oncology Genitourinary (ASCO GU) Cancers Symposium, February 8-10, 2018 - San Francisco, CA