Introduction

The baseline risk of relapse following orchiectomy is approximately 15% in patients with clinical stage I (CSI) seminoma and 30% in patients with CSI non-seminoma (NSGCT). Surveillance has been widely adopted for initial management. However, the baseline relapse risk does not reflect how prognosis may change the longer a patient has survived without relapse. This dynamic relapse risk is referred to as conditional risk of relapse and can provide important prognostic information for physicians and patients.

Methods

We performed a retrospective review of patients managed with surveillance for CSI testicular cancer in Denmark and the Princess Margaret Cancer Center, Toronto, Canada, between 1980 and 2014. Conditional risk of relapse was estimated using the Kaplan-Meier method. We stratified patients based on validated risk factors for relapse. We used linear regression to determine trends of conditional risk over time.

Results

We identified 3,601 patients of which 2,462 (68.6%) had seminoma and 1,139 (31.6%) had NSGCT. Median follow-up in those without relapse was 12.1 (interquartile range 8.0 to 19.5) years and 9.4 (interquartile range 5.1 to 17.1) years in seminoma and NSGCT, respectively. At orchiectomy, the baseline risk of relapse at 5 years was 53.2%, 22.1%, 21.2%, and 12.4% in patients with high-risk NSGCT (CSIB with pure embryonal carcinoma), low-risk NSGCT (CSIA without pure embryonal carcinoma), seminoma with tumour size ≥ 3cm, and seminoma with tumour size less than 3cm, respectively. The conditional relapse risk decreased over time in all groups (p<0.001), but did so at different rates (Figures 1 and 2). For patients without relapse at 3 years, the corresponding risk of relapse within the next 5 years was 6.6%, 0.9%, 3.5%, and 2.0%, respectively (Figures 1 and 2).

Conclusions

Our pooled study is the largest to date to provide conditional risk of relapse for patients with CSI testicular cancer on surveillance. These results can be used to provide patients with prognostic information and tailor surveillance protocols to reduce the intensity of follow-up in patients with a low risk of future relapse.

Funding

none