Abstract 714P
Background
Outcomes in stage I seminoma are excellent. 15% relapse when managed with surveillance and survival approaches 100%. Risk stratification would allow management to be tailored, avoiding unnecessary treatment and/or irradiation. However, validated factors based on contemporary data are lacking. The Trial of Imaging and Surveillance in Seminoma Testis (TRISST, ISRCTN65987321) - the largest in this setting - investigated optimal frequency and modality of imaging. Here, trial data are used to determine prognostic factors for relapse.
Methods
Eligible men had undergone orchiectomy for stage I seminoma, had normal post-op AFP and β-HCG (AFP not known to be raised pre-op) and no adjuvant therapy planned. Primary analysis demonstrated non-inferiority of MRI vs CT and 3 vs 7 surveillance scans over 5 years. Multivariate models to predict relapse considered: age, mass size, rete testis invasion, T stage, vascular/lymphatic invasion, tumour side, raised markers (pre-op β-HCG, LDH, post-op LDH). Cox proportional hazards models were used to construct hazard ratios and confidence intervals. Backwards model selection was applied; p>0.05 determined exclusion from the model.
Results
669 men were randomised (2008-2014). Mean age 39; median tumour size 2.5cm; 221 (33%) had rete testis invasion; 581 (87%) T1, 72 (11%) T2, 16 (2%) T3; 82 (13%) had vascular or lymphatic invasion; 324 (48%) left-sided. Pre-op β-HCG and LDH and post-op LDH were raised for 87 (14%), 124 (22%) and 58 (9%) respectively. 82 (12%) relapsed after median 6 years. Age, tumour size and T stage were prognostic; rete testis invasion was not. Highest risk was associated with T3 disease and ≥4cm; risk was also increased for those <30 years and 2-4cm masses. Table: 714P
| Total Patients | Relapses | HR | 95% Confidence interval | |
| Age | ||||
| <30 | 159 | 31 | 1 | |
| 31-40 | 220 | 23 | 0.49 | 0.283, 0.838 |
| 40+ | 290 | 28 | 0.43 | 0.255, 0.713 |
| Tumour size | ||||
| <2cm | 202 | 11 | 1 | |
| 2-3cm | 173 | 21 | 2.3 | 1.106, 4.765 |
| 3-4cm | 142 | 19 | 2.47 | 1.172, 5.228 |
| ≥4cm | 152 | 31 | 4.0 | 1.995, 8.011 |
| T stage | ||||
| T1 | 581 | 62 | 1 | |
| T2 | 72 | 13 | 1.46 | 0.809, 2.711 |
| T3 | 16 | 7 | 3.89 | 1.768, 8.574 |
Conclusions
Data confirm tumour size (≥4cm) is prognostic for relapse in stage I seminoma and suggest increased risk with younger age and higher T stage. These factors might be used to tailor management approach.
Clinical trial identification
ISRCTN65987321; NCT00589537.
Editorial acknowledgement
Legal entity responsible for the study
University College London.
Funding
Cancer Research UK.
Disclosure
R.A. Huddart: Financial Interests, Personal and Institutional, Stocks/Shares: Cancer Centre London; Financial Interests, Personal and Institutional, Advisory Role: Roche; Financial Interests, Personal and Institutional, Advisory Role: MSD; Financial Interests, Personal and Institutional, Advisory Role: Astellas; Financial Interests, Personal and Institutional, Advisory Role: Nektar; Financial Interests, Personal and Institutional, Advisory Role: Janssen; Financial Interests, Personal and Institutional, Speaker’s Bureau: Janssen; Financial Interests, Personal and Institutional, Speaker’s Bureau: Roche; Financial Interests, Personal and Institutional, Research Grant: Roche; Financial Interests, Personal and Institutional, Research Grant: MSD; Financial Interests, Personal and Institutional, Research Grant: Nektar; Financial Interests, Personal and Institutional, Research Grant: Janssen; Financial Interests, Personal and Institutional, Research Grant: Bristol Myers Squibb. G.J. Rustin: Financial Interests, Personal and Institutional, Advisory Board: AbbVie; Financial Interests, Personal and Institutional, Expert Testimony: Fukirebio America Inc. All other authors have declared no conflicts of interest.