The prognostic significance of the tumour infiltrating lymphocyte count in stage I testicular seminoma managed by surveillance

The degree of lymphocytic infiltration is a significant determinant of outcome for a variety of malignancies, but its role in seminoma is unknown. 150 men with stage I testicular seminoma presenting between 1981 and 1993 were managed by surveillance following orchidectomy. The presence of tumour infiltrating lymphocytes (TILs) in each case was classified as high, intermediate or low. At a median follow-up of 9.4 years, 30 of the 150 men developed recurrent seminoma. On univariate analysis, the risk of relapse was associated with age ⩽33 years (P=0.002), tumour diameter >6 cm (P=0.03), lymphatic or vascular invasion (P=0.04), tumour invasion of rete testis (P=0.05), and lower TIL count (P=0.02). On multivariate analysis, statistically significant predictors of risk of relapse were age ⩽33 years (hazard ratio (HR) 4.6 (95% confidence intervals (CI): 1.7–12.2)) and tumour diameter >6 cm (HR 2.8 (CI: 1.2–6.5)). Lower TIL count was of borderline statistical significance (HR 1.8 (CI: 0.96–3.44)). The functional role of the lymphocytic infiltrate in testicular seminoma warrants further study.