{'fraction_non_alphanumeric': 0.024466750313676285, 'fraction_numerical': 0.020075282308657464, 'mean_word_length': 4.885608856088561, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Medical Research Council prospective study of surveillance for stage I testicular teratoma. Medical Research Council Testicular Tumors Working Party.

PURPOSE
A prospective study of surveillance after orchidectomy alone in patients with stage I nonseminomatous germ cell testicular tumor (NSGCT) was performed to determine the relapse-free rate and to identify the histologic criteria that predict for relapse.


PATIENTS AND METHODS
Three hundred ninety-six patients from 16 United Kingdom and one Norwegian centers were entered onto the study between January 1, 1984 and October 1, 1987 of whom 373 were eligible for analysis. In a previous retrospective study, we defined a prognostic index based on histologic criteria that identified a group of patients with a high risk of relapse. This index was based on the presence of venous and lymphatic invasion, undifferentiated cells, and the absence of yolk sac elements in the primary tumor.


RESULTS
The 2-year actuarial relapse-free rate after orchidectomy was 75% (95% confidence interval, 71% to 79%), and the rate at 5 years was 73%. Five patients died of tumor or treatment-related complications, which resulted in a 5-year survival of 98%. The relapse-free rate in patients with three or four risk factors was 54%.


CONCLUSIONS
This study confirms the safety of surveillance as a method of management and identifies a group of patients with a high risk of relapse. A prospective phase II study has been initiated to determine whether two courses of platinum-based adjuvant chemotherapy will prevent relapse in these high-risk patients.