Malignant potential of the cryptorchid testis.

A follow-up study of 224 male patients from Rochester, Minnesota, diagnosed with cryptorchidism during the period from 1935 through 1974 was conducted to assess the frequency of subsequent testicular neoplasms. Age-specific rates for testicular neoplasm in this community were used to estimate an expected number for comparison with that observed. Two malignant testicular neoplasms have occurred in this cohort; thus, the standardized morbidity ratio was 11.4 (95% confidence interval, 1.4 to 41.1). Of the 158 patients born in the community, 11% were known to have birth weights of less than 2,500 g, approximately twice the expected occurrence. Increased risks were also noted for inguinal hernia, hypospadias, Down's syndrome, cleft lip or palate (or both), clubfoot, and congenital heart disease, for which the standardized morbidity ratios were 3.6, 4.7, 17.8, 11.3, 11.7, and 2.7, respectively. The increased risk for malignant neoplasms observed in this cohort of patients with cryptorchidism is consistent with that found in earlier studies.