Why the grass isn't always greener.

Using data from the Hospital In-patient Enquiry (HIPE) Coggon and Nelms (1984) reported a substantial increase in operations for torsion of the testis between 1968 and 1980. The cumulative discharge rate (for ages 0 to 34) increased 2.3-fold from 0.35% in 1968 to 0.82% in 1980. A subsequent investigation of cases in the Wessex Health Region by these authors confirmed this increase and could find no artefactal explanation for it (Nelms & Coggon, 1986). Undescended testis has also been increasing in incidence over this period (Chilvers et ail., 1984; John Radcliffe Hospital Cryptorchidism Study Group, 1986) and, since torsion has been reported as being associated with an anatomical abnormality (Scorer & Farrington, 1971), a common aetiological factor may be responsible for the increase in both conditions (Coggon & Nelms, 1984). Undescended testis is the major known risk factor for testicular cancer not only in the undescended testis itself (whether or not brought down by orchidopexy) but also for the contralateral scrotal testis (Henderson et al., 1983; Pike et al., 1986). This suggests that it is not the position of the testis that is important but that some underlying factor predisposes to both conditions. If there is a common aetiological factor in cryptorchidism and torsion, it is reasonable to suggest that patients with a history of torsion of the testis might also be at increased risk of developing cancer of the testis. We have investigated this possibility using data from the Royal Marsden Hospital (RMH). The records of all 871 patients who attended the RMH for the first time with a diagnosis of testicular cancer between January 1, 1975, and December 31, 1984, were reviewed. Seven hundred and twenty four of these patients were born in the UK and were resident in the UK at the time of diagnosis; it is only for these patients that the expected number of testicular torsions can be calculated for comparison purposes using HIPE data. Almost all patients had had their orchidopexy elsewhere and were referred soon afterwards for detailed evaluation and, if necessary, further treatment. Patients with bilateral tumours were included only if they attended the RMH with their first tumour within this period. Only patients with germ-cell tumours were eligible; patients with lymphomas and sarcomas were excluded, as were patients whose tumour was not positively identified as being a testicular primary. The case-notes of the patients were abstracted by one of two research nurses onto a standard form. The information abstracted included details of the histology of the tumour, history of undescended testis, torsion and other testicular problcms. Tumours were classified as seminomas (pure seminoma with no other elements present) or teratomas (all others). We calculated age-specific rates for operations for testicular torsion for each calendar year from 1968 to 1980 using the HIPE data (see Figure 1). Assuming that the 1968 rates applied to all previous years and the 1980 rates to all