Testicular cancer in fire fighters: a cluster investigation

To investigate an apparent cluster of four testicular cancer cases in Wellington fire fighters with a view to determining whether there was a common causal factor, and whether the cluster was indicative of an occupational risk for fire fighters generally.

Subjects were interviewed about possible risk factors and occupational histories using a structured questionnaire; medical records were reviewed, and diagnoses were verified from the original histological slides. Data on testicular cancer in fire fighters were obtained from the New Zealand cancer registry. Standardised incidence ratios were calculated to assess the likelihood that the cluster had arisen by chance.

All four cancers were verified as germ cell testicular cancers. No common risk factors were apparent from the review of the medical records or from the questionnaire interviews. The only testicular cancers known to have occurred in Wellington fire fighters in the 1980s were the four investigated in this study. Only two of the four cases investigated were registered with the New Zealand cancer registry. The relative risk estimate for Wellington fire fighters for the period 1980-91 was 8.2, with an approximate 95% confidence interval of 2.2-21 (p = 0.002).

There was an unusually high risk of testicular cancer in Wellington fire fighters in the 1980s, with no obvious explanations, although chance could not be excluded. Whether this high risk continues in the 1990s would require a separate investigation. At present the weight of evidence does not indicate that fire fighters in other areas of New Zealand also experienced an elevated testicular cancer incidence rate.