Peroneal nerve neuropathy in cancer patients: a paraneoplastic syndrome?

To investigate the occurrence of symptomatic peroneal neuropathy (PN) in cancer patients, as well as that of cancer in PN patients and to seek possible factors in the aetiology of PN.

Clinical, neurographical, and myographical data of patients with PN, in two general neurology clinics during a 5-year period (1988-1992) were analysed retrospectively. A population-based cancer registry was consulted for epidemiological data in the area.

The catchment population of the two clinics consisted of 433,142 people, and 8,766 new cancer patients were diagnosed. PN was diagnosed in 372 patients, of whom 74 suffered from cancer (in 56 PN was believed to be related to cancer). The crude relative risk of PN in patients with cancer compared with patients without cancer was 8.6. After correction for differences in age and sex between the compared groups, the relative risk dropped to 3.4 (2.8 for women and 3.6 for men). The crude relative risk of cancer for patients with PN relative to people without PN was 7.5. The relative risk, after correction for age and sex, was 2.8 (2.5 for women and 2.9 for men). All relative risks were significant (P < 0.001), but did not differ between the sexes (P > 0.4). Weight loss was established in 35/56 patients, but in 17/56 it was unknown. PN has not been found to be part of a polyneuropathy. Chemotherapy did not play a causal part. In some patients PN preceded the diagnosis of cancer.

The occurrence of PN seems to be higher in patients with cancer than in people without cancer. Cancer was found in patients with PN more often, particularly in elderly men, than would be expected from the occurrence in the total population. PN in patients with cancer is supposed to be due to a combination of metabolic and mechanical factors. The findings justify a prospective study of the relation between PN and cancer.