Outcome of peroneal neuropathies in patients with systemic malignant disease

Abstract

Rubin et al. recently published an article in Cancer on the relation between peroneal neuropathy and systemic malignant disease.1 We would like to present some comments and additional data, based on our own experience,2 that were not referred to in their article. Our point of departure was a retrospective review of patients presenting with peroneal neuropathy. Peroneal neuropathy was diagnosed in 372 persons within a 5-year period (1988–1992) at 2 general neurology clinics. Seventy-four of these patients also had cancer. In 56 cases, the cancer was believed to be associated with the peroneal neuropathy, as based on temporal relation and progression of the tumor. As both clinics are situated in a relatively isolated area of The Netherlands (between Belgium and Germany), where there is hardly any outflow to other clinics, epidemiologic data could be used to obtain relative risks. The catchment population of the clinics consisted of 433,142 people, and 8766 new cancer patients were diagnosed. The relative risk, corrected for age and gender, for peroneal neuropathy in cancer patients compared with patients without cancer was 3.4. The relative risk of cancer for patients with peroneal neuropathy compared with people without peroneal neuropathy was 2.8. Cancer was found particularly more often in elderly men who had peroneal neuropathy. Rubin et al. found 58 patients (0.05%) with peroneal neuropathy among 115,081 patients with systemic malignant disease. We found 56 (0.64%) among 8766 cancer patients. Part of this difference may be explained by the selection criteria Rubin et al. applied. Lung carcinoma was the most frequently occurring tumor in our group (22/56), followed by digestive tract (10/56), urogenital tract (9/56), and hematologic (8/56) tumors. Another noteworthy difference concerns the median time to diagnosis of peroneal neuropathy following the diagnosis of malignant disease, which was 5 months in the study of Rubin et al., whereas most patients were found to have been diagnosed within 1 month in our study. We excluded patients in whom peroneal neuropathy was diagnosed more than 6 months after the diagnosis of systemic malignant disease, if stable and nonprogressive. Weight loss was found in 35 of 58 patients in the study of Rubin et al. and in 35 of 56 patients in ours. We assume that factors other than weight loss (metabolic factors, for instance) may play a role in the development of peroneal neuropathy in cancer patients. It is unlikely that chemotherapeutic agents were causative factors in our patients, as only four patients received potentially neurotoxic drugs. A temporal relation with the occurrence of the peroneal neuropathy in these four patients made a correlation unlikely. We did not look at outcome figures for our patients. Rubin et al. reported relatively good outcomes. In conclusion, the findings of both studies confirm the relation between systemic malignant disease and the occurrence of peroneal neuropathy. In patients with peroneal neuropathy, cancer should be added to the list of associated conditions, particularly in elderly men. On the other hand, measures to prevent the occurrence of peroneal neuropathy during surgery and in bedridden cancer patients should be taken, particularly if weight loss has occurred. Pete J. Koehler M.D., Ph.D.*, Albert Twijnstra M.D., Ph.D. , * Department of Neurology, Atrium Medical Center, Heerlen, The Netherlands, Department of Neurology, University Hospital Maastricht, Maastricht, The Netherlands