PLANTAR MELANOMA - A CASE-CONTROL STUDY IN PARAGUAY

In Paraguay, the plantar surface of the foot. is the most common site for malignant melanoma, as it is in several other populations worldwid e, most notably in I-hose of African descent, Here, pre report the res ults of the first case-control study of plantar melanoma, carried out in Paraguay. Sixty incident, histologically confirmed Eases of plantar melanoma and 256 hospital controls were recruited in 11 hospitals thr oughout the country during 1988-93. Information was collected on gener al demographic, social, and lifestyle variables, on external exposures of feet (shoewear, work activities, injuries), and on some constituti onal factors (skin, eye and hair collar, and pigmented lesions of the feet), Few of the factors examined appeared to be associated with the risk of plantar melanoma, adjusted for possible confounders, the stron gest association was found for reported injuries (odds ratio [OR] = 40 .9, 95 percent confidence interval [CI] = 14.8-112.7) and for occurren ce of naevi on the soles (OR = 5.9, CI = 2.5-14.3). Walking barefoot d id not seem to contribute to the risk although an outdoor workplace wa s associated with an increased melanoma occurrence (OR = 2.3, CI = 1.1 -4.8). Future studies should be aware of problems of recall bias with respect to previous injuries, and ensure that evaluation of pigmentati on of the sole is carried out blind to case/control status.