Protease inhibitors and carcinoma of the esophagus

BACKGROUND Squamous cell carcinoma of the esophagus is endemic in parts of South Africa. Previous case‐control studies have shown many associations but no clear etiologic pathway has been established. METHODS A case‐control study of dietary and social factors was performed for 130 patient/control pairs matched for age, gender, and educational level. Staple diet, consumption of wild vegetables, use of tobacco, and traditional beer consumption were compared between the two groups. RESULTS New significant associations were found with the consumption of beans (P = 0.016) and consumption of the full traditional diet of maize, pumpkin, and beans (P = 0.027). Known associations with the consumption of Solanum nigrum (P = 0.018) and with smoking (P = 0.002) were confirmed by multiple regression analysis. CONCLUSIONS Solanum nigrum, beans, and pumpkin all contain protease inhibitors. Suppression of protease inhibitors can lead to overexpression of growth factors in the esophagus, resulting in a proliferative and oncogenic drive. Cancer 1998;83:405‐408. © 1998 American Cancer Society. A case‐control study in an area in which esophageal carcinoma is endemic found a significant association between carcinoma of the esophagus and foods containing protease inhibitors. Unopposed action of growth factors in the esophagus may predispose certain individuals to carcinogenesis.