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.