Percutaneous progesterone use and risk of breast cancer: Results from a French cohort study of premenopausal women with benign breast disease

Percutaneous progesterone topically applied on the breast has been proposed and widely used in the relief of mastalgia and benign breast disease by nu merous gynecologists and general practitioners. However, its chronic use ha s never been evaluated in relation to breast cancer risk. The association b etween percutaneous progesterone use and the risk of breast cancer was eval uated in a cohort study of 1150 premenopausal French women with benign brea st disease diagnosed in two breast clinics between 1976 and 1979. The follo w-up accumulated 12,462 person-years. Percutaneous progesterone had been pr escribed to 58% of the women. There was no association between breast cance r risk and the use of percutaneous progesterone (RR = 0.8; 95% confidence i nterval 0.4-1.6). Although the combined treatment of oral progestogens with percutaneous progesterone significantly decreased the risk of breast cance r (RR = 0.5; 95% confidence interval 0.2-0.9) as compared with nonusers, th ere was no significant difference in the risk of breast cancer in percutane ous progesterone users versus nonusers among oral progestogen users. Taken together, these results suggest at least an absence of deleterious effects caused by percutaneous progesterone use in women with benign breast disease .