Spironolactone and Fibroadenomas

Spironolactone and Breast Fibroadenomas

Spironolactone is a medication which functions in part as an anti androgen. It is used in the treatment of female pattern hair loss. Spironolactone has several uncommon breast related side effects including rare beast tenderness and rarely breast enlargement.. As I reviewed last year, there is no good evidence that spironolactone causes breast cancer.

ARTICLE: No Evidence for Increased Breast Cancer Risk From Spironolactone

Spironolactone Benign Fibroadenomas of the Breast

A question I am often asked is whether spironolactone could be implicated in causing being breast fibroadenomas. This has not been carefully studied in women to any extent. There was, however, a study dating back to 1990 in which a suggestion was made that spironolactone might be implicated in causing fibroadenomas. The study was a report of a 69-year-old man with congestive heart failure who had been treated with digoxin for 27 years and spironolactone for 4 years developed bilateral breast enlargement (gynecomastia). The excess tissue was removed and was shown to contain multiple nodules. Under the microscope (i.e. histologically), the nodules showed a pattern corresponding to fibroadenoma of the female breast. The author concluded that this so called "fibroadenomatoid hyperplasia," was probably caused by treatment with spironolactone.

This study was of course in a male and the role of the dioxin in the patent’s development of fibroadenomas is not clear. Digoxin also has an effect on causing gynecomastia and one must consider whether an interaction between dioxin and spironolactone could somehow be relevant.

Conclusion

More studies are needed whether there is any true relationship between fibroadenomas and spironolactone use. Mechanistically, and pathophysiologically, it certainly is possible. That however is a big leap between possible and actual causing the disease.

Reference

Nielsen BB. Fibroadenomatoid hyperplasia of the male breast. Am J Surg Pathol. 1990.