Increasing the Risk

When the records of hospital patients are analyzed by a computer, the electronic brain sometimes makes surprising discoveries by collating and relating data that a human mind would take many years to process. This has happened in the Boston metropolitan area, where a Boston University team led by Dr. Hershel Jick analyzed the records of 25,000 patients admitted to 24 hospitals in 1972. The surprise finding, reported in the British medical journal the Lancet, is that women aged 50 or over who take certain types of medication to relieve mild cases of high blood pressure run a threefold increased risk of developing breast cancer.

Some 10% to 20% of all U.S. women in the over-50 age group have some degree of hypertension, and hundreds of thousands of them are being medically treated for the condition. Most of these patients take a small daily dose of reserpine or a related alkaloid, both extracted from the roots of the Indian shrub, Rauwolfia serpentina. The rauwolfia products have been in use for 20 years, have generally been well tolerated in the dosage used by patients, and are inexpensive compared with newer medications for lowering blood pressure, such as guanethidine and methyldopa. The Boston team listed six products containing reserpine, usually in combination with a diuretic medication, that had been prescribed for the patients studied; dozens more are sold in the U.S. and other countries.

Cautious Checks. The investigators found that eleven, or 7.3%, of 150 women with newly diagnosed breast cancer had been taking reserpine medicines, whereas only 2.2% of 1,200 patients without breast cancer (but otherwise similar to the cancer-stricken women in age and other characteristics) had taken them. They reanalyzed their data to rule out hypertension itself as a cause or accelerator of breast cancer and also found no association with the alternative hypertension drugs. Cautious to a degree and determined not to be alarmist, the Boston group invited eminent epidemiologists in England and Finland to run a similar check. Their results were essentially the same.

Theories as to how reserpine-type alkaloids might influence breast cancer are inconclusive. A leading U.S. cancer epidemiologist, Manhattan's Dr. Ernest L. Wynder, believes that the action is not to cause the cancer--that usually takes many years--but to stimulate or accelerate its development. A somber Lancet editorial suggests that doctors will now have to weigh the apparently greater risk of breast cancer against the advantages of lowering blood pressure for mature women.

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