Reactions 481 - 11 Dec 1993

Concerns over tamoxifen’s safetyThe recruitment of thousands of volunteers for trials

of tamoxifen in breast cancer prevention has led toconcerns over the safety of the agent.

The main concern is whether tamoxifen causes livercancer in humans as it has been shown to do in rats.

Professor VC Jordan from the NorthwesternUniversity Medical School, Chicago, US, argues that theobjections currently being made over tamoxifen couldalso equally apply to oral contraceptives. Oralcontraceptives are also associated with hepatic tumoursin rats and increase the risk of hepatocellular carcinomain women. But epidemiologists consider the increasedrisk of hepatocellular carcinoma with oralcontraceptives is insignificant and is far outweighed bythe benefit of preventing pregnancy. Hepatocellularcarcinoma occurs in 5 per 100 000 women receivingoral contraceptives in western countries.

In comparison, the incidence of hepatocellularcarcinoma in patients receiving tamoxifen is unknown.But in the estimated 4.5 million women years ofexperience with tamoxifen to date, only 2 cases ofhepatocellular carcinoma have been reported in womenreceiving a dose of 40 mg/day.Jordan VC. How safe is tamoxifen? Only large randomised controlled trials candecide. BMJ 307: 1371-1372, 27 Nov 1993 800236766

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Reactions 11 Dec 1993 No. 4810114-9954/10/0481-0001/$14.95 Adis © 2010 Springer International Publishing AG. All rights reserved