The Pharmaceutical Journal
Vol 268 No 7199 p705-712
25 May 2002

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Tamoxifen is treatment of choice for preventing breast cancer recurrence

TAMOXIFEN should remain the therapy of choice for preventing the recurrence of breast cancer after surgery, an expert panel said this week.

The conclusions are drawn from an American Society of Clinical Oncology assessment on the use of aromatase inhibitors as adjuvant therapy for hormone receptor-positive breast cancer. The assessment involved a literature search and the collation of expert opinions.

Dr Eric Winer, director of the breast oncology centre, Dana-Farber Cancer Institute, Boston, Massachusetts, and chairman of the expert panel, said: "While recent findings on the use of aromatase inhibitors for the prevention of breast cancer recurrence are encouraging, data on long-term use of the drugs are needed before a change in the standard of care is justified."

The panel concluded that a five-year course of tamoxifen should remain the standard therapy for women with hormone receptor-positive breast cancer.

The assessment was conducted following the release of preliminary data from the ATAC (Arimidex, tamoxifen alone or in combination) trial last year, which indicate that anastrozole (Arimidex) might be more effective than tamoxifen at preventing breast cancer recurrence following surgery.

However, new results from the ATAC trial presented this week suggest that risk of endometrial cancer is lower with anastrozole than with tamoxifen.

The trial involved 9,366 patients who were randomised to receive 1mg anastrozole, 20mg tamoxifen or a combination of the two treatments. The latest data show that anastrozole is associated with significantly fewer cases of endometrial cancer compared with tamoxifen (0.1 per cent vs 0.5 per cent, P=0.03). In addition, incidence of vaginal bleeding, which can be an indicator of endometrial cancer, was lower in the anastrozole group (4.5 per cent vs 8.1 per cent, P<0.0001).

Dr Jeffrey Tobias, consultant oncologist, University College Hospital, London, and trial investigator, commented: "While tamoxifen has proven to be extremely beneficial in terms of reducing the number of breast cancer recurrences, it does come with a trade-off, namely the small but real risk of endometrial cancer." The study is funded by AstraZeneca.

Meanwhile, another study shows that completing chemotherapy before starting tamoxifen improves survival compared with taking the two treatments together.

A total of 1,477 women were randomised to receive either tamoxifen after chemotherapy, tamoxifen and chemotherapy simultaneously or tamoxifen alone. After eight years, 67 per cent of women who received tamoxifen after chemotherapy remained disease free compared with 62 per cent who received the two treatments together and 55 per cent who received tamoxifen alone.

When other factors that predict breast cancer recurrence were taken into account, this represented an 18 per cent advantage for completing chemotherapy before starting tamoxifen.