Can tamoxifen reduce the risk of cancer-related mortality?

The authors aimed to determine whether long-term adjuvant (treatment given after the primary treatment) tamoxifen (Nolvadex) can reduce the risk of death by cancer in pre-menopausal women with estrogen-receptor positive (ER+) breast cancer.

Long-term adjuvant tamoxifen treatment showed a reduction in the risk of death due to breast cancer for up to 26 years.

ER+ breast cancers are those dependent on the estrogen hormone for growth.  Tamoxifen is a common hormone therapy drug used to treat ER+ breast cancer.  It blocks the actions of estrogen, preventing the growth of the tumor.

It is thought that the use of tamoxifen for up to 2 years can significantly increase recurrent-free survival (RFS; time from treatment until cancer returns) for an average of 14 years. It is not fully understood whether tamoxifen can extend its effect on the risk of death beyond 15 years.

The aim of this study was to evaluate the effects of long-term tamoxifen use on the mortality rate of women with ER+ breast cancer.

A total of 564 women with stage 2 breast cancer (tumor is growing but contained to the breast) were evaluated for this study. Random grouping assigned 276 of the women to 2 years of tamoxifen, while the remaining 288 received no treatment (control group).

65% of the women in the tamoxifen group and 69% of the control group had ER+ breast cancer. 137 of the women were treated with 40 mg of tamoxifen per day and 427 received 20 mg per day.

The use of tamoxifen showed a 37% reduced cancer-related mortality in the women with ER+ breast cancer. Tamoxifen also led to a 33% reduced overall mortality risk, but this was not statistically significant.

Tamoxifen reduced the cancer-related mortality risk by 63% for patients younger than 40, compared to 13% in those over 40.

The most significant effect was seen during follow-up years 5 to 15, as tamoxifen reduced the risk of mortality by almost 50%.

250 of the original patients were still alive after the 26 year follow-up.

The authors concluded that 2 years of tamoxifen treatment can give prolong survival for pre-menopausal women with ER+ breast cancer.

The tamoxifen dosage differed between the two groups in the different regions. Although both doses provided similar results, further tests should be carried out to provide a globally standard treatment.