Study on Anastrozole and Breast Cancer Recurrence

Background on Anastrozole and Breast Cancer

A recent study examined the efficacy of anastrozole in reducing the risk of breast cancer recurrence. Estrogen, a hormone that promotes the growth and survival of both normal and cancerous breast epithelial cells, plays a significant role in the development of certain breast cancers. Those that are particularly sensitive to estrogen are classified as estrogen receptor (ER)-positive breast cancers.

Anastrozole belongs to a group of medications known as nonsteroidal aromatase inhibitors. These agents are effective in slowing or halting the growth of various types of breast cancer cells that rely on estrogen. Anastrozole achieves its effects by decreasing estrogen production in the body’s fat tissue, while not affecting ovarian estrogen levels. Consequently, this treatment is primarily suited for postmenopausal women.

Findings from the Recent Study

A study published in the Lancet reported that five years of anastrozole treatment (Arimidex) successfully and safely prevented breast cancer recurrence in high-risk postmenopausal women, with a follow-up period extending to 12 years. This research strengthens the argument for utilizing anastrozole in the prevention of breast cancer among women at high risk.

The study involved a large multicentric trial, including 3,864 postmenopausal women (1,920 received anastrozole and 1,944 received a placebo) enrolled between 2003 and 2012. Researchers monitored these participants for a total of 12 years post-treatment. Results indicated that the likelihood of breast cancer recurrence was reduced by 49% in women who received anastrozole compared to those on placebo.

Impact of Anastrozole on Recurrence Rates

The most significant reduction in recurrence occurred within the first five years of anastrozole treatment, showing a 61% decrease. Even during the post-treatment follow-up period, a notable reduction of 37% persisted, surpassing the effects of tamoxifen. Additionally, the incidence of invasive ER-positive breast cancer was reduced by 54%, maintaining significant effects even after treatment concluded. A marked reduction in ductal carcinoma in situ was also observed, particularly among ER-positive patients.

Additional Observations and Considerations

Anastrozole treatment was associated with a significant decrease in non-breast cancers, particularly non-melanoma skin cancer. However, no impact on cancer-specific mortality was noted. It is important to consider that the participants were younger, underscoring the necessity for extended follow-up studies to fully assess long-term outcomes.

Conclusion

This study highlights the potential of anastrozole as a preventive measure against breast cancer recurrence in high-risk postmenopausal women, reinforcing its importance in breast cancer management strategies.

Written by Purnima Sharma, PhD
Reference: Cuzick J, Sestak I, Forbes JF, Dowsett M, Cawthorn S, Mansel RE, Loibl S, Bonanni B, Evans DG, Howell A. Use of anastrozole for breast cancer prevention (IBIS-II): long-term results of a randomized controlled trial. Lancet. 2020; 395: 117-122. Image by marijana1 from Pixabay