Breast cancer in premenopausal women; hormone treatment with ovarian suppression

The authors aimed to determine the effectiveness of exemestane (Aromasin) to treat premenopausal women with breast cancer and treatment outlook in comparison to tamoxifen (Nolvadex).

Tamoxifen is a type of hormone therapy used to treat breast cancer. This type of treatment is generally specific for hormone receptor positive cancers (HR+; presence of hormone receptors on cancer cells). Tamoxifen can be accompanied by ovarian suppression treatment – this stops the ovaries from working properly and slows the growth of HR+ breast cancer in premenopausal women.

Exemestane is another type of hormone therapy. To date, the effects of exemestane with ovarian suppression treatment on premenopausal women with breast cancer are not well studied.

A total of 4,690 premenopausal women with breast cancer, all with HR+ cancer, were evaluated. 2,359 women were allocated to exemestane and ovarian suppression treatment while 2,358 women were allocated to tamoxifen and ovarian suppression treatment. The average follow up was 68 months. 

Overall, there was no significant difference in overall survival rates between the two treatment groups, with exemestane patients having a 96% survival rate compared to 97% for tamoxifen. However, after a follow up of 5 years, 93% of the women treated with exemestane were free from cancer. This was in comparison to 89% of the women who received tamoxifen. Exemestane reduced the risk of cancer recurrence (the cancer returns) by 34% compared to tamoxifen.

Twice as many women receiving exemestane, however, developed osteoporosis (condition that affects bone strength and increases the risk of a break; 13.2%) compared to those who were treated with tamoxifen (6.4%). Moderate to serious events that were most commonly reported included hot flushes, muscle or bone problems and high blood pressure, and were affected around 30% of both groups. 

The authors concluded that exemestane and ovarian suppression treatment provides a valid treatment option for HR+ breast cancer in premenopausal women, with a reduced risk of cancer recurrence.

Tamoxifen has been the standard of care for at least 5 years.

Discuss exemestane as a valid treatment option with your doctor if it applies in your case.