Aromatase inhibitors versus tamoxifen for premenopausal women with hormone positive early-stage breast cancer treated with ovarian suppression.

This study compared the effectiveness of aromatase inhibitors (AIs) versus tamoxifen (Nolvadex) for the treatment of premenopausal patients with estrogen receptor-positive (ER+) early-stage breast cancer (BC) treated with ovarian suppression. The data showed that AIs significantly reduced the risk of BC recurrence compared to tamoxifen in these patients.

BC is classified into different subtypes depending on the presence or absence of certain receptors (proteins found on the surface of the cancer cells). ER+ BC tests positive for the estrogen receptor (female sex hormone). Patients with this subtype of BC commonly receive hormone therapy which acts by decreasing the female hormones.

In women of reproductive age, the main hormonal therapy used is tamoxifen. This treatment works by blocking estrogen from reaching receptors (proteins) on cancer cells. AIs like anastrozole (Arimidex), exemestane (Aromasin), or letrozole (Femara) are other types of hormonal therapy. These work by lowering estrogen production and is used for treating BC in postmenopausal women.

AIs are more effective than tamoxifen in postmenopausal women but are ineffective in premenopausal women when used without ovarian suppression. Ovarian suppression drugs like goserelin (Zoladex) or triptorelin (Trelstar) stop the ovary from making estrogen. However, whether premenopausal women treated with ovarian suppression might benefit from AIs is still not known.

This study analyzed 4 studies and involved 7030 premenopausal women with ER+ early-stage BC. Patients were divided into 2 groups. Group 1 included patients who received AIs (anastrozole, exemestane, or letrozole) plus ovarian suppression (goserelin or triptorelin). Group 2 included patients who received tamoxifen plus ovarian suppression. The average follow-up time was 8 years.

AIs reduced the rate of cancer recurrence by 21% compared to patients who received tamoxifen. From the start of treatment to 4 years of follow-up, AIs reduced the rate of cancer recurrence by 32% compared to patients who received tamoxifen.

After 5 years, patients treated with AIs had a 6.9% risk of cancer recurrence compared to a 10.1% risk of cancer recurrence in patients treated with tamoxifen. AIs reduced the risk of cancer recurrence by 3.2% compared to patients who received tamoxifen. There was no further benefit or loss of benefit between the groups after 5 years of treatment.

AIs reduced the risk of distant recurrence by 17% compared to patients who received tamoxifen.

There were no significant differences in terms of overall survival, survival without cancer recurrence, and survival without breast cancer worsening between the 2 treatment groups.

Patients who received AIs were 1.27 times more likely to experience bone fractures compared to those who received tamoxifen.

This study concluded that aromatase inhibitors significantly reduced the risk of BC recurrence compared to tamoxifen in premenopausal women with ER+ early-stage BC receiving ovarian suppression.