A new study has reported that switching from one aromatase inhibitor to another when musculoskeletal side effects make the first one intolerable may allow some breast cancer patients to continue aromatase inhibitor treatment, thereby potentially improving their disease outcomes. Aromatase inhibitors typically are administered to postmenopausal women with hormone receptor positive breast cancer to reduce the conversion of androgens to estrogens in the body. In the study, 179 women who discontinued Arimidex (anastrozole) because of severe musculoskeletal side effects were switched to Femara (letrozole) and evaluated for six months. Musculoskeletal symptoms were evaluated for severity, location, presence of swelling, and presence of morning stiffness. The primary endpoint was the percentage of patients who also discontinued Femara due to musculoskeletal side effects. As of the end of the six-month study period, 128 (71.5%) of 179 patients were still taking Femara whereas 51 patients (28.5%) had stopped treatment because of severe joint pain. Most of the women continued to report musculoskeletal side effects as of the end of the study period: 116 patients (73.9%) reported arthralgia, 33 (21.0%) had myalgia, 25 (15.9%) had arthritis, 22 (14.0%) had tendonitis, and 20 (12.7%) had polyalgic syndrome. Duration of prior treatment with Arimidex was a significant predictor of stopping Femara treatment. The authors conclude that for patients intolerant to one aromatase inhibitor, switching to another allows a higher proportion of patients to continue aromatase inhibitor therapy and thereby maximize hormonal adjuvant therapy.
Certain foods can also reduce musculokeletal side effects
This study demonstrates that while all aromatase inhibitors have similar mechanisms of action, they may not have the same degree of musculoskeletal side effects in individual women. This means that women who cannot tolerate one aromatase inhibitor may be able to tolerate another, although some degree of musculoskeletal side effects are still likely to occur. Such treatment is important for those with hormone receptor positive breast cancer since it greatly reduces an important source of estrogen (and estrogen can support the growth of this type of breast cancer).
Women who take aromatase inhibitors can potentially reduce their musculoskeletal symptoms with certain foods, as well as vitamin D. The foods below can reduce these symptoms while at the same time protecting against breast cancer:
Certain foods also enhance the effectiveness of aromatase inhibitors, whereas others can interfere with them (see our web page on what to eat while taking an aromatase inhibitor).