Re: Breast Cancer Risk in Relation to the Interval Between Menopause and Starting Hormone Therapy

Extract

In a recent issue of the Journal, Beral et al. ( 1 ) reported on the Million Women Study (MWS) and confirmed that use of hormonal therapy either before or after menopause is not safe in terms of breast cancer risk. The false idea that hormonal therapy use before or after menopause is not associated with increased breast cancer risk has distracted from the increases in breast cancer risk and cancer-related mortality already described in the MWS and Women’s Health Initiative (WHI) trial ( 2 , 3 ). It is illogical to assume that taking hormones at any particular age is without risk because use of contraceptive estrogen–progestin increases the risk of several types of cancer, vascular diseases, and mortality in young women ( 4 ).

All hormonal contraceptives act predominantly more like progesterone rather than estrogen to avoid irregular bleeding. Combined hormonal therapy formulations also include powerful doses of progestins to avoid estrogen-induced endometrial hyperplasia and endometrial cancer in women with a uterus. Unfortunately, users of estrogen–progestin hormonal therapy have a higher risk of invasive breast cancer compared with users of estrogen-only hormonal therapy ( 1 , 5 ). Beral et al. ( 1 ) reported that current use of estrogen–progestin hormonal therapy approximately doubled the risk of breast cancer with less than 5 years of use (RR [relative risk] = 1.62, 95% CI [confidence interval] = 1.54 to 1.71) and more than 5 years of use (RR = 2.19, 95% CI = 2.10 to 2.27). In addition, less than 5 years of estrogen therapy use also increased the risk of breast cancer when use began either before menopause or less than 5 years after menopause (RR = 1.31, 95% CI = 1.19 to 1.43) ( 1 ). Currently, clinicians advise their patients to use hormonal therapy in the smallest doses for the shortest time period to suppress non–life-threatening menopausal symptoms. The findings reported by Beral et al. ( 1 ) indicate that this advice is potentially harmful to patients. Even so, the minor benefits of menopausal hormone use are still being lauded, although the WHI study did not find a statistically significant association between use of hormonal therapy during menopause and overall improvements in the quality of life of patients ( 6 ).