Commentary

The study by Chlebowski et al, gives detailed information regarding breast cancer risk in late postmenopausal women using oestrogen plus progestogen HT. No increased risk of breast cancer death was reported in HT users, and the diagnosis of metastatic breast cancer was observed in 1% of users compared with 2% of placebo users. The authors emphasised that HT users had larger tumours than placebo users (0.2 cm larger with a 10% greater node involvement [p≤0.04]). The recently released Million Women Study¹ found that current HT therapy, particularly oestrogen plus progestogen, was associated with increased risk of breast cancer. However, past use was not associated with such risk. It is becoming clear that current oestrogen plus progestogen HT carries greater breast cancer risk than oestrogen alone. Of note, the oestrogen only arm of the WHI is still ongoing.

Women and clinicians are receiving the message that HT increases breast cancer. Placing this in perspective for the menopausal woman² is important because there will continue to be women who want to use HT. In women with a uterus requiring progestogen opposition, it is likely that less use of synthetic progestogens and more use of localised vaginal uterine preparations will occur, particularly if it is proven that oestrogen alone is safer from the breast cancer perspective.

Because HT users had a substantially greater risk of abnormal mammography results than placebo users (9.4% v 5.4%, p<0.001), should women on HT stop using it for 2 weeks before an annual mammogram? It has been suggested that short term cessation of HT improves mammographic specificity.³ Although screening mammography is the current gold standard, a way to detect breast cancer before finding an abnormality on mammography is needed. Ductal lavage, recently approved by the US Food and Drug Administration, can be used as a risk assessment tool for women at high risk of breast cancer who have negative results on mammography. This may help menopausal women to make well informed decisions regarding HT, the use of tamoxifen for breast cancer chemoprevention, and other decision options related to the breast.⁴