Combo HRT tied to delayed detection of breast cancers: expert urges caution in applying these findings to younger women.(Elevated Breast CA Risk)

Invasive breast cancer is detected at a more advanced stage in women who are on estrogen-progestin therapy, compared with those who develop the disease while taking a placebo, according to a new analysis of data from the Women's Health Initiative.

The analysis also showed that women taking combination therapy were significantly more likely to have an abnormal mammogram requiring further follow-up, even after just 1 year of use.

Women in the combination therapy group were found to have a significant 24% increase in their relative risk of breast cancer when evaluated an average of 5.6 years after initiating hormone use, an increase similar to that seen in last year's results reported after an average of 5.2 years. In terms of absolute risk, the excess risk per 10,000 women on combination therapy was eight additional breast cancers per year (JAMA 289[24]:3243-53, 2003).

"The ability of combined hormone therapy to decrease mammographic sensitivity creates an almost unique situation in which an agent increases the risk of developing a disease while simultaneously delaying its detection," according to Dr. Peter H. Gann and Dr. Monica Morrow of Northwestern University, Chicago, commenting in an accompanying editorial (JAMA 289[24]:3304-06, 2003).

Still, clinicians must be careful not to extrapolate these findings to all menopausal women, Dr. Lee Shulman, professor of obstetrics and gynecology and head of reproductive genetics at Northwestern, said in an interview.

The WHI trial included women between the ages of 50 and 79 years, with a mean age of 63 years. "The population base studied in the WHI trial is not the population that we typically discuss hormone therapy with, which is a younger population who are just entering menopause and who desire hormone therapy primarily for osteoporosis prevention and symptom relief," explained Dr. Shulman, who is on the speakers' bureau for Solvay, which markets hormone therapies.

Natalie de Vane, a spokesperson for Wyeth Pharmaceuticals, which makes the Prempro formulation used in the WHI (0.625 mg/day conjugated equine estrogen and 2.5 mg/day medroxyprogesterone acetate), noted in an interview that "it's important that women understand that hormone therapy is not a lifetime commitment. It's a short-term treatment for menopausal symptoms."