It is clear that breast cancer rates plunged in recent years mainly because millions of women quit hormone therapy and fewer newly menopausal women started on it, said the study’s leader, Dr. Rowan Chlebowski of Harbor-UCLA Medical Center in Los Angeles.
“It’s an excellent message for women: You can still diminish risk (by quitting), even if you’ve been on hormones for a long time,” said Dr. Claudine Isaacs of Georgetown University’s Lombardi Comprehensive Cancer Center. “It’s not like smoking where you have to wait 10 or 15 years for the risk to come down.”
Study results were given Saturday at the San Antonio Breast Cancer Symposium…
The Women’s Health Initiative study had two parts. In one, 16,608 women closely matched for age, weight and other health factors were randomly assigned to take either Wyeth Pharmaceuticals’ Prempro — estrogen and progestin — or dummy pills.
This part was halted when researchers saw a 26 percent higher risk of breast cancer in those on Prempro.
But that was an average over the 5 1/2 years women were on the pills. For the new study, researchers tracked 15,387 of these women through July 2005, and plotted breast cancer cases as they occurred over time.
They saw a clear trend: Risk rose with the start of use, peaked when the study ended and fell as nearly all hormone users stopped taking their pills. At the peak, the breast cancer risk for pill takers was twice that of the others.