Hormone replacement after menopause doubles the risk of developing breast cancer

December 23, 2008

According to a new analysis of a large federally funded study that reveals the most dramatic evidence yet of the dangers of still-popular pills to replace menopause hormones – taking them for five years doubles the risk of developing breast cancer. Even women who took estrogen and progestin pills for as little as a couple of years had a greater chance of getting cancer. When they stopped taking them, their odds quickly improved, returning to a normal risk level roughly two years after quitting. The study results were presented Saturday at the San Antonio Breast Cancer Symposium
It is clear that breast cancer rates plunged in recent years mainly because millions of women quit hormone replacement therapy and fewer newly menopausal women started on it, said the study's lead author, 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."
The researchers are part of the Women's Health Initiative, the group that tested estrogen and progestin pills that doctors long believed would prevent heart disease, bone loss and many other problems in women after menopause. The main part of the study was stopped in 2002 when researchers saw surprisingly higher risks of heart problems and breast cancer in hormone users.
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.
Fruits and vegetables cut the risk of developing breast cancer

Certain breast cancer survivors who load up on fruits and vegetables, eating far more than current U.S. guidelines, can slash their risk the tumors will come back by nearly a third, according to a U.S. study released on Monday. The finding only held for women who did not have hot flashes after their cancer therapy, the researchers said -- a finding that suggests fruits and vegetables act on estrogen.
Their analysis suggests an explanation for why some studies have shown that eating more fruits and vegetables lowers the risk that breast cancer will come back, while others do not; it may depend on the individual patient. "Women with early stage breast cancer who have hot flashes have better survival and lower recurrence rates than women who don't," said Ellen Gold of the University of California Davis, who helped lead the study.
Several studies have shown this. And this study showed that women who had hot flashes after treatment for breast cancer had lower estrogen levels than women who did not.
As estrogen drives the most common type of breast cancer, this suggests that eating extra servings of fruits and vegetables -- above and beyond the five servings a day recommended by the U.S. government -- may lower harmful estrogen levels in cancer survivors, the researchers said. The researchers collated data from 3,000 breast cancer patients in a study aimed at seeing whether a diet low in fat and high in fruits and vegetables might keep their cancer from coming back. Such a diet has been shown to lower overall risk of ever getting breast cancer in the first place. The women were on average 53, and half were told to double their fruit and vegetable intake to 10 servings a day, eat more fiber and lower fat intake more than government recommendations. "We compared the dietary intervention group to a group that received '5-a-day' dietary guidelines," the researchers wrote. About 30 percent of the original 3,000 breast cancer survivors said they did not have hot flashes -- a common side-effect of breast cancer treatment. The researchers looked at the data on these women specifically and found that only 16 percent of those who doubled up on fruits and vegetables had their tumors come back after seven years, compared to 23 percent of those merely given advice on food guidelines. Women who had been through menopause lowered their risk by 47 percent if they loaded up on salads, fruit and other plant food.
The study team was led by researchers at the Moores Cancer Center at the University of California, San Diego, along with six other sites, including the University of California, Davis.  The results were reported online ahead of print, December 15, 2008, in the Journal of Clinical Oncology.