FRIDAY, July 13, 2001 (HealthDayNews) -- A new study suggests that women receiving chemotherapy for early-stage breast cancer face a dramatically increased risk of rapid bone-density loss.
Experts say the findings could shift the emphasis on treatment for women with breast cancer to post-survival health issues.
Lead researcher Dr. Charles Shapiro, director of breast medical oncology at the Arthur G. James Cancer Hospital and Richard J. Solove Research Institute in Columbus, Ohio, expected to see early menopause and bone loss in some patients. But, he says, "I don't think we were expecting quite the magnitude of the loss and its appearance as early as it did."
The study appears in the July 15 issue of the Journal of Clinical Oncology.
Shapiro and his colleagues enrolled 49 premenopausal women whose cancerous tumors were either small or hadn't spread far beyond the breast. Within four weeks of starting chemotherapy, each woman was examined for bone density, hormone levels and markers of bone growth and loss.
After six months of cancer treatment, Shapiro found that 71 percent of the women lost ovarian function and experienced hormonal changes associated with menopause.
The same women showed dramatic bone loss at six and 12 months after treatment. "No one had documented how early it occurs," says Shapiro.
The women who lost ovarian function lost 8 percent of their bone mass, far more than the 1 percent to 2 percent normal postmenopausal rate of bone loss in the spine over a year.
The drop was so severe that a second part of the study, which would have randomly assigned the women to receive either a calcium nasal spray or a placebo spray after 12 months, was halted by an independent monitoring committee. Based on the extent of bone loss, the committee said giving some women placebos would be unethical.
However, the women in the study who retained their ovarian function experienced no significant drops in bone density.
Doctors have known for years that women who develop breast cancer and are treated with chemotherapy are likely to begin menopause early. Depending on the length of therapy, 50 percent to 70 percent of women treated for early-stage breast cancer go into early permanent menopause.
Even in patients without breast cancer, early menopause is a risk factor for osteoporosis, a generalized loss and thinning of bone that increases the risk of fractures, particularly in the spine, hips and wrists.
Dr. Richard Theriault, professor of breast medical oncology at the M.D. Anderson Cancer Center in Houston, says some pediatric cancer drugs have a direct effect on bone. But he says most evidence points to bone loss caused by the chemotherapy-induced early menopause, rather than the direct effect of anti-cancer drugs.
Dr. Patricia Ganz, director of the division of Cancer Prevention and Control Research at the Jonsson Comprehensive Cancer Center in Los Angeles, says, "we're provoking this problem at an earlier time, and it's probably more precipitous when we cause somebody to go into menopause very abruptly with chemotherapy."
Shapiro says he hoped to raise awareness of the problem and to encourage women who develop premature menopause to have their bone density checked. Those women should discuss their calcium and vitamin D intake and a moderate weight-bearing exercise regimen with their doctors, he says.
Shapiro soon will begin a trial of a drug called bisphosphonate zolendronic acid, or Zometa, to see when it prevents bone loss in premenopausal women receiving chemotherapy. Theriault says tamoxifen and raloxifene both have a positive effect on bone density in postmenopausal women.
Ganz, the author of an accompanying journal commentary, and Theriault both say that the study represents a shift towards consideration of the long-term consequences of cancer treatment, since early diagnosis and better therapies are improving survival rates.
"Looking at survivor issues -- fertility, bone mineral density, cardiovascular risks -- all of those become more important when you have improved survival," says Theriault.
"This paper will emphasize the need to discuss [the risk of bone loss]," he says. "It's clinically immediately applicable to practice
This is something that people need to know now."
What To Do
Read about bisphosphonates, drugs that prevent bone loss, from the Osteoporosis and Related Bone Diseases National Resource Center, or find out more about bone health from the National Osteoporosis Foundation.
The National Cancer Institute publishes this information on other chemotherapy side effects.
Find out about other medications linked to bone loss from Staten Island University Hospital.
