SUNDAY, Feb. 17 (HealthDay News) -- It's clear that chemotherapy after breast cancer surgery increases survival rates. But many older women aren't being offered this potentially lifesaving treatment.

But, age shouldn't be a deciding factor -- an older woman's general health appears to be a better predictor of positive results after chemotherapy, according to a study published recently in the Journal of the American Medical Association.

"Age alone should not be a contraindication to the use of optimal chemotherapy regimens in older women who are in good general health," the study authors said.

About half of all breast cancers in the United States occur in women older than 65. Past studies have shown that chemotherapy after breast cancer surgery increases the odds of disease-free survival in women between the ages of 50 and 69. But little information has been available for treating women over 70, the study authors said.

One important concern is that older women may experience more toxic side effects from chemotherapy. That's because the kidneys often function less effectively with age, and there's not as great a bone marrow reserve for generating new blood cells in older people.

"There's always been a concern that older women with breast cancer might be under-treated," said Dr. Yelena Novik, an oncologist at New York University Medical Center in New York City. "In clinical trials, the proportion of women over 70, and especially over 75, is very small, so it's hard to know the benefits and the risks. It's understood that older women are more likely to have other medical problems, such as heart disease, hypertension and diabetes, so the question is, should they be offered the same treatment as younger women?"

To answer that question, researchers from cancer centers around the country reviewed data from four previous trials that included almost 6,500 women with lymph-node positive breast cancer. Five hundred and forty-two of the women in the studies were over 65, and 159 were over age 70.

Each of the studies looked at various doses and regimens of chemotherapy, including regimens considered to be potentially more toxic than the others.

A number of factors influenced survival rates, including smaller tumor size, fewer positive lymph nodes, having more chemotherapy, and using the breast cancer drug tamoxifen. Age alone, however, didn't appear to influence survival rates, the study authors found.

Women over 65 were more likely to die of causes other than breast cancer. And they were slightly more likely to die as a result of the treatment than younger women were. Overall treatment-related mortality was 0.5 percent, and 1.5 percent for those women over 65.

"What this study basically showed is that we shouldn't prejudice our treatment decisions based on chronological age," said Dr. Jay Brooks, chairman of hematology and oncology at Ochsner Health System in Baton Rouge, La. "We have a lot of very healthy, older individuals, and to simply preclude someone from taking potentially lifesaving therapy because they've reached some chronological age is just wrong. Would you tell someone who's 68 with coronary vessel disease not to get a bypass?"

Both Novik and Brooks said that recent advances in tailoring breast cancer treatments to the individual patient have likely made the age disparity less of an issue.

"We're hopefully getting smarter in understanding cancer behaviors, which gives us better insight into which drugs to use," Novik said.

Brooks advised older women with breast cancer to "sit down and talk with their doctor about what their individualized risk of recurrence is. We have good tools to offer individualized treatment options, whatever your age."

More information

To learn more about chemotherapy treatment for breast cancer, visit the American Cancer Society.