A great deal of attention is being paid to the benefits and harms produced by both screening tests and treatments for various types of cancer. The microscope has been turned on radiation therapy (radiotherapy) being used with older breast cancer patients.
Despite the fact that a large clinical study demonstrated that radiotherapy offers only limited benefit for older women with early breast cancers, radiation treatment is still being used with these patients.
A new study conducted by researchers at Yale School of Medicine finds that practice does not always change following clinical trial results
“We were surprised by these results,” said lead author Cary P. Gross, M.D., Yale associate professor of internal medicine. “Clinical trials are considered the gold standard of medical research and in this case the trial was influential enough to lead to a change in treatment guidelines. We expected it to have more of an impact on clinical care at the bedside.”
The usual course of treatment for early stage breast cancer involves a lumpectomy followed by radiation to kill any remaining cells in an effort to reduce the chances of the disease returning. Many older women, however, have less aggressive cancers that are less likely to recur.
This study looked at the impact of a large trial funded by the National Cancer Institute (NCI) trial and published in 2004. The findings revealed limited benefit from radiation in women over the age of 70 with early, low-risk breast cancer.
Treatment guidelines were changed as a result of this trial, stating that radiotherapy should be considered optional for these patients.
Despite these findings, practice has changed very little, according to Dr. Gross and colleagues. Among Medicare beneficiaries, about 79 percent of women received radiotherapy prior to the study and 75 percent after.
This held true even for the oldest women, aged 85-94 years. Radiotherapy was used for 37 percent of these patients before the study and 33 percent after.
“These findings have important implications for how the results of clinical research studies are translated into practice,” said Dr. Gross, who points out that the U.S. government invested over $1 billion in comparative effectiveness research as part of the American Recovery and Reinvestment Act of 2009. “Our societal interest in funding this type of research is appropriate, and the need is great, but we must ensure that the results of such research extend beyond the journal page and are actually incorporated into clinical decision-making.”
dailyRx asked Benjamin Smith, M.D., assistant professor in radiation oncology at The University of Texas MD Anderson Cancer Center to comment on this study. “While this finding could simply reflect entrenched medical practice that is not responsive to new research, there are also several important alternative reasons why this trial may not have substantially impacted care patterns,” said Dr. Smith, who was not involved in the either the original trial or the Yale follow-up observational study.
“First, although the trial showed little benefit from radiation, it still did show a small benefit from radiation with respect to prevention of breast cancer recurrence in the breast. Many patients, even after thorough counseling, choose to receive radiation for its small but documented benefit.
“Second, the trial was too small to identify subgroups of patients who might be more or less likely to benefit from radiation, so it has been difficult to know how to apply its findings to very specific patient situations, for example patients with high grade tumors, close margins, lymphovascular invasion, or lobular histology.
“Finally, the trial showed that five years of endocrine therapy could substitute for 6 weeks of radiation therapy. However, many patients either cannot tolerate or refuse to take daily endocrine therapy for five years; in such cases radiation may actually be a less toxic and easier alternative. These issues with the trial may have influenced its acceptance and could explain its limited impact on care patterns subsequent to its publication,” Dr. Smith explained.
The Yale study appears in the March, 2012 Journal of Clinical Oncology.
The National Cancer Institute funded the study.
In the United States, one out of every eight women will be diagnosed with breast cancer sometime in her life. In 2010, there were over 250,000 new cases of breast cancer in women, and the number is rising. While treatment is improving, almost 40,000 women still died from breast cancer during 2009. However, there are still 2.5 million women in the US who are survivors.
Breast cancer, like any other cancer, is malignant, uncontrolled growth of breast tissue, usually from the tissue that lines the milk ducts (ductal carcinoma) or the tissue that makes the milk (lobular carcinoma). When cancer has not invaded other parts of the breast, it is referred to as in situ. (ex. Ductal carcinoma in situ). Breast cancers are also defined by their genes and hormone sensitivity. Some grow in response to the presence of estrogen, and area called ER+. Others have specific genes that make the cancer more aggressive, such as the gene HER2. These are important distinctions that direct treatment and prognosis.