UF researchers find radiation prolongs survival for certain breast cancer patients
Aggressively tackling invasive breast cancer with a trio of treatments — surgery, chemotherapy and, notably, radiation — helps certain women remain disease-free longer, University of Florida researchers report.
“We know from patterns of recurrence after mastectomy that there’s oftentimes microscopic residual disease left behind that leads to a recurrence of the disease in the chest wall or in the lymph nodes, so the goal of the radiation is to eliminate the microscopic residual disease we suspect is present, thereby reducing the risk of regional recurrence and of distant metastases from the primary breast cancer,” said Nancy Mendenhall, M.D., chairwoman of the department of radiation oncology at the University of Florida College of Medicine.
“It’s very much to the advantage of breast cancer patients to be evaluated initially by a multidisciplinary team of physicians, including surgical oncologists, radiation oncologists and medical oncologists who specialize in the management of breast cancer,” she added. “If their breast cancer is sufficiently extensive to require mastectomy, they may benefit from the addition of radiation.”
Although radiation therapy has been used for many years to treat some breast cancer patients, the practice has not been widely adopted because of controversy over its benefits.
Scientists affiliated with the UF Shands Cancer Center studied more than 300 patients who underwent electron-beam radiotherapy after mastectomy between 1978 and 1998 at Shands at UF medical center, assessing patterns of disease recurrence, prognostic factors and overall outcome. Disease-free survival rates at 10 years were approximately 75 percent for patients with three or fewer lymph nodes involved and approximately 50 percent for patients with three or more lymph nodes involved.
The findings appeared recently in the online edition of the International Journal of Radiation Oncology Biology Physics, which will publish the study in its July 1 print edition.
Prospective, randomized trials in Europe and Canada suggest the addition of radiation after mastectomy results in about a 10 percent improvement in overall survival, said Mendenhall, also the Rodney R. Million, M.D., professor of radiation oncology and a co-author of the paper. That news has helped quell the debate over radiation’s use for certain patients.
Patients with tumors larger than 5 centimeters — about the size of a small grape — or primary tumors located close to surgical margins clearly benefit from radiation therapy, but physicians suspect radiation also might help some patients with smaller, aggressive tumors between 2 and 5 centimeters, Mendenhall said.
One in eight American women will develop breast cancer during their lifetime, according to the National Cancer Institute.
In the UF study, one of the first to report long-term results after mastectomy and electron-beam radiation, researchers tracked patients for 10 years. UF physicians have customarily added radiation therapy to the treatment regimen for patients at intermediate or high risk of a recurrence in the chest wall or regional lymph nodes.
“Using radiation after mastectomy is important for many women who undergo mastectomy,” said Lawrence J. Solin, M.D., a professor of radiation oncology at the University of Pennsylvania School of Medicine. “This study from the University of Florida demonstrates high rates of success and acceptable rates of complications after postmastectomy radiation treatment. With the increasing success of contemporary breast cancer treatment, long-term outcome studies such as this study, give important information to help us understand the best methods to treat our patients today to maximize cure and minimize complications.”
Postmastectomy radiation was hypothesized to be beneficial both for increasing local and regional disease control and also improving survival, but early trials in postmastectomy radiotherapy failed to demonstrate anticipated benefits, Mendenhall said.
“We felt here very strongly that the treatment did work and that possibly there were reasons why the trials failed to show benefits,” she said.
Previous studies, conducted before CT scanning revolutionized treatment planning for breast cancer patients, were limited by their ability to deliver radiation therapy accurately and to stage cancer properly, she said.
“We believe adding radiation is the right thing to do,” Mendenhall said. “In the randomized trials reported in the late ’90s, there was at least a 10 percentage point improvement in survival with the addition of radiation in all subgroups. It’s very clear that all patients with positive lymph nodes have a significant reduction in local recurrence, regional recurrence, distant metastases and death from breast cancer if radiation is added after mastectomy. In addition, there are patients without positive lymph nodes who may also be at high risk for local recurrence and thereby benefit from the radiation. These patients could be identified by tumor size, grade, location and other pathologic features.”
Radiation can cause temporary and occasionally permanent skin changes, and contribute to the risk of arm swelling. Rarely, the therapy damages the heart or lungs, or makes patients more prone to rib fractures. But UF researchers use a method of delivering the treatment called electron-beam radiotherapy, which they say is more likely to be accurate and to minimize adverse effects.
“It has the advantages of decreased radiation exposure to normal tissues, including the heart and lungs, and also the advantage of increased likelihood of treatment accuracy,” Mendenhall said. “In other words, it got us around some of the technical problems that probably flawed the early trials and precluded documentation of the benefits of radiation. This technique kept us from making the same technical mistakes that were probably made in some of the early randomized trials.”