For women who have had surgery for early breast cancer, it may not matter whether they receive follow-up chemotherapy before, after or during radiation therapy, according to a new review of studies.
A woman's chances of survival or seeing the cancer return are similar in all three cases, if radiation therapy and chemotherapy begin within seven months after surgery, the review concludes.
However, the studies suggest that certain toxic side effects in the blood and esophagus -- common in chemotherapy and radiation patients -- may be up to 44 percent more likely when the two therapies are delivered at the same time, said Dr. Brigid Hickey and colleagues at the Southern Zone Radiation Oncology Service in Brisbane, Australia.
The reviewers also note that most of the women in the studies were treated about 10 years ago. "As a result, the trials do not assess the modern types of radiotherapy and newer types of chemotherapy" and other anti-cancer drugs such as Herceptin, Hickey said.
Studies show that radiation therapy can reduce the risk of breast cancer returning in the treated breast and boost the likelihood of survival after breast cancer surgery. Doctors may also prescribe chemotherapy to women at high risk for having the cancer spread to other parts of the body after surgery, to reduce the risk of dying from breast cancer.
"However, the best sequence of administering these two types of therapy for early stage breast cancer is not clear," Hickey said.
"As far as I know, there are few good randomized trials evaluating the different timing of radiation. This is one of the problems about deciding on what the best approach is here," said Dr. Tim Whelan, a radiation oncologist who specializes in breast cancer treatment at McMaster University in Ontario, Canada.
Hickey and colleagues found only three high-quality studies, comprising 1,097 patients, that compared different sequences of radiation and chemotherapy after breast cancer surgery.
The finding may reassure those who begin chemotherapy while waiting for radiation treatment, which is limited in many parts of the world, the Cochrane researchers said.
"The delivery of chemotherapy first allows patients to continue with their treatment while they wait for radiotherapy to start, and this may make management of the waiting lists for radiotherapy easier," Hickey said.
Whelan said his clinical practice usually gives chemotherapy first followed by radiation. His practice follows a suggestion from an earlier study and "a clinical impression" that giving chemotherapy first reduces the risk that the cancer will reappear in a distant part of the body. But Whelan acknowledged that the risk of recurring cancer in the breast may be slightly higher when radiation is delayed.
By Becky Ham, Science Writer Health Behavior News Service
The Hickey review was supported by the Princess Alexandra Hospital Cancer Collaborative Group in Australia.
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Hickey BE, Francis D, Lehman MH. Sequencing of chemotherapy and radiation therapy for early breast cancer. The Cochrane Database of Systematic Reviews 2006, Issue 4.
The Cochrane Collaboration is an international nonprofit, independent organization that produces and disseminates systematic reviews of health care interventions and promotes the search for evidence in the form of clinical trials and other studies of interventions. Visit http://www.cochrane.org for more information.