“If a patient does not need to have radiation therapy, her quality of life can improve significantly,” says Kevin Hughes, MD, of the Massachusetts General Hospital (MGH) Cancer Center, who led the study. “By showing that radiation therapy has very little impact on outcome for these patients, we can help each woman and her physician decide on the right treatment.”
Many breast cancers depend on the hormone estrogen to grow. So tamoxifen, which blocks the interaction between estrogen and its receptor protein, is used to treatment tumors that have that protein on the surface of their cells. Most older breast cancer patients have receptor-positive tumors and receive tamoxifen, a medication that has few side effects.
Radiation has been a standard post-surgical treatment for women having lumpectomies, but the therapy can be both inconvenient and unpleasant, with side effects such as pain, swelling, and skin discoloration. Several studies have shown that, although radiation reduces tumor recurrence, it does not improve overall survival. Because breast cancer is less likely to recur in older women, the research team investigated whether such patients might do well if they receive tamoxifen alone after surgery.
Over a five-year period, more than 600 patients at almost 30 centers across the U.S. enrolled in the study. All the participants were age 70 or older, with early-stage (2 cm or less), receptor-positive tumors that had been removed in lumpectomy procedures. They were randomly assigned to receive either tamoxifen alone or tamoxifen plus radiation as postsurgical treatment.
At the end of the study period, the only significant difference between the groups was in the risk that the tumor would recur at or near its original site. Both groups had very low rates of recurrence; but while those in the tamoxifen-only group had a 4 percent risk, those who also received radiation had an only 1 percent risk. There were no significant differences in terms of distant metastasis, the need for mastectomy after recurrence or overall survival. Both groups had exactly the same number of breast cancer deaths – three in each group, a rate that reflects the less aggressive nature of breast cancer in this age group. As expected, those receiving radiation reported more pain, swelling, stiffness and other side effects than did the tamoxifen-only participants.
“The local recurrence risk in both groups was extremely low, and women who have not had radiation have the option of another lumpectomy if they do have recurrence in the same breast. Once a patient has had radiation, however, she must have a mastectomy if her tumor recurs,” says Hughes, an assistant professor of Surgery at Harvard Medical School. “In the long run, each woman and her physician should choose a treatment plan by weighing the slightly increased local recurrence risk against the virtually certain costs of radiation – the patient’s time, adverse effects, and financial costs.”
Supported by grants from the National Cancer Institute, the study was a collaboration among three major clinical research groups – the Cancer and Leukemia Group B (CALGB), the Radiation Therapy Oncology Group and the Eastern Cooperative Oncology Group. The report’s co-authors are Lauren Schnaper, MD, Greater Baltimore Medical Center; Donald Berry, PhD, Constance Cirrincione and Judith Wheeler, CALGB Statistical Center; Beryl McCormick, MD, Clifford Hudis, MD, and Larry Norton, MD, Memorial Sloan-Kettering Cancer Center; Brenda Shank, MD, PhD, Mt. Sinai School of Medicine; Lorraine Champion, MB, ChB, Alta Bates Comprehensive Cancer Center; Thomas Smith, MD, Morristown Memorial Hospital; Barbara Smith, MD, PhD, Massachusetts General Hospital; Charles Shapiro, MD, Ohio State University; Hyman Muss, Vermont Cancer Center; Eric Weiner, MD, and David Sugarbaker, MD, Dana-Farber Partners Cancer Center; William Wood, MD, Emory School of Medicine; and Craig Henderson, MD, University of California at San Francisco.
Massachusetts General Hospital, established in 1811, is the original and largest teaching hospital of Harvard Medical School. The MGH conducts the largest hospital-based research program in the United States, with an annual research budget of more than $400 million and major research centers in AIDS, cardiovascular research, cancer, cutaneous biology, medical imaging, neurodegenerative disorders, transplantation biology and photomedicine. In 1994, MGH and Brigham and Women’s Hospital joined to form Partners HealthCare System, an integrated health care delivery system comprising the two academic medical centers, specialty and community hospitals, a network of physician groups, and nonacute and home health services.
Journal
New England Journal of Medicine