Past studies of radiation therapy in women with operable breast cancer have led to the conclusion that radiation therapy reduces the risk of recurrence of breast cancer but the effects on overall survival have been less clear. However, in some clinical trials, radiation therapy was given in inadequate or excessive doses or did not target an appropriate amount of tissue, including the chest wall and lymph nodes.
Val Gebski, of the National Health and Medical Research Council Clinical Trials Centre in New South Wales, Australia, and colleagues reanalyzed results from 36 clinical trials in which the use of radiation therapy was the sole difference between treatments given to breast cancer patients. They divided trials into three categories: category 1, for studies that used optimal radiation doses delivered to an appropriate amount of tissue; category 2, for studies where patients received an inadequate or excessive dose of radiation; and category 3, for studies in which an inadequate amount of tissue was treated with radiation therapy.
At 5 years, patients in category 1 studies had a 2.9% absolute increase in survival with radiation therapy than without. At 10 years, patients in category 1 studies had a 6.4% absolute increase in survival. In category 2 and 3 studies, radiation therapy was not associated with a difference in overall survival after 5 or 10 years of follow-up. Gebski and colleagues conclude that optimal radiation therapy improves patient survival, measured at both 5 and 10 years, and recommend that postmasectomy radiation therapy be considered for all patients at high risk.
Leonard R. Prosnitz, M.D., and Lawrence B. Marks, M.D., of Duke University Medical Center in Durham, N.C., in an accompanying editorial, praise the authors' report, "It seems like such a simple idea. It is surprising that no one has ever done it before." Prosnitz and Marks suggest that, despite the limitations of the meta-analysis format used, the results show that the quality of radiation therapy positively affects survival outcomes. They write, "The evidence is now strong for survival benefits for both postmastectomy radiation therapy and postlumpectomy radiation therapy."
Article: Val Gebski, Biostatistics and Research Methodology, NHMRC Clinical Trials Center, University of Sydney, 61-2-9562 5000, email@example.com
Editorial: Leonard Prosnitz, Duke University Medical Center, 919-668-7342, Leonard.firstname.lastname@example.org
Article: Gebski V, Lagleva M, Keech A, Simes J, Langlands AO. Survival Effects of Postmastectomy Adjuvant Radiation Therapy Using
Biologically Equivalent Doses: A Clinical Perspective. J Natl Cancer Inst 2006;98:26-33.
Editorial: Prosnitz LR, Marks LB Postmastectomy Radiotherapy: Quality Counts! J Natl Cancer Inst 2006; 98:3-4.
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