|NEWSRoom | Source: American College of Radiology|
RTOG Phase III Trial Shows Radiation Therapy Lowers the Risk of Breast Cancer Recurrence for Women Diagnosed with “Good Risk” DCIS
Ductal carcinoma in situ (DCIS)—the earliest and most curable breast cancer—accounts for approximately 20% of all new diagnoses. Prior studies of participants with both low and high-grade DCIS showed that whole breast radiation helps prevent the recurrence of both invasive and non-invasive (in situ) breast cancer after lumpectomy. The RTOG 9804 trial sought to determine the benefits of radiation therapy (RT) versus patient observation alone in a population of women determined to have “good risk” disease (Tamoxifen was allowed, though not required, in both arms). The criteria for “good risk” disease included: no evident cancer symptoms prior to detection by a mammogram or other imaging test, only low or intermediate nuclear grade cancer as determined by pathology review, and cancers no larger than 2.5 cm, and at least 3 mm of tissue surrounding the lumpectomy site (the margins) determined to be cancer free by local instruction pathologists.
The study opened to accrual in December 1999 and closed in July 2006 having enrolled 636 of the planned 1790 study participants with 287 cases and 298 cases eligible for analysis in the radiation therapy and observation arms respectively. Two of the women receiving RT had a breast cancer recurrence compared with 15 women in the observation arm. “The research team hypothesized that we could successfully develop criteria that would identify a cohort of very low risk DCIS patients,” says RTOG Principal Investigator Beryl McCormick, MD, Chief of External Beam Radiotherapy Service at Memorial Sloan-Kettering Cancer Center. “The low number of study participants who had a recurrence of their breast cancer strongly suggests we have developed criteria that identify good-risk DCIS patients, which is an important factor when evaluating treatment options for this patient population.”
While the overall number of women experiencing a breast cancer recurrence was small, the addition of RT showed a statistically significant reduction in breast cancer recurrence, with five-year rates of 0.4% and 3.2% for the RT and observation arms respectively. Women in the RT arm experienced more side effects than women in the observation arm with the increase in low-grade side effects being more pronounced. Grade 1 and 2 toxicities were 76% for the RT arm and 30% for the observation arm. RTOG will continue to follow the patients on this trial to assess long-term outcomes.
“This trial results can serve as one more piece of information for clinicians to consider in counseling patients with DCIS to determine if radiation is an appropriate option.” says Julia White, MD, chair of the RTOG Breast Cancer Working Group and a Professor in the Department of Radiation Oncology at the Ohio State Comprehensive Cancer Center.
Authors: B. McCormick, K. Winter, C. Hudis, E. H. M. Kuerer, E. Rakovitch, B. L. Smith, N. Sneige, A. Shah, I. Germain, A. C. Hartford, A. Rashtian, E. M. Walker, A. Yuen, E. A. Storm, J. L. Wilcox, L. A. Vallow, W. Small, Jr., A. T. Pu, K. Kerlin, J. White
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