December 5, 2008 — As many as 20% of older women experience delayed or incomplete radiation treatment after breast-conserving surgery, and this can adversely affect disease-free survival. The study, published in the December 1 issue of Cancer, also showed that nonwhite race negatively influenced timely receipt of radiation therapy.
In a sample of 7791 women with stage I cancer or ductal carcinoma in situ (DCIS) 65 years and older, 1297 experienced delayed radiotherapy and 269 had incomplete radiotherapy. Stage I breast cancer patients with delayed radiation therapy were more likely to experience a subsequent breast event (odds ratio [OR], 1.14). The rate of overall mortality was also higher among stage I breast cancer patients with incomplete radiation therapy (OR, 1.32).
"Timeliness of post-surgical radiotherapy is important in reducing the risk of subsequent recurrence or new breast malignancies in patients with early breast cancer. Delaying treatment by 8 weeks or more significantly increased the odds for recurrence," said lead author Heather Taffet Gold, MD, assistant professor of public health in the Division of Health Policy in the Department of Public Health at Weill Cornell Medical College, in New York City, in a statement. "One possible reason for the delays is that the coordination of care can be a challenge, as treatment is usually delivered by multiple providers from different specialties, including surgeons, radiation oncologists, and medical oncologists,"
An exploratory analysis suggested that a delay in radiation therapy of 12 or more weeks after surgery, or 8 or more weeks after chemotherapy, were more than 4 times more likely to experience a subsequent breast cancer event, regardless of stage. For all patients, noncompletion of radiation therapy was not associated with an increased risk for recurrence or relapse, but among those with stage I disease, incomplete radiotherapy was associated with worse overall survival (OR, 1.32).
Even though radiation therapy after breast-conserving surgery has been shown to reduce the risk for local recurrence, statistics suggest that many patients have received suboptimal treatment. As an example, the authors note that only 39% of women 65 years and older with DCIS receive postlumpectomy breast irradiation, whereas 80% of patients with early invasive breast cancer received radiotherapy after a lumpectomy.
Race and Poverty Level Associated With Delayed Treatment
Dr. Gold and colleagues used the Surveillance, Epidemiology, and End Results (SEER)-Medicare database to identify women who were diagnosed from 1991 to 1999 with a first primary DCIS or stage I breast cancer. The median follow-up time was 6.3 years for DCIS (n = 1026) and 5.9 years for stage I disease (n = 6765), and ranged from 1 to 9 years.
They found that 16% of the women had experienced a delay in the initiation of radiation therapy of more than 8 weeks after surgery, or more than 4 weeks after chemotherapy, and this included all stages. Approximately 3% of the patients in this cohort also did not complete the full course of radiation treatment.
Chi-square testing revealed that women residing in an area of high poverty were more likely to have a delay in radiation therapy (P =.09 for stage I only) and noncompletion (P = .03 for stage I). Race was also associated with a higher probability of delaying treatment among women with stage I disease, and black women were more likely to delay treatment than white women (OR, 1.56). Patients residing in areas where there was a high density of radiation oncologists were less likely to delay therapy (OR, 0.73).
Analysis showed that factors predictive of a lower probability of a subsequent breast cancer event included older age, lower levels of poverty, higher density of radiation oncologists, and being married. Because density of radiation oncologists in an area improved both disease-free and overall survival, the researchers note that this factor might be an indicator of access to healthcare services.
The effect of delayed radiation therapy on disease-free survival in both DCIS and early invasive breast cancer patients has not been evaluated in randomized clinical trials, the authors say. "This nationally representative population-based study of older women with DCIS or early invasive breast cancer included women who are often underrepresented in randomized controlled trials, and gave us a unique opportunity to study delay and noncompletion of radiation therapy."
To improve health outcomes after treatment for early invasive breast cancer, clinicians need to intervene in the care process to reduce delay time and encourage completion, they conclude. "Facilities and providers should implement supportive services and provide educational materials to encourage and ease access to optimal [radiation therapy], thereby improving [disease-free] and overall survival."
The study was supported by the American Cancer Society.
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