NEW ORLEANS — Women with ductal carcinoma in situ who received radiation therapy more than 8 weeks after breast-conserving surgery faced a significantly increased risk for ipsilateral breast tumors, according to an analysis of data from the Missouri Cancer Registry presented at the American Association for Cancer Research Annual Meeting.
Black women, single women and women insured through Medicaid appeared at greater risk for radiation delays, results showed.
“According to the National Comprehensive Cancer Network guidelines, primary treatment options for ductal carcinoma in situ [DCIS] include breast-conserving surgery plus radiation, total mastectomy and breast-conserving surgery alone,” Ying Liu, MD, MPH, PhD, instructor of surgery at Washington University School of Medicine and research member at Siteman Cancer Center in St. Louis, said in a press release. “This study shows that it is important for women to understand the benefits of timely receipt of radiation therapy after breast-conserving surgery.”
Liu and colleagues sought to assess the relationship between delays in radiation receipt and risks for subsequent ipsilateral breast events, as well as to identify potential factors associated with these delays, in women undergoing breast-conserving surgery for DCIS.
They identified 5,916 women diagnosed with first primary DCIS between 1996 and 2011 in the Missouri Cancer Registry.
The researchers defined radiation therapy delay as first receipt of radiation more than 8 weeks after breast-conserving surgery. They calculated propensity scores for radiation therapy delay compared with no delay during the first treatment course.
A total of 1,053 women (17.8%) received their first radiation therapy more than 8 weeks after surgery, and 1,702 women (28.8%) received no radiation during their first course of treatment.
Follow-up was 72 months, during which 3.1% (n = 182) of the cohort developed ipsilateral breast tumors.
Researchers observed a greater risk for ipsilateral tumors among women who received radiation more than 8 weeks after surgery (HR = 1.26; 95% CI, 1-1.59) and women who received no radiation (HR = 1.35; 95% CI, 1.03-1.76) compared with those who received timely radiation.
Factors associated with radiation delays included black race, single marital status, insurance through Medicaid, later year of diagnosis, larger tumor size and positive surgical margins.
Limitations of the analysis include the 72-month follow-up, and the small number of patients who developed ipsilateral breast tumors.
“Our preliminary findings need to be confirmed in a large cohort of patients with DCIS with a longer follow-up,” Liu said. “Future studies should also address the contributions of patient choice, health care providers, facilities and neighborhoods to therapy delay.” – by Cameron Kelsall
Liu Y, et al. Abstract 2576. Presented at: American Association for Cancer Research Annual Meeting; April 16-20, 2016; New Orleans.
Disclosure: The Foundation for Barnes–Jewish Hospital and the Breast Cancer Research Foundation provided funding for this study. Liu reports no relevant financial disclosures.