Delayed radiation therapy after surgery significantly increased the risk of recurrent disease in women treated for very early breast cancer, study results presented at the American Association for Cancer Research 2016 Annual Meeting has shown. Very early breast cancer, or ductal carcinoma in situ (DCIS), is referred to as stage 0 breast cancer.1
The presence of abnormal cells in the milk ducts of the breast is the basis for DCIS diagnosis. DCIS is diagnosed in more than 60 000 women in the United States every year. Since the abnormal cells do not always become invasive breast cancer, experts dispute best treatment options. Typically, DCIS treatment includes lumpectomy, lumpectomy and radiation, or total mastectomy.
This study found that women were more likely to experience a recurrence of DCIS or higher-stage breast cancer in the same breast if they received no radiation therapy after lumpectomy or received radiation therapy 8 or more weeks after lumpectomy.
“This study indicates not only that radiation therapy is an important component in the treatment of DCIS but also that it must be received in a timely manner,” said Ying Liu, MD, PhD, instructor in surgery at the School of Medicine and a research member at Siteman Cancer Center at Barnes-Jewish Hospital and Washington University School of Medicine in St. Louis, Missouri, and lead author of the study.
Women who were black, unmarried, on Medicaid, whose diagnosis was made in the later years of the study, had larger tumors, or whose disease was not completely removed in surgery were more likely to experience delayed radiation therapy.
“These groups, especially, may benefit from undergoing radiation therapy sooner,” Liu stated.
Researchers examined data from 5916 women in the Missouri Cancer Registry with DCIS diagnosed between 1996 and 2011. All women included in the study were treated with lumpectomy. Of all women in the study, 28.8% (n = 1702) did not receive any radiation therapy as part of their initial treatment, and 17.8% (n = 1053) received radiation therapy 8 weeks or more after surgery. The remaining 53.4% received radiation therapy within 8 weeks of lumpectomy.
In women who received delayed radiation therapy, the risk of breast cancer recurrence was 26% higher than in women who received radiation therapy. In women who received no radiation therapy, the risk was 35% higher. These calculations were adjusted for age, race, pathologic factors, surgical margin status, and hormone therapy.
Average follow-up was 6 years, during which time 3.1% of women developed a recurrence of DCIS or an invasive tumor in the same breast. The recurrence rate was 2.5% in women who received radiation therapy within 8 weeks.
“What we’ve found suggests the need for more studies. Our hope is to provide clear-cut guidelines that will help more women reduce their risk of recurrence,” Liu said.
1. Liu Y, Yun S, Lian M, Colditz G. Radiation therapy delay and risk of ipsilateral breast tumors in women with ductal carcinoma in situ. Presentation at: American Association for Cancer Research 2016 Annual Meeting; April 16-20,2016; New Orleans, LA. /p<>