Radiation therapy (RT) improved survival rates among older women with early-stage, low-risk breast cancer, according to research presented at the American Society for Radiation Oncology (ASTRO) meeting in Boston. Researchers recommended that treatment guidelines be updated to include these findings.
In 2005, National Comprehensive Cancer Network (NCCN) treatment guidelines were revised after randomized controlled trials failed to demonstrate a survival advantage of RT after breast-conserving surgery in elderly women with early-stage, estrogen-receptor positive (ER+) breast cancer.
Mariam P. Korah, MD, radiation oncologist at the University of Southern California Keck School of Medicine in Los Angeles, and colleagues sought to assess changes in patterns of care and survival rates for this population. The researchers reviewed patient records of 27,559 women from the Surveillance, Epidemiology and End Results (SEER) database from 2000 to 2008. All women were older than 70 years of age, had early-stage, ER+, node-negative breast cancer and had completed breast-conserving surgery with a minimum three-month follow-up.
The analysis showed women who underwent RT had an 87 percent overall survival rate at five-year follow-up and 73 percent at eight-year follow-up. The rates for women who did not undergo RT were 69 percent and 49 percent, respectively. RT also improved cause-specific survival.
Korah and colleagues observed patients were statistically more likely to undergo RT if they were younger than 80 years old, received a diagnosis from 2000 to 2004 or if re-excision of the biopsy site was required for residual disease.
The researchers reported 70 percent of women in the study underwent RT after surgery; however, rates dropped over time. From 2000 to 2004, 72 percent of patients received RT. The rate decreased to 66 percent from 2005 to 2008. This decline corresponds with publication of trials that did not observe benefits in this cohort and revision of the NCCN treatment guidelines in 2005.
“The large number of patients and breast cancer-specific events in this study highlighted clinically meaningful survival advantages among patients who received radiation in conjunction with breast-conserving surgery as compared to those who received breast-conserving surgery alone, which may not have been detected in earlier studies. In advancing the care of our patients, treatment recommendations should be guided by a synthesis of the best available aggregate evidence,” Korah said in a press release.