Impact of guideline changes on use or omission of radiation in the elderly with early breast cancer: practice patterns at National Comprehensive Cancer Network institutions.

BACKGROUND: Breast radiation therapy (RT) is a care standard after breast-conservation surgery that improves local control and survival in women. In 2004, a phase III trial demonstrated radiation after breast-conservation surgery provided no survival and limited local control benefit to women aged 70 years and older with stage I, estrogen receptor-positive cancers who receive endocrine therapy. This led to breast-conservation surgery and endocrine therapy alone being incorporated as a category I option in the National Comprehensive Cancer Network (NCCN) Guidelines for older women in 2004. We examined factors associated with change in radiation use in elderly patients at 13 NCCN centers. STUDY
DESIGN: We identified women treated at NCCN centers meeting age and stage criteria during 2000 to 2009. Factors considered a priori potentially associated with RT use were evaluated in univariate and multivariable models, including year of diagnosis, tumor and patient characteristics, axillary surgery, and treating institution. Date of diagnosis was classified as 2000 to 2004 vs 2005 to 2009, reflecting when guidelines changed.
RESULTS: Among 1,292 eligible cases, 78% received RT. In multivariable analysis, diagnosis after 2004 (p = 0.0003), older age (p < 0.0001), higher comorbidity score (p = 0.0006), smaller tumors (p = 0.0146), and omission of axillary surgery (p < 0.0001) predicted RT omission. Ninety-four percent of women aged 70 to 74 years received RT in 2000, compared with 88% in 2009. For the same times and age 80 years and older, RT use was 80% vs 41%. Finally, RT use was associated with treating institution (p < 0.0001).
CONCLUSIONS: After guideline changes for RT use in older women, NCCN centers demonstrated wide variation in implementing change. This suggests other factors are also influencing guideline uptake.