IMRT Use for the Treatment of Early Stage Breast Cancer in the United States

Abstract

In 2013, ASTRO issued a Choosing Wisely recommendation (CWr) to “not routinely use intensity modulated radiotherapy (IMRT) to deliver whole breast radiotherapy as part of breast conservation therapy.” A previous study reported that 11.2% of women, age ≥66, with breast cancer received IMRT in 2005. Since Choosing Wisely addresses common treatments that are unnecessary, we hypothesized that IMRT use for breast cancer was variable among regions in United States immediately preceding the CWr. SEER records for women, age ≥66, with first primary diagnosis of Stage I/II breast cancer (2007-2012) were linked with Medicare claims (2007-2013). All women had coverage for at least 12 months before and after cancer diagnosis (or until death), lumpectomy 1 month before to 6 months after diagnosis, and RT within 6 months of lumpectomy. We evaluated receipt of IMRT versus conventional or conformal therapy within 1 year of diagnosis overall and by SEER registry (12 sites). Medicare coverage was defined as favorable when Carrier or Fiscal Intermediary Local Coverage Determinations explicitly allowed breast IMRT, neutral when IMRT was not mentioned, or unfavorable when breast IMRT was explicitly forbidden or only allowed in unusual situations. We used logistic regression to estimate the adjusted associations between demographic (age, race) or tumor characteristics (grade, laterality, diagnosis year) and receipt of IMRT. Age and diagnosis year were incorporated as continuous variables, and the remaining as categorical variables. Among 13,037 women meeting inclusion criteria, mean age was 74.4, 89% were white, 50.5% had left-sided breast cancer, and 19.8% received IMRT. Table 1 shows the proportions receiving IMRT, varying from 0% in Hawaii to 52% in Detroit. Only left-sided cancer (OR=1.62, p<0.001) was associated with receipt of IMRT. The rate of IMRT did not significantly change during 2008-2012. In analyses of individual SEER sites, IMRT use was independently associated with left-side cancer in several registries (CA, GA, IA, KY, NJ, SE, UT), and significantly decreased over time in three regions (CT, GA, SE). IMRT use for women with early stage breast cancer and Medicare fee for service coverage was 19.8% across SEER registries in 2008-2012. However, the overall usage rate remained stable preceding publication of the CWr. In GA and CT, where Medicare coverage policies changed from favorable or neutral to unfavorable, there was a rapid decrease in use. Left-sided cancer was strongly associated with IMRT—suggesting that concerns about cardiac exposure and/or specific coverage policies may drive use. Our findings suggest the need for national dialogue to align practice with the CWr and reduce the considerable variation in practice between regions.Abstract 2946; Table 1% IMRTRegistryOverallLeftRightAll202416California (CA)161913Connecticut (CT)141712Detroit (DT)525846Georgia (GA)263023Hawaii (HI)000Iowa (IA)360.5New Jersey (NJ)253119Seattle (SE)693 Open table in a new tab