Racial/Ethnic and Socioeconomic Differences in Colorectal and Breast Cancer Treatment Quality: The Role of Physician-level Variations in Care.
Despite a large body of research showing racial/ethnic and socioeconomic disparities in cancer treatment quality, the relative role of physician-level variations in care is unclear.



To examine the effect of physicians on disparities in breast and colorectal cancer care.



Linked SEER Medicare data were used to identify Medicare beneficiaries diagnosed with colorectal and breast cancer during 1995-2007 and their treating physicians.



We identified treating physicians from Medicare claims data. We measured the use of NIH guideline-recommended therapies from SEER and Medicare claims data, and used logistic models to examine the relationship between race/ethnicity, socioeconomic status, and cancer quality of care. We used physician fixed effects to account for between-physician variations in treatment.



Minority and low socioeconomic status beneficiaries with breast and colorectal cancer were less likely to receive any recommended treatments as compared with whites. Overall, between-physician variation explained <20% of the total variation in quality of care. After accounting for between-physician differences, median household income explained 14.3%, 18.4%, and 13.2% of the variation in use of breast-conserving surgery, chemotherapy, and radiation for breast cancer, and 13.7%, 12.9%, and 12.6% of the within-physician variation in use of colorectal surgery, chemotherapy, and radiation for colorectal cancer, whereas race and ethnicity explained <2% of the within-physician variation in cancer care.



Between-physician variations partially explain racial disparities in cancer care. Residual within-physician disparities may be due to differences in patient-provider communication, patient preferences and treatment adherence, or unmeasured clinical severity.
*Division of General Internal Medicine and Health Services Research, David Geffen School of Medicine, Los Angeles, CA †Division of Population Sciences, Dana Farber Cancer Institute and the Harvard Medical School, Boston, MA.
Ioana
I
Popescu
Deborah
D
Schrag
Alfonso
A
Ang
Mitchell
M
Wong
D000368:Aged; D000369:Aged, 80 and over; D001943:Breast Neoplasms / Q000208:ethnology*; D018567:Breast Neoplasms, Male; D015179:Colorectal Neoplasms / Q000208:ethnology*; D016208:Databases, Factual; D005260:Female; D054625:Healthcare Disparities / Q000208:ethnology*; D006801:Humans; D016015:Logistic Models; D008297:Male; D006278:Medicare; D011787:Quality of Health Care; D018426:SEER Program; D012923:Social Class; D014481:United States