Breast cancer is one of the most commonly diagnosed and prevalent cancers among women¹ accounting for over 206,000 newly diagnosed cases and nearly 40,000 deaths in the U.S. in 2010². Treatment guidelines for non-metastatic breast cancers (e.g. the National Comprehensive Cancer Network (NCCN)) provide evidence-based recommendations from clinical trials about local definitive therapy with primary surgery, node dissection and use of radiation therapy based on stage of disease. Receipt of standard of care has been observed to vary across studies for non-clinical factors such as age, race and geographic location^3–10, suggesting a need for organizations, facilities and insurers to systematically study care patterns. The present study on non-metastatic breast cancer care was conducted from data collected in the PoC breast and prostate cancers study (PoC-BP) to report on receipt of guideline-concordant local definitive therapy (surgical treatment and radiation therapy) pooled from 7 state or regional cancer registries (Georgia, North Carolina, Kentucky, Louisiana, Wisconsin, Minnesota, and Los Angeles and San Bernardino counties in California). A unique focus of this study was to identify patient characteristics related to receipt of evidence-based local definitive management of non-metastatic breast cancer in a large all-inclusive population.

Of 9142 cases of primary breast cancer in POCBP study population, 6,505 women met the criteria of a diagnosis of stage 0 through IIIA primary breast cancer and were selected for study. In Table 1, approximately 27% of study cases were less than age 50; 38% ages 50–64 years, and 36 % ages 65 years and over. Most (72%) were white, with private health insurance (55%); treated within a CoC approved facility (51%); and classified as having at least one mild, moderate or severe more comorbidity (56%). Approximately 15% were black and 5% Hispanic; and 17% lived in a high poverty census tract.

The identification of characteristics of patients not receiving guideline recommended therapy based on national guidelines is critically important so that these disparities can be strategically addressed and all patients receive appropriate therapy. A strength of this study is its large multi-state sample size, including all adult age groups, and chart re-abstraction to increase improve data collection from smaller hospitals or freestanding centers and to improve data such as commorbidities across all reporting faciulities. Approximately 12% of women in our study were found to have non-concordant loco-regional treatment for breast cancer. From the ROC analysis, the two most common deviations from guidelines were omission of RT when the surgical approach was BCS, and lymph node dissection. In some surgical facilities, BCS is a failure-risk for omission of RT, such as facilities that lack comprehensive services or integrated referral systems for cancer services. BCS Characteristics linked to non-concordant care differed by age group, as did rates of non-concordant care. Older women (age > 65 years) were significantly more likely to have non-concordant care than younger women (17.8% vs. 9.3%) as were women who lived in more affluent census tracts. For older women, non-concordant care was associated mostly with comorbidity status and race/ethnicity; whereas for younger women the correlates were non-rural residence, being treated at a non-CoC approved surgery facility and having a small tumor at diagnosis (i.e., DCIS). The finding of more guideline compliant care among younger women in CoC facilities is interesting. In exploratory analyses we found that compared to CoC facilities, women treated in non-COC facilities were more likely to be rural, live in poverty or low-educational attainment census tracts and have a high level of comobidities. Further, Non-CoC facilities were more likely to perform mastectomies and deliver BCS not followed with RT than CoC facilities in our study. In reports on adjuvant treatment, Bickel et al¹⁹ found similar barriers for racial disparities and Wu et al¹⁰ suggested that patients treated at non-CoC facilities may face barriers to multidisciplinary oncology consultations. These patterns point to a need for greater care coordination and patient support in rural regions where patients often face multiple barriers to access or treatment adherence.

Overall, approximately 60% of adult women with early stage breast cancer received breast conserving surgery. BCS has been viewed as a preferred treatment for most women with early stage breast cancer for decades based on evidence from prospective randomized trials²⁰ but there increasing use of mastectomy^21,22 in recent years perhaps due to perceived or actuarial risk for recurrence and patient preference²³, distance or local access to RT services which may be challenging in rural locations²⁴, surgeon preference or skill, and treatment recommendations for women with BRCA positivity. Like others^21,25,26 we found that receipt of BCS varied considerably by non-clinical factors such as region (rurality), insurance status, and treatment facility type. With recent evidence of a possible survival benefit among women aged 50 years and older receiving BCS and radiotherapy versus mastectomy alone regardless of age or HR status²⁷, a better understanding of how to effectively promote appropriate use of BCS may be needed. Our finding that black women were more likely to receive BCS than white women is consistent with previous reports⁹ but is difficult to interpret without patient reports as it may depend upon clinical status (e.g. tumor stage or size), cultural and treatment access (e.g., near versus far distances), hospital size or accreditation (e.g., larger or CoC accredited facilities), urban/rural status, and health insurance status^28–31. Some studies have demonstrated no differences in surgical treatment between black and white women^32–34. The finding of more concordant care with increased area affluence in the bivariate results was not present in multivariate models after accounting for age, comorbidity and tumor status.

That approximately 81% of patients in this study treated with BCS also received RT is discouraging as apparently little progress had been made over receipt of RT from earlier time periods reported in the literature by the time of study³⁶. A study of the SEER registry data between 1983 and 1995 showed that the proportion of women receiving recommended primary therapy fell from 88% in 1983–89 to 78% by the end of 1995³⁵. This pattern may reflect emerging treatment guidelines in 2004 that endorsed the use of endocrine therapy with BCS instead of RT in patients older than 70 years with low grade, node negative, ER positive tumors < 2 cm in size,¹⁸ and gave recognition to poorer survival among older patients with breast cancer due to concomitant causes that may justify less aggressive treatment to preserve quality of life. We found that women > 65 years with moderate or severe comorbidity had only half the odds of RT than those with no comorbidity. However, women of any age who were treated at a CoC approved site for their initial breast cancer surgery were more likely to receive RT than those treated at non-approved sites. This could reflect better access to care through insurance plans³⁷ or to comprehensive care within the surgical facility location and coordination of treatment with lab tests and pathology reports. Other studies have found associations of non-clinical factors and care access, such as delays in treatment for breast cancer among black women.^38–41

Some limitations of registry data studies include potential omission of records when not available for review or missing sought. In our models assessing guideline concordance, 71% of the cases had complete data, 23% had 1 variable with missing values, 5% had 2 variables and <1% had 3 or more variables with missing values. Instead of discarding cases with missing data, multiple imputation procedures were applied but are subject to the assumption of a ‘missing at random‘ data mechanism. Further, the study data do not allow for the influence of patient choice in treatment decisions as not all DCIS patients or women with early stage <2cm ER+ cancers >70 years require radiation therapy. Another limitation is that results of this study are for the 2004 diagnosis year and thus do not reflect current use of guideline care due to recent guideline changes or trends in care. Finally, because of data quality issues in registry data we were unable to examine sentinel lymph node assessments as a separate component of care, thus we have likely underestimated care concordance.

In conclusion, we found both common and distinct patterns of underuse of standard therapies and important locoregional treatment variation for non-metastatic breast cancer for older versus younger women. Increased age and DCIS was associated with more discordant loco-regional treatment among all women. Older women with higher comorbidity levels or black race/ethnicity were the most likely to have had discordant breast cancer treatment. For younger women, living in rural locations or having surgery in a COC center reduced the odds for discordant cancer treatment. Improving access to recommended care guidelines is important so that all patients receive appropriate therapy.