Adjuvant Chemotherapy for Breast Cancer Predicted by Disease, Age, and Insurance Type, but Not by Race


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[I]t seems that race and ethnicity need not pose barriers to receipt of adjuvant chemotherapy. Such a finding is encouraging as we continue to address racial and ethnic disparities in the receipt of quality cancer care.

Breast cancer mortality has been found to be higher among black and Hispanic women than among white women, with the differences in outcome being attributed in part to more advanced disease stage and greater frequency of unfavorable tumor biology among black and Hispanic women. Studies to date have not yielded a consistent picture of potential differences in chemotherapy use by race/ethnicity.

In a study reported in Journal of Clinical Oncology, Jennifer J. Griggs, MD, MPH, and colleagues from the University of Michigan in Ann Arbor, Robert Woods Johnson Medical School in New Jersey, University of Southern California in Los Angeles, and University of California at Berkeley, found that adjuvant chemotherapy use in women with breast cancer was strongly determined by disease characteristics, as well as by age and insurance status, and that white women were not more likely to receive chemotherapy than were black or Hispanic women.1

Study Design

The study consisted of analysis of survey responses from women (N = 3,252) diagnosed with breast cancer between August 2005 and May 2007 and reported to the Detroit or Los Angeles SEER (Surveillance, Epidemiology, and End Results) registry. All eligible black patients in Los Angeles and Detroit and Hispanic patients in Los Angeles were recruited, as was a random sample of white patients.

To clarify the role of acculturation, outcomes in Hispanic women were assessed by acculturation group; acculturation was measured by the Short Acculturation Scale for Hispanics (SASH), which assesses language preference (English or Spanish) on a numbered scale. The investigators hypothesized that Hispanics with low levels of acculturation would be at higher risk for not receiving adjuvant chemotherapy.

The survey was sent to 3,133 patients and completed by 2,290 (73%). Of these, 1,403 constituted the final study population, with 458 women being excluded because they had ductal carcinoma in situ and 305 being excluded due to missing information on any of the covariates assessed in the study. There was a significant difference in proportion of women by race/ethnicity who returned a completed questionnaire (57% of black women, 61% of Hispanic women, and 69% of white women; P < .001). Response rates did not differ by age.

The study population included 673 white women, 186 low-acculturated Hispanic women, 183 high-acculturated Hispanic women, and 361 black women. As had been found in prior studies, black and Hispanic women were significantly more likely to have been diagnosed at a younger age (P = .002) and to have stage II or III disease (vs stage I, P = .001), hormone receptor–negative disease (P < .001), and higher grade histology (P < .001) compared with white women. Black women were more likely than white or Hispanic women to have two or more comorbid conditions.

Multivariate Predictors of Adjuvant Therapy

Adjuvant chemotherapy was received by 65% of black women, 71% of low-acculturated Hispanic women, 65% of high-acculturated Hispanic women, and 57% of white women (P < .001 across groups). On multivariate analysis, being Hispanic, tumor characteristics, younger age, and having health insurance other than Medicaid were predictors of receipt of adjuvant chemotherapy. Number of comorbid conditions, education level, income level, and marital status were not independently associated with receipt of chemotherapy.

Key data included the following:

Compared with white women (referent category), low-acculturated Hispanic women (odds ratio [OR] = 2.00, 95% confidence interval [CI] = 1.31–3.04) and high-acculturated Hispanic women (OR = 1.43, 95% CI = 1.03–1.98) were both significantly more likely to receive chemotherapy.  In black women, this difference was not significant.

Patients with stage II (OR = 17.3, 95% CI = 13.7–21.7) or stage III disease (OR = 52.3, 95% CI = 33.7–81.2) were significantly more likely to receive chemotherapy compared with women with stage I disease, as were estrogen receptor–negative or progesterone receptor–negative patients (OR =3.34, 95% CI = 2.51–4.44) vs hormone receptor–positive patients, and patients with histologic grade 2 (OR = 2.91, 95% CI = 2.24–3.78) or grade 3 tumors (OR = 4.39, 95% CI = 3.27–5.88) vs patients with grade 1 tumors.

For each increasing year of age, patients were significantly less likely to receive chemotherapy (OR = 0.91, 95% CI = 0.90–0.92). Nearly all patients aged 30 years or less received chemotherapy, as did more than 90% of those aged 30 to 39 years; chemotherapy was received by approximately 80% of patients in the 40 to 49 year age group, 70% of the 50 to 59 year group, 55% of the 60 to 69 year group, 35% of the 70 to 79 year group, and 30% of the 80 year or older group. The authors noted that while an association of chemotherapy with age is consistent with previous findings, the finding of reduced use in patients younger than 50 years was particularly surprising.

Compared with Medicare (referent category), patients with Medicaid were significantly less likely (OR = 0.59, 95% CI = 0.37–0.95) and patients with other insurance were significantly more likely to receive adjuvant chemotherapy (OR = 1.50, 95% CI = 1.09–2.08), whereas patients with no insurance were more likely to receive chemotherapy (OR = 1.77, 95% CI = 0.98–3.19).

Patient-reported Reasons

Among reasons for not receiving adjuvant chemotherapy reported by patients (n = 633), physician-related reasons included “physician said I did not need it” in 74% of cases and “physician did not discuss it with me” in 3%. Patient-related reasons included “physician left it up to me and I chose not to” in 16% of cases, “worried about side effects or complications” in 9%, “did not want to lose my hair” in 3%, and “would have been too much of a burden on me/my family” in 3%.

The investigators acknowledge that response bias may have played a role in study findings, since receipt of chemotherapy and the covariates assessed may have differed in the substantial and unequal proportions of women who did not respond to the survey. Further, the study could not ascertain whether the quality of chemotherapy in those receiving it was equivalent across patient subgroups.

As concluded by the investigators, “[I]t seems that race and ethnicity need not pose barriers to receipt of adjuvant chemotherapy. Such a finding is encouraging as we continue to address racial and ethnic disparities in the receipt of quality cancer care. Nonetheless, differences and disparities do exist in receipt of chemotherapy according to age [and] insurance status.… These findings identify opportunities to continue to improve the quality of breast cancer care.” ■

Disclosure: The authors of the study reported no potential conflicts of interest.

Reference

1. Griggs JJ, Hawley ST, Graff JJ, et al: Factors associated with receipt of breast cancer adjuvant chemotherapy in a diverse population-based sample. J Clin Oncol 30:3058-3064, 2012.



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