Guideline-concordant cancer care and survival among American Indian/Alaskan Native patients

Abstract

Background: American Indians/Alaskan Natives (AI/ANs) have the worst 5-year cancer survival of all racial/ethnic groups in the United States. Causes for this disparity are unknown. The authors of this report examined the receipt of cancer treatment among AI/AN patients compared with white patients.

Methods: This was a retrospective cohort study of 338,204 patients who were diagnosed at age ≥65 years with breast, colon, lung, or prostate cancer between 1996 and 2005 in the Surveillance, Epidemiology, and End Results-Medicare database. Nationally accepted guidelines for surgical and adjuvant therapy and surveillance were selected as metrics of optimal, guideline-concordant care. Treatment analyses compared AI/ANs with matched whites.

Results: Across cancer types, AI/ANs were less likely to receive optimal cancer treatment and were less likely to undergo surgery (P ≤ .025 for all cancers). Adjuvant therapy rates were significantly lower for AI/AN patients with breast cancer (P < .001) and colon cancer (P = .001). Rates of post-treatment surveillance also were lower among AI/ANs and were statistically significantly lower for AI/AN patients with breast cancer (P = .002) and prostate cancer (P < .001). Nonreceipt of optimal cancer treatment was associated with significantly worse survival across cancer types. Disease-specific survival for those who did not undergo surgery was significantly lower for patients with breast cancer (hazard ratio [HR], 0.62), colon cancer (HR, 0.74), prostate cancer (HR, 0.52), and lung cancer (HR, 0.36). Survival rates also were significantly lower for those patients who did not receive adjuvant therapy for breast cancer (HR, 0.56), colon cancer (HR, 0.59), or prostate cancer (HR, 0.81; all 95% confidence intervals were <1.0).

Conclusions: Fewer AI/AN patients than white patients received guideline-concordant cancer treatment across the 4 most common cancers. Efforts to explain these differences are critical to improving cancer care and survival for AI/AN patients.

Keywords: Alaskan Native; American Indian; cancer; guidelines; treatment.

Figure 1

The likelihood of receiving optimal care among American Indians/Alaskan Natives (AI/ANs) compared with whites is illustrated. Multivariate logistic regression modeling is shown for Metric 1 (surgery/primary care) and Metric 2 (adjuvant therapy) for each cancer. Covariates included race; age at diagnosis; Surveillance, Epidemiology, and End Results registry site; year of diagnosis; cancer stage; and Charlson comorbidity index. LCL indicates lower control limit; UCL, upper control limit.

Figure 2

The association between receipt of optimal care and survival is illustrated. Cox proportional hazards regression modeling was used to estimate the adjusted hazard ratios associated with receipt of Metric 1 (surgery/primary care) and Metric 2 (adjuvant therapy). The models were adjusted for race; age at diagnosis; Surveillance, Epidemiology, and End Results registry site; year of diagnosis; cancer stage; and Charlson Comorbidity Index. LCL indicates lower control limit; UCL, upper control limit.