The analytic sample consisted of 201,305 Medicare beneficiaries, of whom 18,008 (8.9%) were African American (). A higher proportion of African Americans attended an NCI Cancer Center than Caucasians (11.1% vs. 6.9%). Some of the notable characteristics which differed between African Americans and Caucasians who attended NCI Cancer Centers included: 1. predominance of primary care prior to diagnosis (NCI Cancer Center attendees: Caucasian, 40.5%, African American, 49.6%; non-NCI Cancer Center attendees: Caucasian, 46.5%, African American, 55.8%), 2. number of comorbidities (5 or more comorbidities -- NCI Cancer Center attendees: Caucasian, 2.5%, African American, 3.9%; non-NCI Cancer Center attendees: Caucasian, 3.8%, African American, 6.0%), and receipt of cancer-directed surgery (NCI Cancer Center attendees: Caucasian, 60.4%, African American, 53.8%; non-NCI Cancer Center attendees: Caucasian, 58.2%, African American, 49.9%) (). These factors were included in subsequent adjusted models.
Characteristics of African-American and Caucasian Medicare Beneficiaries With an Incident Diagnosis of Breast Cancer as Recorded in the Surveillance, Epidemiology, and End Results Program From 1998 to 2002 (n=201,305)
Overall cancer-specific mortality occurred in a higher proportion of African American patients compared to Caucasian at both one and three years (one year: 18.0% vs. 14.7%, respectively; three years: 25.0% vs. 20.0%, respectively) (). These mortality differences were nearly the same for patients not attending NCI Cancer Centers. Among NCI Cancer Center attendees, no material differences in mortality was seen by race: cancer-specific mortality at one year: 12.3% (African Americans), 12.4% (Caucasians); at three years: 19.9% (African American), 20.0% (Caucasian).
Characteristics of African-American (n=18,008) and Caucasian (n=183,297) Medicare Beneficiaries With Breast, Lung, Colorectal, or Prostate Cancer at 1-Year or 3-Years After Diagnosis
To examine the observed differences in mortality by race and NCI Cancer Center attendance while accounting for covariates, we developed logistic regression models. We first compared likelihood of 1- and 3- year mortality between Caucasians and African Americans in our study population. Crude models demonstrated the expected greater odds of mortality at both one and three years for African Americans relative to Caucasians (). Higher odds for 1- and 3-year all-cause mortality among African Americans compared to Caucasians persisted, although attenuated in models adjusted for age at diagnosis, sex, travel time to the nearest NCI Cancer Center, attendance at an NCI Cancer Center, predominance of primary care prior to diagnosis, stage at diagnosis, cancer site, rurality, comorbidities, median household income for ZIP code of residence, and SEER registry of residence, higher odds (). Likelihoods of cancer-specific mortality were similar to those of all-cause mortality (). To account more fully for differing risks of mortality based on cancer site, we performed logistic regression models stratified by cancer site. Excess risk of mortality for African Americans was seen for all four cancers, with the strongest effect at three years (). (Caucasian referent – 1-year mortality: Breast:OR=1.19; 95% CI 1.03–1.37, Lung:OR=1.10; 95% CI 1.02–1.19, Colorectal:OR=1.19; 95% CI 1.08–1.31, Prostate:OR= 1.12; 95% CI 0.99–1.26. 3-year mortality: Breast:OR=1.22; 95% CI 1.10–1.36, Lung:OR=1.15; 95% CI 1.06–1.24, Colorectal:OR=1.30; 95% CI 1.20–1.41, Prostate:OR=1.18; 95% CI 1.08–1.28).
Table 3 Comparison of Crude and Adjusted Predictive Models of Mortality for African Americans Relative to Caucasians at 1 Year and 3 Years After Diagnosis Among Medicare Beneficiaries (n=201,305) With an Incident Diagnosis of Breast, Lung, Colon/Rectal, or Prostate (more ...)
Figure 1 Predictive models of 1- and 3-year cancer-specific mortality as a function of cancer site in African American Medicare beneficiaries compared to Caucasian beneficiaries with an incident diagnosis of breast, lung, colon/rectal, or prostate cancer as identified (more ...)
Based on previous evidence of a mortality benefit among NCI Cancer Center attendees at one and three years from diagnosis 17
, we sought to examine whether the benefit was observed for both African Americans and Caucasians. Stratifying our mortality models by race, NCI Cancer Center attendance was associated with a significant decrease in the likelihood of 1- and 3-year mortality for both African Americans and Caucasians, with a somewhat greater decrease for African Americans (1-year mortality – Caucasians: OR=0.77; 95% CI 0.72–0.82, African Americans: OR=0.65; 95% CI 0.55–0.79. 3-year mortality – Caucasians: OR=0.95; 95% CI 0.89–1.00, African Americans: OR=0.74; 95% CI 0.63–0.86) (). We further examined the interaction of NCI Cancer Center attendance with race by comparing mortality among African Americans and Caucasians for those patients who attended an NCI Cancer Center and those who did not (). When stratifying by NCI Cancer Center attendance, we found that the adjusted 1- and 3-year all-cause and cancer-specific mortality excess for African Americans was not evident for attendees (). Post-hoc analyses to investigate potential explanatory factors for the observed mortality differences revealed a greater likelihood for African Americans to be diagnosed at late stage and a lower likelihood to receive cancer-directed surgery (Data not shown). These differences were largely accounted for by NCI Cancer Center attendance.
Figure 2 Predictive models of 1- and 3-year cancer-specific mortality as a function of NCI Cancer Center attendance in Medicare beneficiaries with an incident diagnosis of breast, lung, colon/rectal, or prostate cancer as identified in SEER-Medicare data from (more ...)
Table 4 Predictive Models of 1-Year and 3-Year Mortality as a Function of National Cancer Center Cancer Center Attendance in African-American Medicare Beneficiaries With an Incident Diagnosis of Breast, Lung, Colon/Rectal, or Prostate Cancer as Identified in (more ...)