Utilizing data obtained from the National Cancer Institute’s (NCI’s) Black/White Cancer Survival Study for the period from 1985 to 1986, the authors presented a new study that systematically examined multiple explanatory factors (for example, lack of mammogram) associated with differences in stage at diagnosis for breast cancer.

“There was a highly significant association between race and stage at diagnosis (P<.00005)… Factors associated with limited access to health care (health insurance [P<.01] and usual source of medical care [P<.003]), larger body mass index (P<.02), lower mammography use history (P<.004) were significantly associated with higher disease stage among Blacks only….
Simultaneous inclusion of the factors found to have a statistically significant association with disease stage at diagnosis in both Blacks and Whites into the logistic regression model yielded -adjusted odds ratios for race of 1.68 among stage III-IV cases and 1.24 among stage IIN1 cases. Three factors, nuclear grade of the tumor, having a clinical breast examination by a physician in the last 6 years, and history of patient delay, explained approximately half of the excess risk for stage III-IV disease versus stage I-IIN0 among Black women compared with White women (odds ratio reduction from 2.19 to 1.68).”

“Our findings indicate that unequal diagnostic evaluation is unlikely to be a major factor in stage assessment at diagnosis between the races, since the extent of diagnostic evaluation, in general, is comparable. Our results show that some of the factors associated with stage at diagnosis are differentially expressed in Blacks and Whites… These findings suggest that the advanced stage of breast cancer at diagnosis is related, in part, to the poorer access to health care common to socioeconomically disadvantaged populations. These observations also demonstrate the complexity of the race-stage association and indicate the need for a greater understanding of social and health care environmental issues that may impact on the design of intervention strategies in these populations.”

“These observations point to a need to formulate and test more concrete hypotheses about possible causal pathways from race to differences in stage of diagnosis, so that factors of primary importance can be identified more readily and quantified. Identifying these causal pathways is especially important for the ultimate goal of end points for interventions so that racial differences in disease stage can be reduced or eliminated.”