Stage of Disease at Diagnosis
Stage at diagnosis is widely considered a primary determinant of ultimate disease outcome. In the US as a whole, women with localized breast cancer have a five-year relative survival of 96.8 percent, whereas women who are not diagnosed until their disease has already metastasized to distant sites have a five-year relative survival of only 22.5 percent.24 In his 2002 review published in the journal Cancer, Dr. James Dignam maintained that “the benefit obtained from effective treatments is modest compared with the predictive effect that disease stage has on prognosis.”25
As established earlier, it is widely known and accepted that in California, and in the United States overall, black breast cancer patients are more likely to be diagnosed at later stages of the disease than are white patients. There are less pronounced disparities with regard to other racial/ethnic groups, with some notable exceptions. For 1988–1997, American Indian and Alaskan Natives, for example, were diagnosed at even later stages than black women were, with a larger percentage diagnosed with distant disease.26
This repeatedly confirmed observation has led a number of researchers to examine the question of whether black and white women of the same stage have similar outcomes. In other words, does the prevailing factor of stage at diagnosis account for all or most of the disparity in mortality rates?
Examining breast cancer patients from three metropolitan areas, including San Francisco-Oakland, the National Cancer Institute's Black/White Cancer Survival Study found that after controlling for age and geographic location, the risk of dying of breast cancer was 2.2 times greater for black women than it was for white women.27 In this study, adjusting for the stage at diagnosis lowered this elevated level of risk in black women by comparison with white women (OR= 1.0) from an odds ratio of 2.2 to 1.7. Clearly, other factors are at work.
A large early study conducted with data from the American College of Surgeons in 198228 obtained information on a constellation of characteristics relating to stage at diagnosis. Expectedly, it found that black women tended to have larger tumor size, greater nodal involvement, and more estrogen receptor-negative breast cancers. Even after taking into account stage, age, and tumor characteristics, outcomes for white women were significantly better. Race was determined to be an independent prognostic factor. Using data from the Black/White Cancer Survival Study group, Hunter et al. systematically examined “multiple explanatory factors” associated with breast cancer staging differences, and found the associated factors to be access to health care, lack of mammograms, and increased body mass index (BMI).29 In this study, different factors were associated with stage at diagnosis for blacks and whites. Income was associated with stage only for white patients, perhaps expressing the relatively small numbers of blacks with higher socioeconomic status.
More recent studies have led to similar findings, and have likewise determined that while time trends over the last decades show that stage at diagnosis is improving over time, much of the improvement in breast cancer outcomes has occurred disproportionately in white women.30