Survival differences by race most
apparent in advanced stages of breast cancer
Racial differences in breast cancer survival
increase according to stage of disease, a new
study finds. Published in the September 15, 2007
issue of CANCER, a peer-reviewed journal of the
American Cancer Society, a retrospective
analysis of survival data demonstrates that
within each stage, African American women had
larger tumors and were more likely to have
disease that had spread to nearby lymph nodes.
After controlling for those clinical factors the
racial disparities in survival persisted. The
investigators say their finding that disparities
in survival increased with more advanced disease
was surprising and suggested that non-clinical
factors contributed to survival differences.
Epidemiology studies have long showed significant
racial/ethnic differences in breast cancer
survival among U.S. women. African American
women have poorer five-year survival rates, and
more advanced disease at the time of diagnosis
than white women.
Whether these disparities are due to a difference
between races in tumor biology or to
socioeconomic factors that impact healthcare
access and/or the physician-patient
relationship continues to be unclear.
One key piece of evidence is that, stage for
stage, African American women have worse
clinical outcomes than white women. However,
staging disease is complex, taking into account
tumor size and regional or distant disease
spread. Also, there can be significant
differences in survival within each stage. For
example, survival at the same stage can vary by
40 percent depending on the number of lymph
nodes with disease.
Dr. Alfred Neugut from Columbia University
Medical Center, Russell McBride from Mailman
School of Public Health and their colleagues
hypothesized that racial differences in survival
within stage could be attributed to differences
in tumor size and the number of lymph nodes with
disease between the two race groups.
Analysis of clinical and demographic
characteristics from 256,174 women with breast
cancer (21,861 African American and 234,313
white) diagnosed from 1988-2003 showed that
African American women were more likely than
white women to be diagnosed with tumors greater
than 2.0-cm and to have at least one lymph node
with disease. However, racial differences in
lymph node involvement were apparent only in
tumors smaller than 3.0 cm.
After adjusting for tumor size and lymph node
status as well as other known factors, such as
age, African American women were still more
likely to die from their disease. The mortality
rate among African American women was calculated
to be up to 56 percent higher than whites.
This study confirms “statistically significant
differences within stage between black and white
women in tumor size and nodal involvement.”
However, the authors conclude, “these
differences are not clinically important with
respect to survival over and above the standard
AJCC stage categories.”
The study also found that as stage of disease at
diagnosis increases, so too does the gap in
mortality between African American and white
women. The authors postulate that “the factors
that prevent black women from receiving the same
quality of care as white women may be
exacerbated by the more complex treatment
regimens used for more advanced breast cancer.”
