Research presented recently at the Society of
Gynecologic Oncologists (SGO) annual meeting found that survival
rates of African-American women with advanced-stage endometrial
cancers are significantly worse than those of Caucasian women. The
median survival of African-Americans was 1 year, compared with 2½
years for Caucasians.
The study reviewed snap frozen-tissue samples or paraffin blocks of
140 women (78 Caucasian, 62 African-American) who underwent
hysterectomy for endometrial adenocarcinoma between 1975 and 1997.
The research was conducted by Andrew Berchuck, MD, G. Larry Maxwell,
MD, Angeles A. Alvarez, MD, and Richard K. Dodge, PhD, from Duke
University Medical Center; and John I. Risinger, PhD, and J. Carl
Barrett, PhD, from the National Institute of Environmental Health Sciences.
Although African-American women have a lower incidence of endometrial
cancer (14.6 per 100,000 population) than do Caucasian women (22.2
per 100,000), they have a significantly higher disease-related
mortality. In a 1989-1994 review by the National Cancer Institute
(NCI), the 5-year survival rate for all stages was 86% for Caucasian
women vs only 54% for African-American women.
Although survival of African Americans is relatively poor for several
types of cancer, the racial disparity is greatest for endometrial
cancer, as seen in the Surveillance, Epidemiology and End Results
(SEER) registry of the NCI. This disparity is attributable, in part,
to the fact that African-American women, more often than their
Caucasian counterparts, present with metastatic disease, thus
significantly worsening their survival rates.
Differences in Molecular Pathogenesis
In a prior study by the Duke group, there was no racial disparity in
the time from the onset of abnormal uterine bleeding to the diagnosis
of endometrial cancer or in the intensity of treatment. This
suggested that underlying racial differences in the molecular
pathogenesis of the cancers might contribute to the disparity in
survival. Consistent with this theory, it was subsequently shown that
the racial disparity in survival can be attributed, in part, to a
higher frequency in the overexpression of the p53 tumor-suppressor
gene in African-Americansa molecular alteration associated with
high-risk, nonendometrioid histology and poor prognosis.
Both mutation of the PTEN tumor suppressor gene and
microsatellite instability are molecular changes that have been
associated with favorable outcome in endometrial cancers. We needed
to get a better understanding of any racial differences in the
frequency of these molecular alterations to determine whether this
contributes to the racial disparity in survival. Hopefully, if we can
understand the molecular basis for the racial disparity in survival,
we can use this knowledge to decrease the high mortality rate of
African-American women with endometrial cancer, said the
studys senior author Andrew Berchuck, md, professor, Department
of Obstetrics and Gynecology, Duke University.
The study found no racial difference in the frequency of
microsatellite instability in endometrial cancers, but mutations in
the PTEN tumor-suppressor gene, which are associated with more
favorable survival, were four times more common in endometrial
cancers of Caucasians (22%) than in cancers of African-Americans
(5%). This finding suggests that there are racial differences in the
molecular pathways that lead to the development of endometrial
cancer, and that these underlying differences in the molecular
pathology contribute to the racial disparity in survival.
Additional Study Findings