| BRCA1
and BRCA2 genes found to play major role in ovarian cancer The research group that determined the BRCA1 gene plays a major role in ovarian cancer has found the same to be true for the BRCA2 gene, according to an article in the September 18th issue of the Journal of the National Cancer Institute. The findings point to the importance of developing therapies to restore normal BRCA2 and/or BRCA1 function in women with ovarian or fallopian cancer, or a related cancer known as primary peritoneal cancer. The American team examined BRCA2 dysfunction in the tumors of 92 women who had been the focus of the earlier BRCA1 study. Investigators found that 82 percent of the tumors had dysfunctional BRCA1 or BRCA2. The high incidence rate for gene dysfunction contrasts dramatically with the BRCA1 and BRCA2 dysfunction rates previously associated with ovarian cancer, said Richard Buller, M.D., Ph.D., the study's principal investigator. "As recently as two to three years ago, people thought only 5 to 10 percent of ovarian cancer cases had disrupted BRCA1 or BRCA2 function, and most of those dysfunctional genes were thought to be inherited," said Buller. "However, together the two studies show frequent BRCA2 and BRCA1 dysfunction in sporadic, or non-hereditary, ovarian cancers, not just in a portion of hereditary ovarian cancers." "With that level of dysfunction, therapies targeted toward the return of BRCA1 and BRCA2 function are very important for virtually every woman with ovarian or a related cancer," he added. The study also revealed an association between BRCA2 gene dysfunction and primary peritoneal cancer. The investigators said that to their knowledge this was the first time BRCA2 had been linked to primary peritoneal cancer. In addition, the current study is the first to use a genetic screening test called protein truncation assay to study the BRCA2 gene. The test methodology is not new, but applying it to the entire BRCA2 gene is new, Buller said. Even with the advances of the study, the true incidence of hereditary BRCA1 and BRCA2-related cancer is not completely known. "All the methods that have been used for detecting BRCA1 and BRCA2 dysfunction have limitations," Buller said. "Combining gene sequencing and protein truncation assay with other new tools and applying each method to an unselected, unbiased set of ovarian cancers would likely reveal a higher incidence rate." Buller added that one limitation of the current
study is its basis on a selected sample rather than a purely random
one. Some women in the study were specifically selected because
of what was known about their family history of ovarian cancer.
In a random sample, women would be selected among those with ovarian
cancer regardless of family history. Buller's team is now studying
a group of women with ovarian cancer who meet the criteria of a
random sample. |