ORLANDO - Ovarian cancer patients with BRCA1 or BRCA2 gene mutations have better survival than do those with neither mutation, and those with the BRCA2 mutation have better survival than do those with the BRCA1 mutation, according to the findings of a large, multicenter study.
The findings confirm the results of several prior smaller studies showing a survival advantage in mutation carriers vs. nonmutation carriers, and they provide the first direct evidence that BRCA1 and BRCA2 mutations have differing effects on survival, Kelly L. Bolton reported at the annual meeting of the American Association for Cancer Research.
She and her colleagues studied 3,531 women with invasive epithelial ovarian cancer who were enrolled in one of 24 studies in the United States, Europe, Israel, and Asia, and for whom survival data were available. They excluded patients who either were known or were likely not to have received platinum-based therapy. Included were 1,178 women with BRCA1, 367 with BRCA2, and 1,986 who were BRCA negative.
The 5-year survival was 36% in those with no mutation, 46% of those with the BRCA1 mutation, and 61% of those with the BRCA2 mutation, after adjustment for stage, grade, histology, and age at diagnosis, said Ms. Bolton, a predoctoral fellow at the National Cancer Institute.
The difference in survival between the BRCA1 mutation carriers and those with no mutation was modest, although not statistically significant (hazard ratio, 0.84). However, the difference between the BRCA2 mutation carriers and both the noncarriers and the BRCA1 mutation carriers (after adjustment for age at diagnosis) did reach statistical significance (HR, 0.57 and 0.69, respectively).
Even after the exclusion of all but high-grade, advanced-stage serous cases, the survival differences persisted, Ms. Bolton reported.
A possible explanation for the differences, based on in vitro work and some retrospective trials, may lie in patients’ responses to chemotherapy; those with the BRCA2 mutation may have an improved response, but unidentified biological differences among BRCA1 carriers, BRCA2 carriers, and noncarriers could also be driving the association, she said.
The BRCA1 and BRCA2 mutation carriers in this study did not differ in regard to tumor stage, grade, or histology. Compared with noncarriers, however, BRCA1 carriers were younger and BRCA2 carriers were older at diagnosis.
Furthermore, compared with noncarriers, BRCA1 and BRCA2 carriers were more likely to present with advanced-stage disease, high-grade disease, and serous disease.
"The findings don’t have any immediate impact on clinical practice, but they do have important implications [for both] clinical prediction and also trial design, particularly for clinical trials," Ms. Bolton said, noting that although germline mutations in the BRCA1 and BRCA2 genes (which are important in DNA damage repair and have distinct yet complementary functions) are rare in the general population, they are present in 10%-15% of those with ovarian cancer.
Indeed, the findings – which "may be a very faint silver lining" for mutation carriers with a terrible disease that still has terrible survival – do speak to the possibility that women with these mutations need to be identified in the setting of ovarian cancer, as the presence of mutations will affect thinking about treatment, said Dr. Judy E. Garber, the new AACR president and director of the center for cancer genetics and prevention at the Dana-Farber Cancer Institute, Boston. Dr. Garber moderated a press briefing where Ms. Bolton discussed her findings,
Ms. Bolton had no relevant disclosures.