Women with a genetic mutation — such as a BRCA1 or BRCA2 mutation — linked to a higher cancer risk who are diagnosed with breast cancer or ovarian cancer and receive chemotherapy treatment have the same or better survival rates as women who don’t have a genetic mutation linked to higher cancer risk, according to a study.
The research was published on Aug. 9, 2021, by the Journal of the National Cancer Institute (JNCI). Read the abstract of “Association of Genetic Testing Results with Mortality Among Women with Breast Cancer or Ovarian Cancer.”
Genetic mutations and breast cancer
Two of the most well-known genes that can mutate and raise the risk of breast cancer and ovarian cancer are BRCA1 and BRCA2. Women who inherit a mutation in either of these genes — from their mothers or fathers — have a much higher-than-average risk of developing breast and ovarian cancer.
The average woman’s risk of developing breast cancer in her lifetime is about 13%. According to the National Cancer Institute (NCI), women with a BRCA1 gene mutation have between a 55% and 72% lifetime risk of developing breast cancer, while women with a BRCA2 gene mutation have between a 45% and 69% lifetime risk of developing breast cancer.
Men with these mutations — particularly a BRCA2 gene mutation — also have an increased risk of developing breast cancer and possibly an increased risk of developing prostate cancer.
About 5% to 10% of breast cancers are thought to be hereditary, meaning the cancer is linked to mutations in genes passed from parent to child.
You are substantially more likely to have a genetic mutation linked to breast cancer if:
- your mother or blood relatives (grandmothers, sisters, aunts) on either your mother’s or father’s side of the family have been diagnosed with breast cancer before age 50
- there is both breast and ovarian cancer on the same side of the family or in a single individual
- you have a relative with triple-negative breast cancer
- there are other cancers in your family in addition to breast, such as prostate, melanoma, pancreatic, stomach, uterine, thyroid, colon, or sarcoma
- women in your family have had cancer in both breasts
- you are of Ashkenazi Jewish (Eastern European) heritage
- you are a Black woman and have been diagnosed with breast cancer at age 35 or younger
- a man in your family has had breast cancer
- there is a known breast cancer gene mutation in your family
While we know that a BRCA1 or BRCA2 mutation increases the risk of breast and ovarian cancer, we don’t know if these mutations affect cancer survival.
About the study
For this study, the researchers analyzed data from the Georgia and California Surveillance Epidemiology and End Results (SEER) database. The SEER database is a large registry of cancer cases from sources throughout the United States maintained by the National Cancer Institute of the National Institutes of Health.
Overall, the study included 26,815 women: 22,495 women diagnosed with breast cancer and 4,320 women diagnosed with ovarian cancer. The women were diagnosed with stage I to stage IV disease between 2013 and 2017. All the women received chemotherapy and had genetic testing.
Follow-up time was about 41 months.
A mutation linked to a higher risk of breast cancer or ovarian cancer was present in:
- 12.7% of women diagnosed with hormone-receptor-positive, HER2-negative breast cancer
- 9.8% of women diagnosed with HER2-positive breast cancer
- 16.8% of women diagnosed with triple-negative breast cancer
- 17.2% of women diagnosed with ovarian cancer
The researchers compared cancer-specific survival rates between the women in the study and women in the general population diagnosed with the same type of cancer who did not have a genetic mutation.
Cancer-specific survival rates means the women did not die from cancer.
The study’s results found that:
- women diagnosed with triple-negative breast cancer who had a BRCA1 or BRCA2 mutation had better survival rates than women without a genetic mutation
- women diagnosed with triple-negative breast cancer who had a genetic mutation other than BRCA1 or BRCA2 had the same survival rates as women without a genetic mutation
- women diagnosed with ovarian cancer who had a BRCA2 mutation or a mutation other than BRCA1 or BRCA2 had better survival rates than women without a genetic mutation
Overall, the researchers found that none of the genetic mutations linked to a higher risk of cancer were linked to worse cancer survival.
“This is reassuring. Patients often worry that having inherited genetic risk means they are more likely to die of their cancer. Instead, they are less likely to die,” said lead study author Allison Kurian, M.D., MSc, professor of medicine and epidemiology and population health at Stanford University School of Medicine, in a statement.
What this means for you
If you’ve been diagnosed with breast cancer or ovarian cancer and know you have a genetic mutation linked to a higher risk of either of those cancers, this study is definitely reassuring.
One notable detail in the study is that all the women received chemotherapy treatment. Earlier research has suggested that cancer in women with BRCA1 or BRCA2 mutations may be more responsive to chemotherapy. Chemotherapy works by damaging cells’ DNA. BRCA1 and BRCA2 mutations interfere with cells’ ability to repair damaged DNA, so chemotherapy is likely to be more effective.
“[S]o it makes sense that these patients might have better survival — and our study confirmed that they do,” Dr. Kurian said. “This is not surprising, but it is important to have solid evidence from a large, diverse, contemporary sample that represents the U.S. population.”
If you know you have a genetic mutation and your doctor does not recommend chemotherapy for you, it makes sense to ask why and discuss this study’s results. Together, you and your doctor can develop the best treatment plan for your unique situation.
Read more about Genetics.
Written by: Jamie DePolo, senior editor
Reviewed by: Brian Wojciechowski, M.D., medical adviser
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