- New research finds that some women may be getting unnecessary preventative surgeries after genetic testing.
- Certain genes, including BCRA1 and BCRA2, are associated with a higher risk of breast cancer but other factors impact risk as well.
- Family history can also increase or decrease risk of developing cancer.
Some women may be getting unnecessary surgery after learning they are at risk for breast cancer from genetic testing, new research suggests.
While certain genes, including BCRA1 and BCRA2, are associated with a higher risk of breast cancer, other factors, including family history, impact their risk, too.
Genetic tests conducted outside of a clinical setting, such as at-home direct-to-consumer (DTC) tests, often do not take family history into account and may inflate people’s risk of developing breast cancer, the study, published in the Lancet journal eClinicalMedicine Thursday, suggests.
The risk overestimation may drive some people to pursue preventative surgery, the researchers suspect.
Similar results were found among people who underwent genetic screening for colorectal cancer and other types of genetic diseases as well, per the study.
The findings highlight how important it is to work with a doctor who can look at your personal and family medical history and interpret your results.
“We would highly recommend that anyone found to have a hereditary cancer gene mutation via DTC genetic testing consult with a cancer genetics expert prior to making any medical management decisions, particularly preventative surgery,” Courtney Rowe-Teeter, MS, CGC, a senior genetic counselor with the Stanford Cancer Genetics Clinic, told Healthline.
Rowe-Teeter was not involved in the new research.
Family history significantly increases disease risk in people with variants
Researchers from the University of Exeter evaluated the health data of 454,712 individuals between the ages of 40 to 69.
The data was sourced from the UK Biobank study, which collects DNA samples along with information about personal and family disease history.
Of the group, 230 women had a BCRA1 variant, 78 of whom had a first-degree relative with breast cancer, and 611 had a BRCA2 variant, 170 of whom had a first-degree relative with breast cancer.
The research team then calculated the incidence rates to detect the penetrance, which measures the proportion of individuals with a variant that develop disease.
The research team found that testing positive for BRCA1 was associated with a 23% risk of breast cancer and BRCA2 with a 18% risk of breast cancer by age 60.
Having a close family member with breast cancer pushed the risk to 45% among those who tested positive for BRCA1 and 24% for those who tested positive for BRCA2.
According to the researchers in a press release, some DTC tests may tell people who test positive for a BCRA mutation that their risk of developing breast cancer is as high as 80% — but that figure doesn’t take into account family history.
The risk in people who have a BCRA mutation but no family history of breast cancer may actually have a risk as low as 20% in some cases
The researchers say being told you have a high genetic risk may cause some people to consider preventive steps, such as invasive breast surgery, out of fear.
“Everyone perceives risk differently, but there is certainly a difference in estimating someone’s lifetime breast cancer risk to be 80% versus 30%,” Rowe-Teeter said.
The researchers found a similar result with the Lynch variant, which increases a person’s risk of colon cancer and other cancers.
Dr. Ora Karp Gordon, Regional Director of Clinical Genetics and Genomics for Providence Southern California and Professor of Genetics at Saint John’s Cancer Institute in Santa Monica, CA, said the study has a few limitations.
The BRCA breast cancer risk estimates included in this study are lower than what’s typically quoted, the age of disease was cut off at age 60, and family history of other types of cancers were not considered, Karp Gordon, who was not involved in the study said.
For example, having a first-degree family member with ovarian cancer can increase your risk of breast cancer if you have a BCRA mutation and having a first-degree family member with uterine cancer can increase your risk of colon cancer with Lynch syndrome.
Genetic counseling is necessary with genetic testing
When evaluating a person’s overall risk of disease, it’s important to look not only at the genetic mutation but their family history and personal risk factors such as age, said Rowe-Teeter.
Genes don’t tell the full story.
“For almost all genes that lead to a cancer susceptibility in adulthood, the variable lifetime risks are clearly influenced by the burden of the family history, as well as personal risk factors like reproductive status, contraceptive use, weight and lifestyle,” said Karp Gordon.
According to Rowe-Teeter, some families may have protective genetic risk factors that lower the risk.
For example, there may be two unrelated families with the same BRCA2 mutation, however, one family may have a very strong history of breast cancer while the other has a minimal breast cancer family history, she explained.
The treatment would be likely be different for each family.
“For a BRCA2+ woman in the family with a very strong history of breast cancer who has witnessed many relatives diagnosed and treated for breast cancer, they may be more inclined to consider bilateral mastectomy,” said Rowe-Teeter.
It’s crucial to receive comprehensive individualized risk assessment and management planning when doing genetic testing, especially when you are participants in research or using a DTC test, said Karp Gordon.
To find a genetic counselor in your area, you can find options from the National Society of Genetic Counselors.
“As a consumer or participant in research, no decisions on clinical management should ever be made without first clinically confirming the research or DTC genetic results and most essentially having genetic counseling from a board-certified specialist,” Karp Gordon said.
The findings aren’t meant to discourage people from participating in genetic research or screening efforts.
Many people with a BRCA mutation may not know they are a carrier and don’t receive genetic testing.
“There is a huge unmet need in identifying those at risk for hereditary cancer and other conditions,” Karp Gordon said.
The bottom line
Some women may be getting unnecessary surgery after learning they are at risk for breast cancer from genetic testing, new research suggests. At-home genetic tests may not account for family history when determining someone’s risk of disease, causing some companies to overestimate people’s risk. This could lead people to pursue preventative surgeries, even if their actual risk is much lower.
Home Genetic Testing May Inflate Risk of Breast Cancer, Study Finds
Source: Pinoy Lang Sakalam
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