Genetic testing and unnecessary breast surgery in women

Family history's impact on hereditary cancer in the population.

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Genetic testing has become crucial for assessing an individual’s risk of hereditary cancers, including breast cancer. However, the accuracy of these tests and their interpretation, especially in relation to family history, can significantly impact clinical decisions.

This study aims to shed light on whether women with a family history of cancer are more likely to receive inflated risk assessments through genetic testing and consequently undergo unnecessary breast surgery.

Some women might choose to have unnecessary breast surgery to avoid cancer after being told they have a high risk based on genetic tests. However, these tests often don’t consider family history.

A recent study by the University of Exeter found that women who discover a disease-causing gene variant in BRCA1 or BRCA2 outside of a clinic setting might be told they have a 60-80% risk of breast cancer. But in reality, if they don’t have close relatives with the condition, their risk could be less than 20%.

This warning comes from research published in the Lancet journal eClinical Medicine. In the past, women who received BRCA results usually did so because they had symptoms or a family history of the disease. The risk calculations for specific BRCA variants were based on this group, which already had a high risk.

However, many people now use home DNA testing kits or receive results from genetic research, even if they have no personal connection to breast cancer. This new research, funded by the Medical Research Council, aimed to understand the risk of these BRCA variants in the general population.

In a study using data from the UK Biobank, researchers looked at over 454,000 people aged 40 to 69. They found that having a disease-causing BRCA variant on its own raised the risk of breast cancer to 18% (for BRCA2) and 23% (for BRCA1) by age 60. If you had a close relative with breast cancer, the risk increased to 24% (for BRCA2) and 45% (for BRCA1).

Dr. Leigh Jackson, the lead author from the University of Exeter Medical School, noted that more women were opting for breast cancer surgery, partly influenced by public figures like Angelina Jolie sharing their genetic test and surgery experiences. However, he emphasized that being told you have a high genetic risk can significantly affect your fear of a condition and your choices. A chance of up to 80% is very different from 20%. To make informed decisions, Dr. Jackson suggested that cancer risk discussions should consider detailed family history, not just genetics.

He added, “If you’re told you have a high genetic risk of any disease outside of a medical setting, it’s best to talk to your doctor. They can consider various factors, including family history, to assess whether further investigation is necessary.”

The study also looked at Lynch syndrome, a genetic condition that raises the risk of colon and other cancers, and found a similar pattern. The authors cautioned that widespread genetic screening for these conditions in the general population could lead to many people undergoing unnecessary scans and procedures.

Co-author Professor Caroline Wright of the University of Exeter Medical School said, “Our findings will not just apply to breast and colorectal cancer.” All risk estimates of genetic disease have primarily been based on relatively high-risk groups who attend specialist clinics, so they will not necessarily translate to the general population.

This finding has significant ramifications for population screening using genome sequencing. We need to ensure we are researching to find the accurate risk level and to be responsible in communicating risk, to avoid unnecessary fear and distress that may lead to avoidable procedures.

This study underscores the importance of accurately interpreting genetic test results, especially in individuals with a family history of hereditary cancers. Women receiving inflated risks from genetic testing are at risk of undergoing unnecessary breast surgery.

Healthcare providers should carefully consider family history when advising patients on the appropriate course of action, ensuring that surgical interventions are based on accurate risk assessments.

Journal reference:

  1. Leigh Jackson, Michael N. Weedon et al., Influence of family history on penetrance of hereditary cancers in a population setting. eClinical Medicine. DOI: 10.1016/j.eclinm.2023.102159.

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