Genetic risk information enables tailored breast cancer screening

Recent results from researchers at the University of Helsinki indicate that genetic risk information can help tailor and target breast cancer screening more effectively to the women who would benefit the most.

 According to the study, genetic information facilitated the identification of a group at high risk for breast cancer. This group could benefit from initiating screening significantly earlier—by up to ten years. The results are based on more than 110,000 Finnish women of breast cancer screening age and were published in the leading journal of clinical cancer research, the Journal of Clinical Oncology.

Towards more personalized breast cancer screening

Breast cancer is the most common cancer in women, affecting around 5000 Finns each year. Breast cancer is also the most common fatal cancer in women. In Finland, all women are invited for breast cancer screening every two years, starting from the age of 50.

Cancer screenings aim to detect early-stage, latent or low-symptomatic cancers and thus ensure timely and effective treatment of the patient. The benefits and harms of national cancer screening programmes have been carefully evaluated. However, some women are diagnosed with breast cancer before the start of national cancer screening. Cancer screening can also have adverse effects, such as anxiety and further investigations prompted by false positive test results.

One way to reduce harm is to tailor screening based on individual risk. Researchers have found that the use of a comprehensive genetic risk profile would be an effective tool to do this.

The researchers defined a so-called polygenic risk score for participants, which compiles information on a number of genetic risk factors that influence breast cancer risk, and compared it with data on breast cancer screenings from the Finnish Cancer Registry.

One in ten women has a significantly higher risk of breast cancer compared to the rest of the population. Comprehensive genetic information could help identify these women. Based on our results, it would be beneficial to start their breast cancer screening almost ten years earlier than is currently the practice." says

Dr. Nina Mars, lead author of the study and group leader at the Institute for Molecular Medicine Finland (FIMM) at the University of Helsinki

Comprehensive genomic data not yet used in healthcare

In Finland, the Finnish Cancer Registry systematically collects data on breast cancer screenings. A unique feature of the published study was the combination of genetic data from the FinnGen study with data from the Cancer Registry on nearly 700 000 breast cancer screening events.

The study also investigated the association of genetic risk profile with the occurrence of breast cancer diagnoses between screenings. Women in the high-risk group were diagnosed with breast cancer significantly more often between screenings than other women. So, in addition to starting screening earlier, these women could also benefit from more frequent screening.

The results also showed that abnormal screening findings were more likely to turn out to be cancer in women with a high polygenic risk score.

"The cost-effectiveness of screening and the balance between benefits and harms could be improved through risk-tailored screening, in which the start and stop ages and screening intervals could be identified," explains Nina Mars.

"More limited genetic tests are already routinely used for genetic screening of healthy family members of young breast cancer patients. The current study shows how a comprehensive genetic risk profile would enable a risk-based, tailored breast cancer screening programme for all women. This would not only detect cancers earlier and get patients into treatment earlier, but also target screening and treatment resources more efficiently," says Samuli Ripatti, Director of the Institute for Molecular Medicine Finland (FIMM), who led the study.