Advanced breast screening using polygenic risk score

Breast cancer screening involves conducting tests to find breast cancer in its earliest stages. In this article, consultant oncoplastic breast surgeon Mr Alexander Leeper describes a new approach to breast cancer screening using the polygenic risk score.

Breast screening is an important process for preventing the progression of breast cancer and catching the signs of conditions that can lead to the development of breast cancer.

The most typical breast screening test is the mammogram, which is a specialised X-ray of the breast. Other methods include breast MRI and clinical breast exams, where a clinician feels for abnormalities and lumps in the chest area.

However, the downfall of the traditional screening tests is that they can sometimes lead to false positives, meaning that patients who are very low risk get overdiagnosed. Additionally, not all patients who are at high risk of breast cancer know of their risk, and they may not attend screenings or get tested until breast cancer has developed significantly. This is why the polygenic risk score can help augment accurate results of breast screenings.  

What is a polygenic risk score?

The polygenic risk score (PRS) is a manner of assessing the likelihood of developing a disease, based on the genetic changes that typically are related to the disease.

To obtain the PRS, the patient’s DNA is analysed, specifically a part of the DNA called single nucleotide polymorphism (SNP), which is a genetic variation. In each individual, the combination of SNPs is unique, which can help doctors predict the patient’s susceptibility to developing breast cancer. The more combinations of SNPs, the higher the chance of abnormal cell mutation leading to breast cancer.

How can a polygenic risk score further breast cancer screening?

The PRS is not meant to be used to replace the mammogram and other screening tests but is to be used in conjunction with them to avoid mis- or underdiagnoses. When a high PRS is considered alongside mammographic results of dense breast tissue, doctors can assess with higher accuracy the patient’s risk for developing breast cancer.

With that information, high-risk patients can start with preventative therapies sooner, like taking tamoxifen and raloxifene, or for those with a very high risk, they can undergo risk-reducing breast surgery where excess and at-risk breast tissue is removed. On the other hand, patients who are low-risk need not undergo as frequent screenings, which can further cut down on medical costs for both clinics and patients.

To learn more about polygenic risk scores and breast screenings, consult Mr Leeper on Top Doctors.