About 70% of breast cancers are hormone-sensitive. However, this group is very heterogeneous from a clinical and biological point of view. In the past few years, the incorporation of second generation genomic tests into clinical practice has allowed the identification of a group of patients at low risk of relapse who do not need chemotherapy and another group at high risk, who do need it. In contrast, the benefit of chemotherapy in the group of intermediate-risk patients is uncertain.
The team led by Dr. Aleix Prat has analyzed the genomic data of more than 2,000 tumors of patients with breast cancer treated in 8 clinical trials. With these molecular data and complex bioinformatic tools they have discovered and validated a new third generation genomic test that is able to better detect the sensitivity of tumors to chemotherapy treatment than current second generation tests. This new test is based on the analysis of the data produced by the second generation genomic test known as PAM50. "The second-generation genomic tests that we are currently using can predict the survival of patients with hormone-sensitive breast cancer and this information is useful for making decisions about the need to indicate chemotherapy. With this new third generation test we have taken a step forward and now we can directly predict the benefit to be gained from chemotherapy, as well as with the hormone therapy”, explains Dr. Prat.
In addition, this test is especially useful in a subgroup of breast cancer patients who have an intermediate risk of relapse during the first 10 years of follow-up and who account for one-third of patients in which the second-generation test is used. "This is the most difficult group to treat because, at the moment, the most suitable therapeutic option has not been established. In thiss context, the test helps us to choose one treatment, the other, or both", explains Dr. Prat. "This new genomic test brings us closer to personalized or precision medicine; that is, it provides more detailed information about the benefits and risks of chemotherapy and hormone therapy. This information also helps to empower patients in making decisions about their treatment”, he concludes. The new test will be implemented in clinical practice at Hospital Clínic of Barcelona before the end of this year.