A new international study has uncovered a promising prognostic biomarker for patients with early-stage triple-negative breast cancer (TNBC). The findings, published in the Journal of the American Medical Association (JAMA), suggest that individuals with high levels of tumor-infiltrating lymphocytes (TILs) within their TNBC tumors may have a lower risk of recurrence and better survival rates, even without receiving chemotherapy.
TNBC is an aggressive breast cancer subtype that does not respond to drugs targeting the estrogen receptor or HER2 protein. It is more likely to spread and recur compared to other breast cancer types. The study, led by researchers from Mayo Clinic and Gustave Roussy, analyzed data from 1,966 participants with early-stage TNBC who underwent surgery and/or radiation therapy but did not receive chemotherapy.
The results showed that higher levels of TILs, which are immune system cells that can recognize and destroy cancer cells, were associated with significantly lower recurrence rates. Specifically, five years after surgery, 95% of participants with stage 1 TNBC and high TIL levels were alive, compared to 82% of those with low TIL levels.
"This is an important finding because it highlights that the abundance of TILs in breast tissue is a prognostic biomarker in people with early-stage triple-negative breast cancer, even when chemotherapy is not administered," said Roberto Leon-Ferre, M.D., the study's first author.
The researchers believe these findings could lead to the inclusion of TIL evaluation in the routine pathological assessment of early-stage TNBC, potentially informing treatment decisions and reducing the need for intensive chemotherapy regimens in patients with a favorable prognosis.
"Future studies may allow the use of this biomarker along with standard clinicopathological factors to inform treatment decisions in TNBC patients," said Sarah Flora Jonas, Ph.D., co-first author of the study.
The researchers plan to further investigate the role of TILs as a biomarker in prospective clinical trials evaluating chemotherapy selection for TNBC patients. This could be particularly beneficial in regions with limited resources, as TIL assessment only requires a visual evaluation by a pathologist, without additional costs.