Tumor-infiltrating lymphocytes (TILs) have been described in various tumors, including breast cancer. In early breast cancer, the presence of TILs is associated with better outcomes and response to therapy. A review of data demonstrated the prognostic and predictive biomarker role of TILs in early breast cancer, according to researchers who looked at TILs in the neoadjuvant and adjuvant setting as well as in residual disease. The findings were published in Cancer Treatment Reviews.
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In the neoadjuvant setting, Carmen Criscitiello, MD, PhD, Istituto Europeo di Oncologia (Milano, Italy), and colleagues found that TILs represent a positive predictor for partial complete response (pCR) by identifying tumors at good outcome. The combination of TILs and pCR might help fine-tune the risk of recurrence, therefore improving treatment decisions. For patients with tumors presenting high lymphocytic infiltration, despite achieving a pCR, the researchers suggested that more aggressive therapy may not be warranted as they already have a good prognosis. However, additional therapies inducing an immune response and promoting TILs may be beneficial for patients with tumors displaying low or no lymphocytic infiltration, especially if they do not achieve pCR.
They noted that the importance of TILs appears to be particularly evident in the most aggressive subtypes, namely human epidermal growth factor receptor 2-positive breast cancer and triple negative breast cancer (TNBC). For example, they highlighted a retrospective study of 304 patients with TNBC and residual disease after neoadjuvant chemotherapy. The findings showed that TILs at surgery were associated with better prognosis, especially among patients with large tumor burden.
Studies have shown that TILs have been associated with improved survival endpoints in the adjuvant setting. For this reason, the researchers said TILs might be integrated as an additional risk factor to consider in the decision-making process. Because immunotherapy is being studied more often in patients with breast cancer, it will be important for clinicians to understand which tumors derive the greatest benefit from additional therapy with immune-modulating agents. In this context, the researchers suggested that TILs might be a relevant biomarker to incorporate in future clinical trials.
“Data collected so far are robust enough to assert that TILs are a promising potential prognostic and predictive biomarker in early breast cancer. This parameter should be easily integrated in daily routine diagnostics in which most techniques are based on FFPE [formalin-fixed paraffin embedded] tissue,” they concluded. “It is time-saving and inexpensive and, therefore, also suitable for evaluation of large study cohorts. Furthermore, it might be an added value in daily clinical practice, particularly now that recommendations have been published to make this evaluation standardized and reproducible.”—Eileen Koutnik-Fotopoulos
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