Tumor-infiltrating lymphocytes (TILs) appear to be strongly predictive of response to neoadjuvant chemotherapy in all molecular subtypes of breast cancer, with a survival benefit observed in HER2-positive and triple negative breast cancers, but not luminal breast cancers.1

The study, which will be presented at the 2016 San Antonio Breast Cancer Symposium, showed that increased TILs were present in 19% of 3771 analyzed tumors. The tumors with increased TILs had a pathologic complete response rate of 44% (P < .0005).

Researchers also observed increased stromal TILs in 30% of the 906 triple negative breast cancer tumors, in 19% of the 1379 HER2-positive tumors, and in 13% of the 1366 hormone receptor (HR)-positive, HER2-negative (luminal) tumors. Increased TILs were significantly associated with increased pathologic complete response rates in all 3 molecular subtypes (P < .0005).

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Univariate and multivariate analyses demonstrated that a 10% increase in TILs significantly increased the likelihood of achieving a pathologic complete response by 16% (odds ratio [OR], 1.16; P < .0005), 13% (OR, 1.13; P < .0005), and 33% (OR, 1.31; P < .0005) in triple negative breast cancers, HER2-positive tumors, and in HR-positive, HER2-negative tumors, respectively.

Increased TILs were also associated with improved disease-free survival among patients with triple negative breast cancer (P = .01) and those with HER2-positive tumors (P = .02).

In patients with luminal breast cancers, increased TILs were associated with a 10% higher risk of death per 10% increase in TILs (P = .01).

RELATED: TILs Linked to Reduced Intratumor Heterogeneity in Triple Negative Breast Cancer

The findings suggest that luminal subtype breast cancers possess a different biology of TILs. Future studies are warranted to prospectively evaluate the impact of TILs on clinical outcomes in this population and in other cancers.


  1. Denkert C, von Minckwitz G, Darb-Esfahani S, et al. Evaluation of tumor-infiltrating lymphocytes (TILs) as predictive and prognostic biomarker in different subtypes of breast cancer treated with neoadjuvant therapy – A metaanalysis of 3771 patients. Paper presented at: 2016 San Antonio Breast Cancer Symposium (SABCS); December 6-10, 2016; San Antonio, TX.