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Tumor-Infiltrating Lymphocytes and Prognosis in Early-Stage Triple-Negative Breast Cancer

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Key Points

  • sTIL percentages were significantly lower with older age, larger tumor size, greater nodal involvement, and lower histologic grade.
  • Each 10% increase in sTIL level was associated with significant improvements in invasive disease–free, distant disease–free, and overall survival.

In a pooled analysis reported in the Journal of Clinical Oncology, Loi et al found that levels of stromally located tumor infiltrating lymphocytes (sTILs) are strongly prognostic in early-stage triple-negative breast cancer, with improved survival observed in patients with higher levels of sTILs after adjuvant chemotherapy.

Study Details

The study was a pooled individual patient analysis of studies assessing the prognostic value of sTILs in early-stage triple-negative breast cancer, including data from 2,148 patients from nine studies who had received anthracycline-based adjuvant therapy with or without taxanes. Patients had an average age of 50 years and 33% had node-negative disease. The primary outcome measure was invasive disease–free survival. Levels of sTILs were analyzed as a continuous variable with adjustment for clinicopathologic factors.

Associations With Outcomes

Patients had an average sTIL level of 23%, with 77% of patients having ≥ 1% sTILs. sTIL percentages were significantly lower with older age (P = .001), larger tumor size (P = .01), greater nodal involvement (P = .02), and lower histologic grade (P = .001).

In multivariate analysis, sTIL levels added significant independent prognostic information for invasive disease–free survival (likelihood ratio χ2 = 48.9, P <.001), distant disease–free survival (χ2 = 55.8, P < .001) and overall survival (χ2 = 48.5, P < .001). Each 10% increase in sTILs corresponded to a hazard ratio of 0.86 (95% confidence interval [CI] = 0.83–0.90) for invasive disease–free survival, 0.83 (95% CI = 0.78–0.87) for distant disease–free survival, and 0.83 (95% CI = 0.79–0.88) for overall survival. No significant interaction between sTILs and chemotherapy treatment was observed, with the magnitude of the prognostic effect being similar for anthracycline alone vs anthracycline-taxane regimens. In node-negative patients with sTIL levels ≥ 30% (approximately one-third of the node-negative population), 3-year rates were 92% for invasive disease–free survival, 97% for distant disease–free survival, and 99% for overall survival.

The investigators concluded, “This pooled data analysis confirms the strong prognostic role of sTILs in early-stage [triple-negative breast cancer] and excellent survival of patients with high sTILs after adjuvant chemotherapy and supports the integration of sTILs in a clinicopathologic prognostic model for patients with TNBC. This model can be found at www.tilsinbreastcancer.org.”

Sherene Loi, MD, of Peter MacCallum Cancer Centre, University of Melbourne, is the corresponding author for the Journal of Clinical Oncology article.

Disclosure: The study was supported by the Ligue Nationale Contre le Cancer and by the International Breast Cancer Study Group and participating centers. The study authors’ full disclosures can be found at jco.ascopubs.org.

The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.


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