The relationship between lymphocyte infiltrates (LIs) and breast cancer outcome remains
controversial. We performed this meta-analysis to elucidate the relationship.
A literature search identified 21 eligible studies.
16,097 patients were included. Multivariate analyses data for patients with unspecified receptors status showed
that rich LIs expression was associated with 52% (hazard ratio [HR] = 0.48; 95% confidence interval [CI], 0.30-0.77), and
29% (HR = 0.71; 95% CI, 0.63-0.80) reduction in the risk of relapse and death, respectively. In the neoadjuvant setting,
rich LIs predicted a 28% increase in complete pathological response rate. The prognostic and predictive utility of rich LIs
was restricted to patients with estrogen receptor negative (ER-) or triple negative disease. Only rich CD8+ T cells tumors
demonstrated clinical utility.
LIs significantly correlated to outcome predominantly in ER- tumors. Integrating immunotherapy with
conventional therapy may warrant future research in breast cancer.