Tertiary lymphoid structures in tongue cancer: Association with clinicopathological parameters, preoperative S-1 chemotherapy response, and prognosis.

Background: Tertiary lymphoid structures (TLSs) are observed in cancer-invasive sites of various organs, and show evidence of tumor-specific B and/or T cells, suggesting an active humoral antitumor response. The aim of this study was to evaluate the relationship between TLSs and prognosis in patients with tongue squamous cell carcinoma (TSCC) after preoperative S-1 chemotherapy.

Methods: Among 196 TSCC cases, 111 patients who received preoperative S-1 chemotherapy were compared to 85 patients who did not receive chemotherapy. We investigated the incidence of TLSs in both preoperative biopsy and resected specimens.

Results: TLSs were present in 24 (12%) biopsy specimens and 31 (16%) resected specimens. TLSs were associated with clinicopathologically advanced cases and positivity for lymphatic invasion. None of the cases with pStage 0 (i.e., noninvasive cancer) showed TLSs. In preoperative S-1 chemotherapy cases, TLSs were significantly more common in those treated with S-1 for more than 21 days and in those with treatment effects 0, Ia, and Ib. TLSs may not be a favorable prognostic factor by themselves but maybe a prognostic factor when combined with preoperative S-1 treatment.

Conclusion: The presence of TLSs was suggested to be a factor indicating a favorable prognosis when considering the indication for preoperative S-1 chemotherapy. The synergistic effect of S-1 by activating antitumor immunity may be associated with a better prognosis in TSCC patients with TLSs.