Chemotherapy-induced apoptosis of lymphocytes in esophageal cancer worsensoutcome

Background/Aims: Chemotherapy has been shown to induce apoptosis in esophag eal cancer. However, no windows of opportunity exist to selectively kill tu mor cells without killing host cells. Due to the concern that tumor-infiltr ating lymphocytes may be killed by chemotherapy, we examined the significan ce of the effect of treatment on the density of tumor-infiltrating lymphocy tes and apoptosis in the tumor itself and in the tumorinfiltrating lymphocy tes. Methodology: In 93 patients with esophageal cancer including 50 with neoadj uvant chemotherapy, esophagectomy specimens were examined for density of tu mor-infiltrating lymphocytes and for apoptosis in both tumor cells and tumo r-infiltrating lymphocytes. Results: Apoptotic index was increased by neoadjuvant chemotherapy only in tumor-infiltrating lymphocytes, apoptotic index was greater than or equal t o 4 only in chemotherapy patients. The density of tumor infiltrating lympho cytes was a significant positive prognostic factor in chemotherapy and non- chemotherapy groups, and the high apoptotic index in tumor-infiltrating lym phocytes was an independent negative prognostic factor in the chemotherapy group. Conclusions: Apoptosis in tumor-infiltrating lymphocytes was induced by che motherapy in some patients in association with a poor prognosis. Unexpected ly, chemotherapy did not increase apoptosis in tumor cells. Both findings s uggest a need for improved regimes and individualized treatment.