Influence of radiotherapy on the immune function and prognosis of patients with esophageal cancer

Objective To observe the dynamic changes of the immune function in patients with esophageal cancer during the radiotherapy and also to explore its association with the clinical prognosis factors. Methods Totally 90 cases with esophageal cancer received radiotherapy in Second Affiliated Hospital of Nantong University from January 2010 to December 2013 were collected. The proportions of T-lymphocyte subsets and natural killer (NK) cells in the peripheral blood were detected by the flow cytometry from start to finish and 3 months after radiotherapy. Meanwhile, 30 cases of healthy subjects were taken as control. The changes of the immune function in the patients during the radiotherapy and the correlation between the changes and clinicopathologic features were analyzed, as well as the clinical prognostic factors were further evaluated. Results The difference of proportions of CD4+ T cells (28.23%±8.22%), CD8+ T cells (31.79%±7.61%), CD4+ /CD8+ ratio (0.93±0.34) and NK cells (11.37%±4.57%) in pre-radiotherapy patients with esophageal cancer were statistically significant (t=4.292, P=0.000; t=2.811, P=0.006; t=5.894, P=0.000; t=3.965, P=0.000) compared with control group (36.03%±9.71%, 27.26%±7.70%, 1.34±0.27, 15.31%±5.13%); but the proportions of CD3+ T cells (58.13%±9.46%) had no obvious difference (t=0.988, P=0.325) compared with control group (60.06%±8.67%). The immune function of esophageal patients in 3 months after radiotherapy such as CD3+ (59.27%±9.92%), CD4+ (30.51%±9.04%), CD8+ (29.79%±6.98%) and NK cells (10.62%±4.43%) gradually returned to the pre-radiotherapy levels (t=0.789, P=0.431; t=1.769, P=0.079; t=1.837, P=0.068; t=1.113, P=0.267). The changes of immune function (CD4+ , CD8+ , CD4+ /CD8+ ratio, NK cells) after radiotherapy were related to the bone marrow suppression (t=4.050, P=0.001; t=2.180, P=0.015; t=2.130, P=0.020; t=3.520, P=0.003) and irradiation volumes (t=5.170, P=0.000; t=3.350, P=0.026; t=8.750, P=0.000; t=2.490, P=0.043). Survival analysis showed that the patients whose immune function recovered better in 3 months after radiotherapy had a longer median survival time than those recovered bad (23 months vs. 17 months, χ2=6.820, P=0.009). Conclusion The patients of esophageal cancer are immunosuppressive before radiotherapy and will further aggravated after radiotherapy. The degree of immunosuppression is associa-ted with bone marrow suppression and irradiation volumes. The immune function of patients are recovered in 3 months after radiotherapy, and the patients whose immune function recovered better have good prognosis. Key words: Esophageal neoplasms; Radiotherapy; T-lymphocyte subsets; Natural killer cells