Abstract:

Objective To analyze the effects of irinotecan combined with XELOX regimen on immune status， intestinal microecology and prognostic risk in elderly patients with colorectal cancer. Methods A total of 105 elderly patients with advanced colorectal cancer admitted to Qidong People's Hospital of Jiangsu Province from October 2018 to April 2023 were included as the study objects. They were divided into control group （n=45） and observation group （n=60） according to different chemotherapy regimen. The control group was treated with XELOX regimen alone， and the observation group was treated with irinotecan combined with XELOX regimen. The short-term efficacy， changes of indexes related to immune status and intestinal microecology before and after treatment were compared between the two groups. The patients were followed up from the end of treatment. With death or recurrence and metastasis as the end event during the follow-up， 105 patients were divided into poor prognosis group （n=32） and good prognosis group （n=73）. The clinical data of the two groups were compared， and multivariate logistic regression was used to analyze the prognostic factors in elderly patients with advanced colorectal cancer. Results The total effective rate of the observation group was 53.33% （32/60）， which was higher than that of the control group （20.00%， 9/45） （χ²=12.01， P=0.001）. One week after treatment， the ratios of CD4⁺ T cells and CD4⁺/CD8⁺ in the observation group were （38.59±1.50）% and 1.81±0.20， respectively， higher than those in the control group （36.25±1.82）% and 1.59±0.15 （t=7.22， P<0.001； t=6.19， P<0.001）. The ratio of CD8⁺ T cells was （21.27±2.70）%， lower than that of the control group （22.80±2.92）% （t=2.78， P=0.007）. The numbers of Bifidobacterium， Lactobacillus and Enterococcus were （9.44±0.82）， （9.89±0.79）， （9.14±0.66） lg CFU/g， respectively， which were higher than those in the control group （8.20±0.70）， （9.05±0.72）， （8.25±0.62） lg CFU/g （t=8.16， P<0.001； t=5.60， P<0.001； t=7.02， P<0.001）. There were statistically significant differences in the proportion of smoking and drinking history （χ²=7.61， P=0.006）， the proportion of low differentiation （χ²=6.54， P=0.011）， the proportion of lymph node metastasis （χ²=5.86， P=0.016） and the level of carcinoembryonic antigen （CEA） before chemotherapy [（5.80±0.89） μg/L vs. （7.48±1.02） μg/L， t=8.51， P<0.001]， the level of carbohydrate antigen 199 （CA199） [（29.54±1.85） U/ml vs. （34.52±2.50） U/ml， t=11.36， P<0.001] in good prognosis group and poor prognosis group. Multivariate analysis showed that smoking and drinking history （OR=1.74， 95%CI： 1.53-2.15， P<0.001）， low differentiation （OR=1.80， 95%CI： 1.60-2.15， P<0.001）， lymph node metastasis （OR=1.82， 95%CI： 1.68-2.33， P<0.001）， high CEA level before chemotherapy （OR=1.81， 95%CI： 1.62-2.38， P<0.001）， high CA199 level before chemotherapy （OR=1.80， 95%CI： 1.66-2.37， P<0.001） were risk factors for the prognosis of advanced colorectal cancer in the elderly. Conclusion Irinotecan combined with XELOX regimen can effectively improve immune function and intestinal microecology in elderly patients with advanced colorectal cancer， but the risk of poor prognosis after chemotherapy is higher. Smoking and drinking history， low differentiation， lymph node metastasis， high CEA level before chemotherapy， and high CA199 level before chemotherapy are risk factors affecting the prognosis of elderly patients with advanced colorectal cancer.

Key words: Colorectal neoplasms, Irinotecan, Gastrointestinal microbiome, XELOX regimen