Survival Analysis And Prognostic Factors Of Palliative Radiotherapy In Patients With Metastatic Colorectal Cancer

PART I Survival analysis of palliative radiotherapy combined with systemic therapy in patients with metastatic colorectal cancerObjective: To investigate whether palliative radiotherapy can further improve overall survival(OS)of patients with metastatic colorectal cancer(m CRC)on the basis of systemic therapy,and to analyze its potential survival prognostic factors.Methods: To collect the date of 488 patients with metastatic colorectal cancer(m CRC)confirmed by pathology in the oncology department of our Hospital.They were divided into two groups: simple systemic treatment group(333 cases,no-RT group)and the systemic treatment combined with radiotherapy(155 cases,RT group).Propensity score matching method(Propensity matched scoring method,PSM)was used to match 144 pairs of 288 patients.The primary endpoint was overall survival(OS),defined as patients with stage IV colorectal cancer from the date of diagnosis to the date of death from any cause or up to the date of their last follow-up.Kaplan-Meier was used for OS survival analysis,log-rank test was used to compare survival outcomes of each group,and Cox proportional risk model was used for multivariate analysis.P<0.05 was considered statistically significant.Results: We used the following baseline characteristics as matching factors : age,gender,status of surgery,T stage,N stage,time to metastases and status of KRAS.The subjects were matched on a one-to-one basis and a total of 288 patients were successfully matched in 144 pairs.After matching,the survival results of the two treatment methods were compared and we found that the median OS of the RT group and the no-RT group was 50.8 months vs 32.2 months,the difference between the two groups was statistically significant(P=0.003).The OS rates of the RT group for 1 year and 2 years were 95.9%,76.7%,while the 1 year,2 years OS rates of the no-RT group were 84.2% and 60.0%.The subgroup analysis indicated that the OS of the RT group was significantly better than that of the no-RT group in patients with synchronous metastases,patients who did not receive local treatment of metastasis except radiotherapy and patients who did not receive targeted therapy.Multivariate analysis before and after matching showed that palliative radiotherapy was associated with the favorable prognosis of patients with m CRC.Conclusion: We definitely demonstrated that palliative radiotherapy as a treatment for m CRC can improve OS in patients with m CRC combined with systemic treatment.PART Ⅱ Prognosis analysis of patients with metastatic colorectal cancer who received palliative radiotherapyObjective: The study aimed to investigate the clinical characteristics,survival and prognostic factors of patients with metastatic colorectal cancer who received radiotherapy on the basis of the first part of the study.Methods: From December 2014 to October 2019,155 patients with primary metastatic colorectal cancer were confirmed by pathological tissue in the oncology department of our hospital,in whom 137 met the inclusion criteria.All patients received palliative radiotherapy(RT).Kaplan-Meier was used for OS survival analysis and univariate survival analysis.The log-rank method is used to verify differences.Cox regression model was used for multivariate analysis.Results: The median OS of 137 patients with metastatic colorectal cancer was 50.3 months,and the 1-year and 2-years OS rates were 94.7% and 72.7% respectively.Univariate analysis showed that left colorectal,only one organ transferred before RT,the site of RT for liver and lung,systemic therapy before RT,all metastases are treated with RT and the time interval was more than 10 months from diagnosis to RT were the prognostic factors for patients with m CRC who received palliative radiotherapy,further multivariable analysis showed that local treatment(including surgery,ablation and intervention)of metastasis,systemic therapy before RT,the site of RT for liver and lung were independent prognostic factors of patients with m CRC who received palliative radiotherapy.Conclusion: The results of this study showed that patients with metastatic colorectal cancer could benefit from palliative radiotherapy,local treatment(including surgery,ablation and intervention)of metastasis,systemic therapy before RT,and the site of RT for liver and lung were independent prognostic factors affecting overall survival.