Effect Of Antibiotics On Progression-free Survival In Patients With Metastatic Rectal Cancer

Objective: To study the effects of risk factors including antibiotics on progression-free survival in patients with metastatic rectal cancer.Methods: The clinical data of 32 patients with metastatic rectal cancer who received palliative chemotherapy at the Fourth Hospital of Hebei Medical University from July 01,2013 to July 01,2019 were retrospectively analyzed.When comparing the differences of clinical characteristics and chemotherapy effects between the antibiotic group and the control group,Fisher exact test was used to analyze the enumeration data,and independent sample T test was used to analyze the measurement data.When comparing the effects of clinical characteristics and antibiotics administration on progression-free survival(PFS),the first dose of palliative chemotherapy was used as the start point,the disease progression as the endpoint event.The PFS curves was calculated by Kaplan-Meier method and compared with the Log-rank test.Multivariate regression analysis was conducted using Cox’s regression model.Results:1.There were significant differences between the control group and the antibiotic group in the chemotherapy effect(P=0.038),and the chemotherapy effect of the control group was better than that of the antibiotic group.2.Univariate and multivariate analysis of PFS: In univariate analysis of PFS,age(P=0.053),gender(P=0.492),histology(P=0.798),radiotherapy(P=0.712),targeted drug therapy(P=0.405),first-line palliative chemotherapy regimen(P=0.698),palliative surgery(P=0.665),previous radical surgery(P=0.406)and antibiotics administration within 30 days before and after the first dose of palliative chemotherapy(P=0.127)had no statistical effect on PFS in patients with metastatic rectal cancer.In multivariate analysis of PFS,variables with P<0.15 in univariate analysis were used for multivariate regression in the COX proportional hazards model.The results showed age(P=0.018)and antibiotics administration within 30 days before and after the first dose of palliative chemotherapy(P=0.028)were independent risk factors for PFS in patients with metastatic rectal cancer.Patients younger than or equal to 60 years old had a higher risk of disease progression than patients older than 60 years old(median PFS 9.83 months VS 17.63 months,HR=3.512,95%CI: 1.242-9.933).Patients who received no antibiotic administration had a lower risk of disease progression than patients with antibiotics administration within 30 days before and after the first dose of palliative chemotherapy(median PFS 13.17 months VS 9.30 months,HR=0.340,95%CI: 0.130-0.889).3.Impact of antibiotics administration on PFS in the antibiotic group: type of antibiotic(P=0.436),route of antibiotic use(P=0.763),duration of antibiotic use(P=0.122),indication for antibiotic use(P=0.475)and infection site(P=0.518)had no significant difference on PFS in patients with rectal cancer.Conclusions:1.Patients who were younger than or equal to 60 years old and antibiotics within 30 days before and after the first dose of palliative chemotherapy can reduce the progression-free survival of patients with metastatic rectal cancer.2.Antibiotic administration may affect the lifetime of patients with metastatic rectal cancer by reducing the chemotherapy effect.