Abstract: OBJECTIVE To explore the risk factors for postoperative pulmonary infection in breast cancer patients and their impact on peripheral blood cytokines. METHODS A total of 170 patients who underwent modified radical mastectomy in breast surgery department of the First Affiliated Hospital of Tianjin University of Traditional Chinese Medicine from Jan 2016 to Jul 2019 were retrospectively analyzed, the enrolled patients were divided into the infection group with 32 cases and the non-infection group with 138 cases according to the fact whether the patients had pulmonary infection within 1 month after the surgery. The features such as age, smoking history, combined chemoradiotherapy and catheter indwelling time of the patients were recorded. The levels of carbohydrate antigen 153 (CA153), CA125, tissue polypeptide specific antigen (TPS), interleukin-6 (IL-6), C-reactive protein (CRP), procalcitonin (PCT) and circulating tumor cells (CTCs) were detected after the surgery for 24 hours. Logistic regression analysis was performed for the risk factors for the postoperative pulmonary infection, and the correlation between the risk factors and the cytokines was analyzed by means of Pearson analysis. RESULTS Complication with smoking history(OR=1.755,P=0.036), chemoradiotherapy(OR=1.844,P=0.023) and catheter indwelling time(OR=1.837,P=0.033) were the risk factors for the postoperative pulmonary infection in the breast cancer patients. The levels of serum CA153, CA125, TPS, IL-6, PCT and CRP as well as the positive rate of CTCs were significantly higher in the infection group than in the non-infection group after the surgery (P＜0.05). The complication with smoking history and extension of catheter indwelling time were positively correlated with the elevation of levels of serum IL-6, CRP and PCT (P<0.05), the chemoradiotherapy was positively correlated with the elevation of levels of serum CA153, CA125, TPS, IL-6, CRP, PCT and CTCs (P<0.05). CONCLUSION Complication with smoking history, chemoradiotherapy and extension of catheter indwelling time are the risk factors for the postoperative pulmonary infection in the breast cancer patients, which may affect the changes of postoperative serum tumor markers and inflammatory factors.