Objective To investigate the influencing factors of post-mastectomy pain syndrome(PMPS)in breast cancer patients who underwent modified radical mastectomy.Methods A study was conducted on 200 breast cancer patients who underwent modified radical mastectomy for at Yunxiao County Hospital of Traditional Chinese Medicine from October 2021 to December 2022.The patients were divided into PMPS and non-PMPS groups based on the presence or absence of post-mastectomy pain syndrome.Relevant influencing factors and preventive strategies were analyzed.Results Compared to the non-PMPS group,the PMPS group showed statistically significant differ-ences in tumor location,history of chronic pain before surgery,postoperative radiotherapy,and the number of lymph nodes dissected(P<0.05).Other indicators did not show significant differences between the two groups(P>0.05).The results indicated that factors such as tumor location in the upper quadrant,history of chronic pain before surgery,post-operative radiotherapy,and a higher number of lymph nodes dissected were associated with the occurrence of PMPS(P<0.05).Conclusion The occurrence of post-mastectomy pain syndrome in patients undergoing modified radical mastectomy for breast cancer is associated with multiple factors.Clinicians need to develop scientifically effective preventive strategies based on the patient's specific conditions to alleviate their pain.