Abstract: Objective The aim of this study was to describe the changes of breast cancer treatment quality in hospitals over time,evaluate the effect of the intervention measures on the treatment quality of breast cancer that have been implemented in hospitals,and provide a scientific basis for improving breast cancer treatment quality and enhancing patient prognosis. Methods A total of 209 hospitals that participated in the study from October 1,2019 to January 31,2025 were selected.According to the intervention time,they were divided into four groups:baseline time(T₀),intervention phase Ⅰ(T₁),intervention phase Ⅱ(T₂),and intervention phase Ⅲ(T₃).The quality scores of preoperative examinations,treatment,and diagnosis of breast cancer and the comprehensive scores of treatment process indicators were calculated,respectively;According to the reported data,19 intervention hospitals were included in the intervention measures,and 190 control hospitals were matched by the propensity score matching method according to the hospital grade,ownership form,and the scores of breast cancer treatment quality dimensions of“T₀”time hospitals.Latent profile analysis(LPA)was used to classify the treatment quality of breast cancer in hospitals.Latent transition analysis(LTA)was further used to explore the impact of intervention measures on the change of treatment quality in hospitals. Results The treatment quality of breast cancer was divided into two categories by LPA analysis:“class1”was the high treatment quality group,and“class2”was the low treatment quality group.The comprehensive dimension score had improved to some extent in both groups:the score in the low treatment quality group had increased from 0.31 at the“T₀”stage to 0.36 at the“T₃”stage,while the score of the high treatment quality group had increased from 0.54 to 0.58.The change in the treatment quality of breast cancer obtained by LTA,the proportion of the potential category in“high treatment quality”increased from 35.89% at“T₀”to 96.17% of“T₃”,an increase of about 1.68 times;When the intervention was included as an explanatory variable in LTA model,the results showed that the intervention significantly influenced latent class transitions. Conclusions The study shows that intervention is an effective strategy to improve the treatment quality of breast cancer,and the intervention measures show positive effects on the inspection,treatment and diagnosis dimensions.It is suggested to improve the intervention measures in the treatment dimension to achieve the overall improvement of breast cancer treatment quality in the hospital.

Key words: breast cancer, quality of treatment, latent transition analysis, intervention effect