Correlative Research To Endocrine Therapy For Breast Cancer With Estrogen Receptor Or Progesterone Receptor Positive

BackgroundBreast cancer is the most common malignant tumor worldwide and the most common malignancy in women.Estrogen receptors and progesterone receptors can be used as one of the important indicators for the pathological classification of breast cancer,and if the hormone receptors are positive,endocrine therapy can be chosen as a treatment.The more common clinical endocrine therapeutic agents are estrogen receptor binding agents and aromatase inhibitors.Tamoxifen represents estrogen receptor binding agents,and letrozole is one of the non-steroidal inhibitors of the aromatase inhibitors.The goal of this study is to compare the 5-year DFS of hormone receptor mono-positive HER2-negative postmenopausal breast cancer patients treated with different endocrine therapeutic agents（letrozole or tamoxifen）in order to better understand the efficacy of endocrine therapy for hormone receptor mono-positive breast cancer and to summarize the patterns,in order to improve the precision and individualized treatment of breast cancer.MethodsFifty-five patients with hormone receptor mono-positive HER2-negative primary malignant tumors of the breast who underwent surgical treatment at the China-Japan Union Hospital of Jilin University from January 2010 to December 2016 were established as study population,the clinicopathological characteristics of each patient were clarified,and the survival prognosis of the patients was followed up until December 2021,and systemic treatment for breast cancer is applied to all patients.Fifty-five patients were assigned to two groups according to the applied endocrine drugs:letrozole group and tamoxifen group.ER-positive/PR-negative and ER-negative/PR-positive groups consisted of 55 patients with different ER and PR expression status.The clinicopathological characteristics（including age,BMI,lymph node status,tumor diameter,Ki-67,etc.）,efficacy and common adverse reactions of different endocrine therapeutic agents in patients with hormone receptor mono-positive HER2-negative primary malignant tumors of the breast were compared between two subgroups of patients separately to understand the efficacy and common adverse reactions of different endocrine therapeutic agents in patients with hormone receptor mono-positive HER2-negative primary malignant tumors of the breast.ResultsAmong the 55 patients,they were grouped according to the different endocrine drugs applied,20（36.4%）in the letrozole group and 35（63.6%）in the tamoxifen group.There were no statistical differences between the two groups in terms of age,BMI,tumor diameter,axillary lymph node status,Ki-67,adjuvant chemotherapy,radiotherapy and molecular typing.The 5-year DFS was90.0%and 65.7%in the letrozole and tamoxifen groups,respectively.The 5-year DFS in the letrozole group compared with the 5-year DFS in the tamoxifen group:the log-rank test result was X~2=3.927,P=0.048.All patients were categorized according to their ER and PR expression status,with 27（49.1%of the total）in the ER-positive/PR-negative group and 28（50.9%）in the ER-negative/PR-positive group.In terms of age,BMI,tumor diameter,axillary lymph node status,Ki-67,adjuvant chemotherapy,radiotherapy and endocrine medication,there were no statistical differences between the two groups.The 5-year DFS of patients in the ER-positive/PR-negative and ER-negative/PR-positive groups was analyzed by the Kaplan-meier method.The results showed that the 5-year DFS of ER-positive/PR-negative group was 88.9%and the 5-year DFS of ER-negative/PR-positive group was 60.7%.5-year DFS of the ER-positive/PR-negative group compared with that of the ER-negative/PR-positive group:Log-rank test results were X~2=6.140,P=0.013.The letrozole group was more likely to have musculoskeletal disorders（including bone pain and osteoporosis）than the tamoxifen group,and the tamoxifen group was more likely to have vaginal bleeding or vaginal discharge than the letrozole group.As for other adverse reactions,there were no significant differences between the letrozole group and the tamoxifen group.Conclusions1.Letrozole is more effective than tamoxifen in patients with hormone receptor mono-positive HER2-negative primary malignant tumors of the breast.2.Prognosis of patients with ER-positive/PR-negative phenotype is better than those patients with ER-negative/PR-positive phenotype in hormone receptor mono-positive HER2-negative primary malignant tumors of the breast.3.Adverse reactions of letrozole are mostly seen in musculoskeletal disorders,while those of tamoxifen are mostly seen in vaginal bleeding or vaginal discharge.