Comparison Of Survivals Between Breast Conserving Therapy And Breast Reconstruction Surgery For Breast Cancer

Background and purpose: Breast-conserving surgery combined with radiotherapy is one of the standard treatment options for early breast cancer,and its safety has been recognized.However,with the update of breast cancer treatment methods and concepts,the indications for breast-conserving therapy have gradually been relaxed.Previous studies on the safety of breast-conserving therapy have mostly limited in subjects with early breast cancer,and the control groups are always mastectomy or modified mastectomy.Few studies are conducted by using real-world data and comparing with other surgical therapies.Therefore,in this study,we will use the real-world SEER database to explore the survival difference between patients who received breast-conserving therapy and breast reconstruction.Methods: First-diagnosed female breast cancer patients who had no distant metastasis and underwent breast cancer surgery from January 2010 to December 2016 in the SEER database were included in this study.Subjects were divided into groups of breast-conserving therapy(breast-conserving surgery combined with radiotherapy)and breast reconstruction therapy.Propensity score matching analysis(1:1)was used to control bias factors,including age at diagnosis,race,year of diagnosis,medical insurance,histology type,histological grade,breast cancer subtypes,tumor size,number of lymph node metastases,tumor location,chemotherapy,in two groups.Kaplan-Meier curve and univariate Cox regression analysis were used to compare the differences in breast cancer-specific survival(BCSS)and overall survival(OS)in matched patients of the two groups.Besides,subgroup analyses in patients with different lymph node status,tumor size,locations,and breast cancer types were also conducted,and propensity score matching were repeated in every subgroup.Results: Finally,111,123 patients receiving breast-conserving therapy(breast-conserving surgery combined with radiotherapy)and 33,546 patients with breast reconstruction were enrolled.After propensity score matching,56,420(28210 pairs)patients were included in and their basic characteristics were equally distributed in two groups.The median follow-up was 34 months.The univariate Cox regression showed no significant difference of BCSS(HR=1.04,95%CI: 0.93-1.16,P=0.48)and OS(HR=0.95,95%CI: 0.86-1.05,P=0.31)in breast-conserving therapy(as reference)and breast reconstruction patients.Subgroup analysis revealed that,for breast cancer patients with negative regional lymph node and tumor size of ≤5cm,breast reconstruction had a decreased BCSS,which the risk of breast cancer-specific death increased by 23% compared with breast-conserving therapy(HR=1.23,95%CI: 1.02-1.49,P=0.03),however no significant difference was found in OS.Moreover,furtherly subgroup analyses of tumor locations were conducted in patients with negative lymph nodes and tumor size of ≤5cm,and results showed that decreased BCSS of breast reconstruction were only significant in patients with tumor located in the upper outer quadrant or the central area of breast.(upper outer quadrant: HR =1.54,95%CI: 1.07-2.20,P=0.02;central area:HR=4.98,95%CI: 1,44-17.21,P=0.01),and there is no difference in OS.Subgroup analyses of breast cancer subtypes were also conducted in patients with negative lymph nodes and tumor size of ≤5cm,and results revealed that,for triple-negative breast cancers,breast reconstruction had a poor survival than breast conserving therapy,which the risk of breast cancer-specific death for whom underwent breast reconstruction increased by 45%(HR=1.45,95%CI: 1.07)-1.98,P=0.02),and risk of overall death increased by 33%(HR=1.33,95%CI: 1.00-1.76,P=0.048)compared to breast-conserving therapy,and no significant survival difference between two therapies was found in other subtypes.In subjects with positive lymph nodes or tumor size of >5 cm,there was no difference in BCSS and OS between the two groups,except for patients with Her2-enriched subtype who had a better survival for breast reconstruction(BCSS HR=0.43,95%CI: 0.22-0.85,P=0.015;OS HR=0.54,95%CI: 0.29-1.01,P=0.055).Conclusions: For breast cancer patients with negative regional lymph node and tumor size of ≤5cm,breast reconstruction surgery had a decreased BCSS than breast-conserving therapy,especially in triple-negative breast cancer(patients also had a decreased OS),or in breast cancer located in the upper outer quadrant and central area.For patients with positive lymph node or tumor size>5 cm,breast-conserving therapy had the same prognosis as breast reconstruction,except for Her2-enriched breast cancer patients who had a opposite result.