Objective To predict the patients who can benefit from local surgery for bone-only metastatic breast cancer (bMBC). Methods Patients newly diagnosed with bMBC between 2010 and 2019 in SEER database were randomly divided into a training set and a validation set at a ratio of 7∶3. The Cox proportional hazards model was used to analyze the independent prognostic factors of overall survival in the training set, and the variables were screened and the prognostic prediction model was constructed. The concordance index (C-index), time-dependent clinical receiver operating characteristic curve and area under the curve (AUC), calibration curve and decision curve analysis (DCA) were used to evaluate the discrimination, calibration and clinical applicability of the model in the training set and validation set, respectively. The model was used to calculate the patient risk score and classify the patients into low-, medium- and high-risk groups. Survival analysis was used to compare the survival difference between surgical and non-surgical patients in different risk groups. Results A total of 2057 patients were enrolled with a median age of 45 years (interquartile range 47-62 years) and a median follow-up of 32 months (interquartile range 16-53 months). Totally 865 patients (42.1%) died. Multivariate Cox proportional hazards model analysis showed that the overall survival of patients with surgery was better than that of patients without surgery [hazard ratio=0.51, 95% confidence interval (0.43, 0.60), P<0.001]. Chemotherapy, marital status, molecular subtype, age, pathological type and histological grade were independent prognostic factors for overall survival (P<0.05), and a prognostic prediction model was constructed based on the independent prognostic factors. The C-index was 0.702 in the training set and 0.703 in the validation set. The 1-, 3-, and 5-year AUCs of the training set and validation set were 0.734, 0.727, 0.731 and 0.755, 0.737, 0.708, respectively. The calibration curve showed that the predicted survival rates of 1, 3, and 5 years in the training set and the validation set were highly consistent with the actual survival rates. DCA showed that the prediction model had certain clinical applicability in the training set and the validation set. Patients were divided into low-, medium- and high-risk subgroups according to their risk scores. The results of log-rank test showed that local surgery improved overall survival in the low-risk group (training set: P=0.013; validation set: P=0.024), but local surgery did not improve overall survival in the medium-risk group (training set: P=0.45; validation set: P=0.77) or high-risk group (training set: P=0.56; validation set: P=0.94). Conclusions Local surgery can improve the overall survival of some patients with newly diagnosed bMBC. The prognostic stratification model based on clinicopathological features can evaluate the benefit of local surgery in patients with newly diagnosed bMBC.
Objective To explore the axillary lymph node dissection (ALND) could be safely exempted in younger breast cancer patients (≤40 years of age) who receiving breast-conserving surgery combined with radiotherapy in metastasis of 1–2 sentinel lymph node (SLN) and T1–T2 stage. Methods The data of pathological diagnosis of invasive breast cancer from 2004 to 2015 in SEER database were extracted. Patients were divided into SLN biopsy group (SLNB group) and ALND group according to axillary treatment. Propensity matching score (PSM) method was used to match and equalize the clinicopathological features between two groups at 1∶1. Multivariate Cox proportional risk model was used to analyze the relationship between axillary management and breast cancer specific survival (BCSS), and stratified analysis was performed according to clinicopathological features. Results A total of 1 236 patients with a median age of 37 years (quartile: 34, 39 years) were included in the analysis, including 418 patients (33.8%) in the SLNB group and 818 patients (66.2%) in the ALND group. The median follow-up period was 82 months (quartile: 44, 121 months), and 111 cases (9.0%) died of breast cancer, including 33 cases (7.9%) in the SLNB group and 78 cases (9.5%) in the ALND group. The cumulative 5-year BCSS of the SLNB group and the ALND group were 90.8% and 93.4%, respectively, and the log-rank test showed no significant difference (χ2=0.70, P=0.401). After PSM, there were 406 cases in both the SLNB group and the ALND group. The cumulative 5-year BCSS rate in the ALND group was 4.1% higher than that in the SLNB group (94.8% vs. 90.7%). Multivariate Cox proportional hazard analysis showed that ALND could further improve BCSS rate in younger breast cancer patients [HR=0.578, 95%CI (0.335, 0.998), P=0.049]. Stratified analyses showed that ALND improved BCSS in patients diagnosed before 2012 or with a character of lymph node macrometastases, histological grade G3/4, ER negative or PR negative. Conclusions It should be cautious to consider the elimination of ALND in the stage T1–T2 younger patients receiving breast-conserving surgery combined with radiotherapy when 1–2 SLNs positive, especially in patients with high degree of malignant tumor biological behavior or high lymph node tumor burden. Further prospective trials are needed to verify the question.