Real-world impact of postmastectomy radiotherapy in T1-2 breast cancer with one to three positive lymph nodes.

BACKGROUND: The utility of postmastectomy radiotherapy (PMRT) in breast cancer patients with T1-2 (tumor size ≤5 cm) and N1 (one to three lymph nodes involved) disease remains controversial. The aim of this population-based study was to investigate the effectiveness of PMRT in this patient subset in the current clinical practice. METHODS: We included T1-2N1 breast cancer patients treated with mastectomy from 2004 to 2012 using the data form the Surveillance, Epidemiology, and End Results program. The association of PMRT administration with breast cancer-specific survival was determined using multivariable Cox analysis. RESULTS: We identified 10,248 patients of this study, including 3,725 (36.3%) received PMRT and 6,523 (63.7%) patients did not receive PMRT. Use of PMRT showed increase from 2008 onward; the percentage of patients receiving PMRT was 30.6% in 2004 and was 47.1% in 2012 (P<0.001). Patients diagnosis after 2008, aged <50 years, high tumor grade, T2 stage, and ≥2 positive lymph nodes were independently related to PMRT receipt. Multivariate analysis indicated that PMRT was not related to better breast cancer-specific survival compared to those without PMRT both before (P=0.186) and after propensity score matching (P=0.137). CONCLUSIONS: In breast cancer with T1-2N1 disease, PMRT does not appear to improve survival in the era of modern systemic therapy.

Histological Tumor Type is Associated with One-Year Cause-Specific Survival in Women with Stage III-IV Epithelial Ovarian Cancer: A Surveillance, Epidemiology, and End Results (SEER) Database Population Study, 2004-2014.

BACKGROUND The prognosis of epithelial ovarian cancer (EOC) remains poor. Cause-specific survival (CSS) is an overall survival measure of cancer survival that excludes other causes of death. This retrospective population study used the Surveillance, Epidemiology, and End Results (SEER) database to evaluate prognostic factors associated with one-year CSS in women with stage III-IV EOC between 2004-2014. MATERIAL AND METHODS Data from the SEER program included a cohort of patients with stage III-IV EOC between 2004-2014. Binomial logistic regression analysis, Kaplan-Meier survival curves, and multivariate Cox proportional hazards models were used for analysis of patient outcome, including the one-year CSS. RESULTS There were 14,798 patients with stage III-IV EOC identified from SEER between 2004-2014, including 13,134 (88.8%), 892 (6.0%), 448 (3.0%), and 324 (2.2%) patients with serous, endometrioid, clear cell, and mucinous ovarian cancer, respectively. The overall one-year CSS was 91.2%. One-year CSS was 92.5%, 92.2%, 74.0%, and 62.5% in patients with serous, endometrioid, clear cell, and mucinous ovarian cancer, respectively (P<0.001). Histological tumor type was an independent prognostic factor of one-year CSS. Patients with mucinous EOC (HR, 8.807; 95% CI, 6.563-9.965; P<0.001) and clear cell EOC (HR, 4.581; 95% CI, 3.774-5.560; P<0.001) had a significantly lower one-year CSS compared with patients with endometrioid and serous EOC who had comparable one-year CSS (HR, 1.247; 95% CI, 0.978-1.590; P=0.075). CONCLUSIONS A retrospective population study of the SEER database between 2004-2014 identified that histological tumor type was associated with one-year CSS in women with stage III-IV EOC.

Omission of adjuvant radiotherapy following breast-conserving surgery for elderly women with early-stage pure mucinous breast carcinoma.

BACKGROUND: We aimed to ascertain population-based practice patterns and survival outcomes of postoperative radiotherapy following breast conserving-surgery (BCS) in elderly women (aged ≥65 years) with early-stage pure mucinous breast carcinoma (PMBC). METHODS: Patients aged ≥65 years diagnosed with T1-2N0 and hormone receptor-positive PMBC between 1990 and 2010 were identified from the Surveillance, Epidemiology, and End Results database. Binomial logistic regression, Kaplan-Meier method, Multivariate Cox proportional hazards models, and propensity score matching (PSM) were used for statistical analysis. RESULTS: We enrolled 3416 patients, including 1225 (35.9%) and 2191 (64.1%) in the no-radiotherapy and radiotherapy cohorts, respectively. The percentage of patients receiving postoperative radiotherapy following BCS was significantly lower after 2004 (59.5% between 2004 and 2010), relative to that before 2004 (71.1% between 1990 and 2003; P < 0.001). Before PSM, the 10-year breast cancer-specific survival (BCSS) rates were 98.1 and 93.2% for patients with and without postoperative radiotherapy (log-rank test, P < 0.001), respectively. In the PSM cohort, receiving postoperative radiotherapy was associated with better BCSS rates, with 10-year BCSS rates of 97.6 and 94.5% in patients with and without postoperative radiotherapy, respectively (log-rank test, P = 0.001). Multivariate Cox proportional analysis indicated that receiving postoperative radiotherapy was an independent factor associated with better BCSS before (P < 0.001) and after PSM (P = 0.001), relative to those not receiving postoperative radiotherapy. CONCLUSIONS: This study shows a decreasing utilization of postoperative radiotherapy following BCS of elderly PMBC patients over time. However, postoperative radiotherapy following BCS should be administered for elderly women with PMBC owing to independent association with better survival.

21-Gene Recurrence Score Assay Could Not Predict Benefit of Post-mastectomy Radiotherapy in T1-2 N1mic ER-Positive HER2-Negative Breast Cancer.

Introduction: It is still controversial whether post-mastectomy radiotherapy (PMRT) is necessary for women with T1-2 N1mic ER-positive HER2-negative breast cancer. The 21-gene recurrence score (RS) assay has been validated in T1-2 N1 breast cancer to be prognostic of locoregional recurrence (LRR) and overall survival (OS). This study aims to evaluate the predict value of 21-gene recurrence score assay for the benefit of PMRT in T1-2 N1mic ER-positive HER2-negative breast cancer. Methods: A population-based cohort study was performed on women with T1-2 N1mic ER-positive HER2-negative breast cancer who underwent mastectomy and were evaluated using the 21-gene RS in the Surveillance, Epidemiology, and End Results (SEER) registry between 2004 and 2015. Clinical characteristics as well as OS and breast cancer-specific survival (BCSS) were compared between patients with and without PMRT in patients with a Low-, Intermediate-, and High-RS. Multivariate COX regression analysis was performed to investigate if the 21-gene RS assay could predict benefit of PMRT in this group of breast cancer patients. Results: A total of 1571 patients met the criteria of our study and were enrolled, including 970 patients in the Low-Risk group (score <18), 508 in the Intermediate-Risk group (score 18-30), and 93 patients in the High-Risk group (score >30). In the High-Risk group, there were more patients with age ≥50 (87.0 vs. 64.3%, P = 0.040) and received chemotherapy with a borderline significance (91.3 vs. 72.9%, P = 0.066) in the PMRT subgroup than in the no PMRT subgroup. In all three groups, OS was comparable between the PMRT subgroup and the no PMRT subgroup. Furthermore, multivariate analysis did not show any OS benefit for PMRT based on the 21-gene recurrence score. Conclusion: This study showed that the 21-gene RS assay was not able to predict the benefit of PMRT for OS in women with T1-2 N1mic ER-positive HER2-negative breast cancer. However, further prospective larger sample-size trials are warranted to determine if a benefit exists.

21-gene recurrence score and adjuvant chemotherapy decisions in patients with invasive lobular breast cancer.

AIM: To determine the effect of the 21-gene recurrence score (RS) on outcome and chemotherapy decision in breast invasive lobular carcinoma (ILC). MATERIALS & METHODS: We included 6467 patients with early stage and estrogen receptor-positive ILC from the Surveillance, epidemiology, and end results database. RESULTS: A total of 9.1, 31.4, and 70.1% of patients with low-, intermediate-, and high-risk RS groups received chemotherapy, respectively. A higher RS was independently associated with poor breast cancer-specific survival, and receipt of chemotherapy was not related to better breast cancer-specific survival in low-, intermediate-, or high-risk RS groups. CONCLUSION: The 21-gene RS could impact chemotherapy decision making in early-stage ILC. However, adjuvant chemotherapy does not appear to improve outcome in high-risk RS cohort.

Clinicopathologic characteristics and clinical outcomes of pure type and mixed type of tubular carcinoma of the breast: a single-institution cohort study.

INTRODUCTION: We aimed to evaluate the clinicopathologic characteristics and clinical outcomes of the mixed type versus the pure type of tubular carcinoma (TC) of the breast in a retrospective cohort study. MATERIALS AND METHODS: Patients were categorized into the following three groups: patients with pure TC of the breast (the PTC group), patients with TC and carcinoma in situ of the breast (the TC-CIS group), and patients with TC and other invasive carcinomas of the breast (the TC-IC group). We compared the clinicopathologic characteristics and treatment outcomes of the three groups. The primary end point of this study was breast cancer-specific survival (BCSS). Secondary end points included distant metastasis-free survival (DMFS) and locoregional recurrence (LRR). RESULTS: A total of 68 patients were included in this study, including 31 patients in the PTC group, 12 in the TC-CIS group, and 25 in the TC-IC group. Our data showed that PTC and TC-CIS were more likely to be smaller in size (P=0.014) and had substantially less nodal involvement (P=0.019), compared with TC-IC. The median follow-up time was 64.3 months (range, 3.78-223.2 months) for all patients. No locoregional relapse was observed in any group during the follow-up period. The 10-year BCSS of the PTC, TC-CIS, and TC-IC groups was 100%, 100%, and 95.2%, respectively, and the 10-year DMFS was 92.3%, 100%, and 96.0%, respectively. There was no significant difference in terms of BCSS (P=0.53) or DMFS (P=0.84) between the three groups. CONCLUSION: This study indicates that both the pure type and mixed type of TC of the breast show very low LRR and distant metastasis rate and have excellent survival. The TC-IC group is likely to show good prognosis similar to the PTC group. Further clinical trials with larger sample sizes as well as molecular and genetic studies are warranted.

Patterns of Distant Metastasis Between Histological Types in Esophageal Cancer.

Introduction: Distant metastasis remains the major cause of treatment failure in esophageal cancer, though there have been few large-scale studies of the patterns of distant metastasis in different histological types. We investigated the patterns of distant metastasis in esophageal adenocarcinoma (AC) and squamous cell carcinoma (SCC) using a population-based approach. Methods: Patients with de novo stage IV esophageal cancer at diagnosis were identified using the Surveillance, Epidemiology, and End Results database. Multivariable logistic regression was performed to identify potential risk factors for site-specific distant metastasis to the distant lymph nodes, bone, liver, brain, and lung at diagnosis. Results: We identified 1,470 patients with complete data for analysis including 1,096 (74.6%) patients with AC and 374 (25.4%) patients with SCC. A total of 2,243 sites of distant metastasis were observed, the liver was the most common site of distant metastasis (727, 32.4%), followed by the distant lymph nodes (637, 28.4%), lung (459, 20.5%), bone (344, 15.3%), and brain (76, 3.4%). Multivariable logistic regression showed that compared to patients with SCC, patients with AC were more likely to have metastasis to the brain (odds ratio [OR] 3.026, 95% confidence interval [CI] 1.441-6.357, p = 0.003) and liver (OR 1.848, 95% CI 1.394-2.451, p < 0.001), and less likely to have metastasis to the lung (OR 0.404, 95% CI 0.316-0.516, p < 0.001). Histological type had no effect on metastasis to the distant lymph nodes or bone. Conclusions: Patients with esophageal AC are more likely to present with liver and brain metastases, and less likely to present with lung metastasis than patients with esophageal SCC.

Tubular carcinomas of the breast: an epidemiologic study.

AIM: We explored the clinicopathologic characteristics, prognostic factors and outcomes in tubular carcinoma (TC) of the breast. METHODS: We retrospectively assessed 8091 TC patients using the SEER database from 2000 to 2013. RESULTS: Most patients were non-Hispanic white, well-differentiated disease, tumor size ≤2 cm, node-negative, nonmetastatic, hormone receptor-positive and HER2-negative status. The 10-year breast cancer-specific survival and overall survival were 98.1 and 82.0%, respectively. Multivariate analysis indicated that age, ethnicity, surgery procedures, radiotherapy and chemotherapy were independent predictors affecting survival outcomes. There was comparable breast cancer-specific survival between surgery and nonsurgery groups. CONCLUSION: The patients with TC has excellent survival outcomes, which may in part be due to the favorable tumor characteristics.

Long-term survival effect of the interval between mastectomy and radiotherapy in locally advanced breast cancer.

INTRODUCTION: The timing of postmastectomy radiotherapy (PMRT) may influence locoregional recurrence and survival outcomes. In this study, we assessed the long-term survival effect of the interval between surgery and PMRT in locally advanced breast cancer treated with mastectomy and adjuvant chemotherapy. METHODS: In this retrospective study, we included women with locally advanced breast cancer who underwent adjuvant chemotherapy and PMRT after mastectomy between 1999 and 2007. Based on the interval between surgery and PMRT, the patients were classified into three groups: Group 1 (≤4 vs >4 months), Group 2 (≤5 vs >5 months), and Group 3 (≤6 vs >6 months). Univariate and multivariate regression analyses were performed to determine the prognostic factors of survival outcomes. RESULTS: A total of 340 women were included in this study, and the median follow-up duration was 79.8 months. The median surgery-PMRT interval was 5 months. The surgery-PMRT interval including Group 1, Group 2, and Group 3 was not significantly associated with locoregional recurrence-free survival, distant metastasis-free survival, disease-free survival, and overall survival. In addition, in the subgroup analysis of the effect of surgery-PMRT interval on survival outcomes according to various clinicopathologic factors, the surgery-PMRT interval was also not associated with survival outcomes in different age groups, tumor stage, and breast cancer subtypes. CONCLUSION: Our findings suggest that the delay in the start of PMRT in locally advanced breast cancer does not increase the likelihood of locoregional recurrence, distant metastasis, and death.

Omission of Postoperative Radiotherapy in Women Aged 65 Years or Older With Tubular Carcinoma of the Breast After Breast-Conserving Surgery.

INTRODUCTION: To investigate the temporal trends of postoperative radiotherapy (RT) administration and the effects of omitting postoperative RT on breast cancer-specific survival (BCSS) in women aged ≥65 years with tubular carcinoma (TC) of the breast who received breast-conserving surgery (BCS). METHODS: We included women aged ≥65 years with non-metastatic TC of the breast who underwent BCS between 2000 and 2013 using the Surveillance, Epidemiology, and End Results database. Statistical analyses were performed using chi-square tests, Kaplan-Meier analyses, Cox proportional hazards models, and a 1:1 propensity score matching (PSM). RESULTS: Before PSM, a total of 1,475 patients with tumor size ≤2 cm, node-negative disease, and estrogen receptor-positive disease were identified, including 927 (62.8%) underwent postoperative RT and 548 (37.2%) had postoperative omission of RT. The administration of postoperative RT steadily declined over the study period. Patients with younger age, larger tumor size, and other race/ethnicity were more likely to receive postoperative RT. The median follow-up duration was 85.0 months, the 5- and 10-year BCSS rates were 98.7 and 97.9%, respectively. The median BCSS was 161.9 and 165.0 months for patients with and without postoperative RT, respectively, and the corresponding 5-year BCSS rates were 98.5 and 98.8%, respectively (p = 0.134). Prognostic analysis indicated that postoperative RT was not associated with improved BCSS rates compared with RT omission (p = 0.134). After PSM, a total of 431 complete pairs were generated. In the matched population, the 5-year BCSS rates were 98.6 and 98.4% in non-postoperative RT and postoperative RT groups, respectively (p = 0.858). The univariate analyses also confirmed that the administration of postoperative RT was not associated with better BCSS (p = 0.858). CONCLUSION: The incidence of breast cancer-related death is probably sufficiently low to avoid postoperative RT in women aged ≥65 years with TC of the breast after BCS.

Lymph node ratio has prognostic value related to the number of positive lymph nodes in patients with vulvar cancer.

AIM: We investigated the value of the number of positive lymph nodes (PLNs) and lymph node ratio (LNR) on survival of vulvar cancer patients. METHODS: A total of 2332 patients with vulvar squamous cell carcinoma were included from the SEER program. RESULTS: In multivariate analysis, the number of PLNs and LNR were independent prognostic indictors of survival outcomes, a higher number of PLNs and a higher LNR had poorer survival outcomes. An LNR >0.2 was associated with poor survival outcomes according to the number of PLNs. CONCLUSION: The LNR has prognostic value related to the number of PLNs and may allow a more accurate determination of the lymph node status of vulvar cancer patients.

Widowed status increases the risk of death in vulvar cancer.

AIM: To evaluate the effect of marital status on survival of patients with vulvar cancer. MATERIALS & METHODS: A total of 4001 patients with vulvar cancer were included from the SEER database. Statistical analyses were performed using χ2 test, Kaplan-Meier method, Cox regression proportional hazards and a 1:1 propensity score-matching. RESULTS: The 8-year vulvar cancer-related survival in married, divorced, single and widowed patients were 78.6, 82.2, 78.9 and 61.6%, respectively (p < 0.001). In multivariate analysis, widows patients had significantly worse vulvar cancer survival than the nonwidowed counterparts in unmatched and matched populations. CONCLUSION: Being widowed is associated with greater risk of vulvar cancer mortality than the nonwidowed counterparts.

The Clinicopathological Features and Survival Outcomes of Different Histological Subtypes in Triple-negative Breast Cancer.

Purpose: To determine the clinicopathological features and survival outcomes of triple-negative breast cancer (TNBC) according to different histological subtypes. Methods: Using the Surveillance, Epidemiology, and End Results database, we included TNBC cases in 2010-2013. The effect of histological subtype on breast cancer-specific survival (BCSS) and overall survival (OS) were analyzed using univariate and multivariate analyses. Results: A total of 19,900 patients were identified. Infiltrating ductal carcinoma not otherwise specified accounted for 91.6% of patients, followed by metaplastic carcinoma (2.7%), medullary carcinoma (1.4%), mixed lobular-ductal carcinoma (1.4%), lobular carcinoma (1.3%), apocrine carcinoma (1.0%), and adenoid cystic carcinoma (0.6%). Medullary carcinoma was more frequently poorly/undifferentiated. Significantly more lobular carcinoma, mixed lobular-ductal carcinoma, and metaplastic carcinoma patients had larger tumors. Adenoid cystic carcinoma, metaplastic carcinoma, medullary carcinoma, and apocrine carcinoma were more frequently node-negative. Lobular carcinoma (16.0%) and mixed lobular-ductal carcinoma (10.4%) more frequently had distant stage at initial diagnosis. Histologic subtype was an independent prognostic factor of BCSS and OS. Compared with infiltrating ductal carcinoma, medullary carcinoma and apocrine carcinoma had better BCSS and OS, while mixed lobular-ductal carcinoma and metaplastic carcinoma had worse survival. Adenoid cystic carcinoma survival was not significantly different from that of infiltrating ductal carcinoma. Conclusions: TNBC histological subtypes have different clinicopathological characteristics and survival outcomes. Medullary carcinoma and apocrine adenocarcinoma have excellent prognosis; mixed lobular-ductal carcinoma and metaplastic carcinoma are the most aggressive subtypes.

Survival in signet ring cell carcinoma varies based on primary tumor location: a Surveillance, Epidemiology, and End Results database analysis.

BACKGROUND: The aim of this study was to investigate the survival of patients with signet ring cell carcinoma (SRCC) based on primary tumor location. METHODS: Patient data were obtained from the Surveillance, Epidemiology, and End Results database (1988-2012) with ≥200 cases per tumor location. Cox regression analysis was used to investigate prognostic factors of cause-specific survival (CSS). RESULTS: We identified 24,171 patients. Of the patients, 63.4% had gastric SRCC, followed by colon (18.2%), esophageal (5.0%), rectal (3.5%), lung (3.1%), pancreatic (1.8%), breast (1.5%), bladder (1.3%), small intestine (1.1%), and gallbladder SRCC (1.0%). The 5-year CSS was 22.1%, 69.0%, 33.2%, 28.1%, 24.8%, 16.1%, 13.6%, 12.6%, 11.0%, 6.4% in patients with gastric, breast, colon, rectum, bladder, small intestine, esophageal, gallbladder, lung, and pancreatic SRCC, respectively (P < 0.001). Multivariate analyses showed that the primary tumor location was an independent prognostic factor of survival. Patients with lung, small intestine, and bladder SRCC had a comparable CSS to gastric SRCC, while breast and colorectal SRCC had better survival than gastric SRCC. Esophageal, gallbladder, and pancreatic SRCC were significantly associated with poor CSS compared with gastric SRCC. CONCLUSION: Our study suggests a major difference in survival of SRCC based on the primary tumor locations.

Comparable Survival between Additional Radiotherapy and Local Surgery in Occult Breast Cancer after Axillary Lymph Node Dissection: A Population-based Analysis.

Purpose: To investigate the clinical value of additional local treatment strategies in occult breast cancer (OBC) after axillary lymph node dissection (ALND). Methods: Patients diagnosed with OBC between 1990 and 2013 were included from the Surveillance, Epidemiology, and End Results registry database. The significant risk factors of cause-specific survival (CSS) and overall survival (OS) were identified using univariate and multivariate Cox regression analyses. Results: We identified 980 patients, including 219 (22.3%), 252 (25.7%), 263 (26.8%), and 246 (25.1%) of patients underwent ALND, ALND + radiotherapy (RT), ALND + surgery (S) (mastectomy or breast-conserving surgery), and ALND + S + RT, respectively. Patients with younger age, diagnosed before 2000, advanced nodal stage, ER-negative disease, and PR-negative disease were more likely to undergo additional local treatment compared with ALND only. The 10-year rate CSS of the ALND only group was 57.2%, while that of the ALND + RT, ALND + S, and ALND + S + RT groups was 78.0%, 81.0%, and 71.5%, respectively (p < 0.001). The 10-year OS rate in the ALND only, ALND + RT, ALND + S, and ALND + S + RT groups was 46.0%, 69.5%, 66.1%, and 67.0%, respectively (p < 0.001). Multivariate analysis indicated that older age, advanced nodal stage, and ALND only were independent risk factors for decreased CSS and OS. CSS and OS among the groups including ALND + RT, ALND + S, and ALND + S + RT were not significantly different. Conclusions: Additional local treatment (local surgery or RT) improves survival outcomes compared with ALND only in OBC after ALND. ALND + RT may be the optimal local treatment for OBC due to no different in survival outcomes and cosmesis is better.

The survival benefits of local surgery in stage IV breast cancer are not affected by breast cancer subtypes: a population-based analysis.

This retrospective study aimed to investigate the clinical value of local surgery in stage IV BC and determined whether the survival outcomes were affected by the breast cancer subtype (BCS). Women with de novo stage IV BC from 2010 to 2013 were included using the Surveillance Epidemiology and End Results database. Univariate and multivariate Cox regression analyses were performed to evaluate the prognostic factors for breast cancer-specific survival (BCSS) and overall survival (OS). Among 9,256 patients were identified, 3,130 (33.8%) were received local surgery. Patients with hormone receptor (HR)+/human epidermal growth factor receptor 2 (HER2)- subtype were less likely to receive local surgery, while HR-/HER2- tumors were more likely to receive surgery. Multivariate analyses revealed that local surgery improved survival, surgical intervention was an independent favorable prognostic factor for BCSS (P < 0.001) and OS (P < 0.001). Patients who receipt of surgery had better survival outcomes compared with the non-surgery group, and the survival benefits of local surgery were not affected by the BCS status. Local surgery was improved survival for patients with stage IV BC regardless of the BCS status.

Postoperative radiotherapy for invasive micropapillary carcinoma of the breast: an analysis of Surveillance, Epidemiology, and End Results database.

INTRODUCTION: Invasive micropapillary carcinoma (IMPC) of the breast poses a high risk of locoregional recurrence, and postoperative radiotherapy (PORT) may be beneficial in IMPC. Hence, we determined the clinical value of PORT in IMPC patients. PATIENTS AND METHODS: We assessed clinicopathological factors extracted from the Surveillance, Epidemiology, and End Results database (2004-2013). Univariate and multivariate Cox proportional hazards regressions were performed to assess the independent prognostic factors on breast cancer-specific survival (BCSS) and overall survival (OS). RESULTS: Of the 881 study patients, 444 (50.4%) and 437 (49.6%) underwent breast-conserving surgery (BCS) and mastectomy (MAST), respectively, of whom 357 (80.4%) and 153 (35.0%) underwent PORT, respectively. Patients with young age, large tumor size, or advanced nodal stage were more likely to undergo MAST and PORT compared with MAST alone. Patients with progesterone receptor-positive disease were more likely to receive BCS and PORT compared with BCS alone. The 5-year BCSS and OS were 95.7% and 90.9%, respectively. On multivariate analyses, tumor size, histological grade, and estrogen receptor status were independent predictors of BCSS and OS. The types of surgical procedures (MAST vs. BCS) were not an independent predictor of survival outcomes. Patients who underwent MAST with or without PORT had similar BCSS and OS in the multivariate analyses. Those who underwent BCS plus PORT did not have better BCSS and OS than those who underwent BCS alone. In the low-, intermediate-, and high-risk groups, PORT was not associated with better BCSS and OS than non-PORT groups in patients who received BCS or MAST. CONCLUSION: IMPC has favorable BCSS and OS. Regardless of the types of surgical procedures (MAST or BCS), PORT groups were not inferior to non-PORT groups on BCSS and OS.