PURPOSE: Obesity in women has been shown to have correlation with breast cancer incidence. The proportion of Korean women who are obese has increased recently. However, there is no large-scale study evaluating the relationship between obesity and breast cancer incidence in Korea. In this study, we tried to identify the relationship between obesity and breast cancer incidence in Korean women by using body mass index (BMI). METHODS: A retrospective analysis was performed using single-center data of 28,631 patients screened with breast ultrasonography or mammography between January 2009 to December 2013 in Seoul National University Hospital Healthcare System Gangnam Center. Their clinical characteristics were evaluated. The correlations between breast cancer incidence with BMI and other factors were analyzed using univariate and multivariate logistic regression models. RESULTS: A total of 28,631 patients were enrolled; 67 patients were diagnosed with breast cancer. Among patients without breast cancer, the proportion of patients with BMI under 23 was 68.1%, whereas it was 56.7% among patients with breast cancer (p=0.036). In univariate analysis, patients with a BMI over 25 had an odds ratio of 2.09 for breast cancer compared with those with a BMI under 23 (p=0.012). In addition, patients with a waist circumference over 85 cm had an odds ratio of 1.69 for breast cancer compared with the others (p=0.042). In multivariate analysis, BMI also had significant correlation with breast cancer incidence (odds ratio=1.87, p=0.035). CONCLUSION: An increase in BMI has positive correlation with breast cancer incidence in Korean women. However, a multi-centered prospective study is needed for further evaluation.

Purpose: Sentinel lymph node biopsy (SLNB) alone following neoadjuvant chemotherapy (NAC) remains controversial in patients with breast cancer who are initially lymph nodepositive. The present study aimed to evaluate the impact of SLNB and axillary lymph node dissection (ALND) on breast cancer recurrence and survival in patients who converted from lymph node-positive to pathological node-negative (ypN0) after NAC. Methods: This single-center retrospective study included 223 patients who converted to axillary lymph node-negative status after NAC and underwent breast and axillary surgery between January 2006 and December 2015. This study compared the overall survival (OS), disease-free survival (DFS), ipsilateral axillary lymph node recurrence rates and incidence of postoperative complications, especially, arm lymphedema and shoulder stiffness between SLNB and ALND. Results: This study included 223 patients with axillary pathological complete response (pCR) after NAC and surgery. The SLNB and ALND groups included 94 and 129 patients, respectively. The median follow-up time was 57 (range, 6–155) in the SLNB group and 99 (range 2–159) months in the ALND group. The corresponding 5-year OS and DFS rates were 96.3% and 94.2% (p = 0.392), and 89.2% and 86.4% (p = 0.671), respectively. Four patients (4.3%) in the SLNB group and nine (7.0%) in the ALND group developed locoregional recurrences. Ipsilateral axillary lymph node recurrence and distant metastasis were observed in one (1.1%) and three (2.3%) patients, and in 10 (10.6%) and 11 (8.5%) patients, respectively. Patients in the ALND group were more likely than their SLNB counterparts to experience complications, such as shoulder stiffness (9 [7.0%] vs. 4 [4.3%] patients, p = 0.57). The rate of lymphedema in the ALND group was three times that in the SLNB group (35 [27.1%] vs. 8 [8.5%] patients, p < 0.001). Conclusion As an alternative to ALND, SLNB has oncological safety in patients with axillary pathological complete response after NAC.

Purpose: The Breast Imaging Reporting and Data System (BI-RADS) is a systematic and standardized scheme of the radiological findings of breast. However, there were different BI-RADS categories between breast cancers as the clinical characteristics in previous studies. We analyzed the association of BI-RADS categories with the clinicopathological characteristics and prognosis of breast cancer. Methods: A total of 44,184 patients with invasive breast cancers assigned to BI-RADS category 3, 4, or 5 in preoperative mammography or ultrasonography were analyzed retrospectively using large-scale data from the Korean Breast Cancer Society registration system. The difference in the clinicopathological factors and prognoses according to the BI-RADS categories (BI-RADS 3–4 and BI-RADS 5) were compared between the mammography and ultrasonography groups. Comparisons of the clinicopathological factors in both groups were made using logistic regression analysis, while the prognoses were based on the breast cancer-specific survival using the Kaplan-Meier method and Cox proportional hazards model. Results: The factors associated with BI-RADS were T stage, N stage, palpability, histology grade, and lymphovascular invasion in the mammography group; and N stage, palpability, histology grade, and lymphovascular invasion in the ultrasonography group. In the survival analysis, there were significant differences in the breast cancer-specific survival of the BI-RADS category groups in both of the mammography (hazard ratio [HR], 3.366; P < 0.001) and ultrasonography (HR, 2.877; P < 0.001) groups. Conclusion In this study, the BI-RADS categories of preoperative mammography and ultrasonography of patients with invasive breast cancer were associated with prognosis and could be an important factor in making treatment decisions.

Purpose: The Breast Imaging Reporting and Data System (BI-RADS) is a systematic and standardized scheme of the radiological findings of breast. However, there were different BI-RADS categories between breast cancers as the clinical characteristics in previous studies. We analyzed the association of BI-RADS categories with the clinicopathological characteristics and prognosis of breast cancer. Methods: A total of 44,184 patients with invasive breast cancers assigned to BI-RADS category 3, 4, or 5 in preoperative mammography or ultrasonography were analyzed retrospectively using large-scale data from the Korean Breast Cancer Society registration system. The difference in the clinicopathological factors and prognoses according to the BI-RADS categories (BI-RADS 3–4 and BI-RADS 5) were compared between the mammography and ultrasonography groups. Comparisons of the clinicopathological factors in both groups were made using logistic regression analysis, while the prognoses were based on the breast cancer-specific survival using the Kaplan-Meier method and Cox proportional hazards model. Results: The factors associated with BI-RADS were T stage, N stage, palpability, histology grade, and lymphovascular invasion in the mammography group; and N stage, palpability, histology grade, and lymphovascular invasion in the ultrasonography group. In the survival analysis, there were significant differences in the breast cancer-specific survival of the BI-RADS category groups in both of the mammography (hazard ratio [HR], 3.366; P < 0.001) and ultrasonography (HR, 2.877; P < 0.001) groups. Conclusion In this study, the BI-RADS categories of preoperative mammography and ultrasonography of patients with invasive breast cancer were associated with prognosis and could be an important factor in making treatment decisions.

This article provides an annual update of Korean breast cancer statistics, including the incidence, tumor stage, type of surgical treatment, and mortality. The data was collected from the Korean Breast Cancer Society registry system and Korean Central Cancer Registry.In 2019, 29,729 women were newly diagnosed with breast cancer. Breast cancer has continued to increase in incidence since 2002 and been the most common cancer in Korean women since 2019. Of the newly diagnosed cases in 2019, 24,820 (83.5%) were of invasive carcinomas, and 4,909 (16.5%) were of carcinoma in situ. The median age of women with breast cancer was 52.8 years, and breast cancer was most commonly diagnosed in the age group of 40–49 years. The number of patients who have undergone breast conserving surgery has continued to increase since 2016, with 68.6% of patients undergoing breast conserving surgery in 2019. The incidence of early-stage breast cancer continues to increase, with stage 0 or I breast cancer accounting for 61.6% of cases. The most common subtype of breast cancer is the hormone receptor-positive human epidermal growth factor receptor 2-negative subtype (63.1%). The 5-year relative survival rate of patients with breast cancer from 2015 to 2019 was 93.6%, with an increase of 14.3% compared to that from 1993 to 1995. This report improves our understanding of breast cancer characteristics in South Korea.

Breast cancer is the most common malignancy in Korean women, and its incidence continues to increase. The Korean Breast Cancer Society (KBCS) established a nationwide breast cancer database through its online enrollment program in 1996. This study aimed to analyze the clinical characteristics of breast cancer in Korea, and to assess the pattern of changes in breast cancer management in 2018. We analyzed the KBCS and Korea Central Cancer Registry (KCCR) databases in 2018. In 2018, 28,157 patients were newly diagnosed with breast cancer, of whom 4,510 had noninvasive breast cancer and 23,647 had invasive breast cancer. The age-standardized rate of breast cancer in 2018 was 79.0 per 100,000 women (65.6 invasive, 13.4 noninvasive). The median age of female patients diagnosed with breast cancer in 2018 was 52 years, and the incidence of breast cancer was the highest in the 40–49-years age group (9,432 patients, 33.6%). The proportion of patients with stage 0 and stage I breast cancer continued to increase, accounting for 63.8% of cases, and breast-conserving surgery was performed more often than mastectomy (66.2% vs. 33.0%). The most common subtypes of breast cancer were hormone receptor [HR]-positive and human epidermal growth factor receptor-2 (HER2)-negative types (65.9% of cases), while the HR-negative and HER2-positive types accounted for 9.2% of cases. According to the KCCR data, from 2014 to 2018, the 5-year relative survival rate of patients with breast cancer was 93.3%, which was 14.0% higher than that from 1993 to 1995 (79.3%). The clinical characteristics of breast cancer in Korea have been changing, and national databases can improve our understanding of the disease characteristics of Korean women. Therefore, updating the KBCS registry is important for the effective management of breast cancer in Korea.

Breast cancer is the most common malignancy in Korean women, and its incidence continues to increase. The Korean Breast Cancer Society (KBCS) established a nationwide breast cancer database through its online enrollment program in 1996. This study aimed to analyze the clinical characteristics of breast cancer in Korea, and to assess the pattern of changes in breast cancer management in 2018. We analyzed the KBCS and Korea Central Cancer Registry (KCCR) databases in 2018. In 2018, 28,157 patients were newly diagnosed with breast cancer, of whom 4,510 had noninvasive breast cancer and 23,647 had invasive breast cancer. The age-standardized rate of breast cancer in 2018 was 79.0 per 100,000 women (65.6 invasive, 13.4 noninvasive). The median age of female patients diagnosed with breast cancer in 2018 was 52 years, and the incidence of breast cancer was the highest in the 40–49-years age group (9,432 patients, 33.6%). The proportion of patients with stage 0 and stage I breast cancer continued to increase, accounting for 63.8% of cases, and breast-conserving surgery was performed more often than mastectomy (66.2% vs. 33.0%). The most common subtypes of breast cancer were hormone receptor [HR]-positive and human epidermal growth factor receptor-2 (HER2)-negative types (65.9% of cases), while the HR-negative and HER2-positive types accounted for 9.2% of cases. According to the KCCR data, from 2014 to 2018, the 5-year relative survival rate of patients with breast cancer was 93.3%, which was 14.0% higher than that from 1993 to 1995 (79.3%). The clinical characteristics of breast cancer in Korea have been changing, and national databases can improve our understanding of the disease characteristics of Korean women. Therefore, updating the KBCS registry is important for the effective management of breast cancer in Korea.

This article describes the breast cancer statistics in Korea, including the incidence, type of surgical procedure, stage, and molecular subtype, using the Korean Breast Cancer Society (KBCS) and Korea Central Cancer Registry data. There were a total of 26,534 new breast cancer diagnoses in 2017 in Korea, of which 4,139 were carcinoma in situ cases and 22,395 were invasive cancer cases. The age standardized rate of breast cancer was 75.3 per 100,000 women in 2017 (63.0 of invasive carcinoma and 12.3 of carcinoma in situ), and it has been steadily increasing across all age groups. Breast cancer occurred most commonly in the 40–49 age group. Compared to 2016, breast conserving surgery (BCS) has increased, and 67.4% of patients were treated with BCS in 2017. The proportions of stage 0 and stage I have continued to increase, accounting for 60.7%. The most common subtype of breast cancer was hormone receptor (HR) positive and human epidermal growth factor receptor-2 (HER2) negative type comprising 65.9% of the cases, whereas HR negative and HER2 positive type was the rarest comprising 10.2% of the cases. The 5-year relative survival rate of breast cancer patients had increased by 14.0% from 79.2% in 1993–1995 to 93.2% in 2013–2017. It is essential to actively enter breast cancer data into the KBCS registry to improve our understanding.