Korean Breast Cancer Society Registry Research Articles

Clinical characteristics and prognosis of postpartum breast cancer.

Postpartum breast cancer (PPBC) is a not well-established subset of breast cancer, and only few studies address its poorer prognosis. However, previous studies show that PPBC is associated with worse outcome with higher rates of metastasis than in young women's breast cancer (YWBC). We aimed to analyze the clinical characteristics and prognosis of PPBC based on the diagnosis period of PPBC. We retrospectively reviewed 208,780 patients with breast cancer from the Korean Breast Cancer Society registry (KBCSR) database between January 2000 and December 2014. We included premenopausal women aged 20-50years who underwent breast cancer surgery. The patients were classified by 5-year intervals according to the diagnosis period of breast cancer, from the first birth to the breast cancer diagnosis. Compared with patients in the other groups, patients diagnosed within postpartum 5years (PPBC < 5years) group were younger, had a more advanced stage, had lower estrogen receptor (ER) and progesterone receptor (PR) expression, and had a higher human epidermal growth factor receptor 2 (HER2) positive rate. Further, PPBC < 5years group had a worse survival rate than the nulliparous and other groups (5-year cumulative survival: PPBC < 5years group, 89%; nulliparous group, 97.3%; 5 ≤ PPBC < 10years group, 93%). In the multivariate analysis, the PPBC < 5years group was associated with a worse survival rate (hazard ratio 1.55, 95% confidence interval [CI] 1.148-2.094, p 0.004) after adjustment for age at diagnosis, breast cancer stage, ER and HER2 status, Ki-67 level, and chemotherapy. Our findings indicated that patients diagnosed with breast cancer within the first 5years after delivery had aggressive characteristics and a poor survival rate. It is important to elucidate the pathophysiology of PPBC and establish novel therapeutic strategies to improve the survival rate.

Abstract P6-05-59: Clinical Characteristics and Prognosis of Postpartum Breast Cancer

Abstract Background: Postpartum breast cancer (PPBC) is a not well-established subset of breast cancer, and only few studies address its poorer prognosis. However, there are previous studies that PPBC is associated with worse outcome with higher rates of metastasis than in young women’s breast cancer (YWBC). The purpose of this study was to analyze the clinical characteristics and prognosis according to the onset period of PPBC, Materials and methods: 208,780 breast cancer patients from the online Korean Breast Cancer Society (KBCS) registry database between January 2000 and December 2014 were reviewed retrospectively. Premenopausal women aged 20 to 50 years who underwent breast cancer surgery were included. According to the diagnosis period of breast cancer, it was classified into groups diagnosed within 5 years (PPBC&amp;lt; 5) after delivery, between 5-10 years((5≤PPBC&amp;lt; 10), and after 10 years(PPBC≥10). Results: The patients in PPBC &amp;lt; 5 group showed a younger and more advanced stage compared to other groups, and the expression of estrogen receptor (ER) and progesterone receptor (PR) was lower and the HER2 positive rate was higher. PPBC&amp;lt; 5 group had worse survival rate compared to nulliparous and other group (5-year cumulative survival; PPBC&amp;lt; 5 group, 89% vs. nulliparous group, 97.3% vs. 5≤ PPBC&amp;lt; 10 group 93%). In multivariate analysis, PPBC&amp;lt; 5 group was associated with worse survival rate (Hazard ratio 1.55, 95% CI 1.148-2.094, p=0.004) after adjustment for age at diagnosis, breast cancer stage, ER and HER2 status, Ki-67 level, and chemotherapy. Conclusion: We demonstrated that patients with breast cancer diagnosed within first five years after delivery had aggressive characteristics and a worse survival rate. In order to improve the survival rate of PPBC, the cause should be identified and new therapeutic strategy should be established. Citation Format: Soo Youn Bae, Pill Sun Paik, Young Joo Lee, Young-Joon Kang. Clinical Characteristics and Prognosis of Postpartum Breast Cancer [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P6-05-59.

Breast Cancer Statistics in Korea, 2019.

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.

189P Characteristics and prognosis of breast cancer patients who have experienced hormone replacement therapy: From the Korean Breast Cancer Society Registry database

Hormone replacement therapy (HRT) is a risk factor for breast cancer (BC). The characteristics and prognosis of HRT-related BC are not well known. We have evaluated the characteristics and prognosis of BC in a cohort of Korea patients who have experienced HRT.

Abstract P3-12-14: Attenuated negative prognostic effect of progesterone receptor negativity in postmenopausal ER+ breast cancer with normal BMI (&amp;lt;25): A nation-wide study in Korean Breast Cancer Society and the institutional cohort

Abstract Purpose Loss of progesterone receptor (PR) expression is a poor prognostic factor in ER+/HER2- breast cancer. A growing body of evidence suggests that PR expression is affected by endogenous estrogen level and modulated by body mass index (BMI). Using Korean Breast Cancer Society Registry (KBCSR) and institutional database, we evaluated survival outcome by PR expression in the postmenopausal groups stratified by BMI. Moreover, we investigated 21-gene recurrence score to assess intrinsic tumor biology. Method Data from the KBCSR for patients diagnosed with invasive breast cancer when aged over 50 years were reviewed, and 33,314 with BMI were included. Of these, we investigated overall survival (OS) of women at age of 60 and older with a median follow-up of 56 months (n=9,492). In the institutional cohort with ER+HER2- breast cancer women at age of 50 and older (n=703), the landmark survival analyses were performed to address the 5-years recurrence-free survival (RFS). In the subset of the institutional cohort, 21-gene recurrence scores were identified in individuals (n=470). Normal weight is defined as BMI less than 25kg/m2. Result Among the postmenopausal women from the KBCSR, the PR- was significantly associated with adverse OS (hazard ratio [HR], 1.39; 95% CI, 1.16-1.67; p&amp;lt;0.001) in high BMI group (≥25) whereas in normal BMI group (&amp;lt;25) did not (HR, 1.07; 95% CI, 0.89-1.29; p=0.498) (interaction p=0.046). In the institutional cohort with ER+/HER2- postmenopausal women (age&amp;gt;50), RFS was superior in the PR+ than in the PR- in the postmenopausal with high BMI (≥25). In contrast, RFS was not separated by PR in the normal BMI group (&amp;lt;25). When we compared the 21-gene recurrence score according to PR, the scores were significantly lower in the PR+ than in the PR- regardless of BMI. Conclusion In ER+/HER2- aged postmenopausal breast cancer women with normal BMI who have low estrogen environment, negative prognostic effect of absence of PR expression is attenuated. Bad tumor biology of PR- cancer is conserved irrespective of BMI. We support the hypothesis that weight control to reduce endogenous estrogen produced by adipose tissue is beneficial for postmenopausal women with ER+ breast cancer. Citation Format: Soong June Bae, Jawon Hwang, Janghee Lee, Jung Hwan Ji, Chihhao Chu, Jee Hung Kim, Sung Gwe Ahn, Joon Jeong. Attenuated negative prognostic effect of progesterone receptor negativity in postmenopausal ER+ breast cancer with normal BMI (&amp;lt;25): A nation-wide study in Korean Breast Cancer Society and the institutional cohort [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P3-12-14.

Omission of chemotherapy for hormone receptor-positive and human epidermal growth factor receptor 2-negative breast cancer: patterns of treatment and outcomes from the Korean Breast Cancer Society Registry.

Although adjuvant chemotherapy (CTx) is still recommended for high-risk patients with hormone receptor-positive and human epidermal receptor (HER)-2-negative breast cancer, recent studies found that selected patients with low disease burden may be spared from CTx and receive hormonal treatment (HT) alone. This study aims to evaluate the trends of treatment (CTx + HT vs. HT alone) in Korea and to assess the impact on overall survival (OS) according to treatment pattern. The Korean Breast Cancer Society Registry was queried (2000 to 2018) for women with pT1-2N0-1 hormone receptor-positive and HER2-negative disease who underwent surgery and adjuvant systemic treatment (CTx and HT). Clinicopathologic factors, change in pattern of treatment over time, and OS for each treatment option were analyzed. A total of 40,938 women were included in the study; 20,880 (51.0%) received CTx + HT, while 20,058 (49.0%) received HT only. In recent years, there has been a steady increase in the use of HT alone, from 21.0% (2000) to 64.6% (2018). In Cox regression analysis, age, type of breast and axillary operations, T and N stages, body mass index, histologic grade, and presence of lymphovascular invasion were prognostic indicators for OS. There was no significant difference between CTx + HT and HT alone in terms of OS (P = 0.126). Over the years, there has been a shift from CTx + HT to HT alone without a significant difference in OS. Therefore, HT alone could be a safe treatment option in selected patients, even those with T2N1 disease.

Relationship Between Breast and Axillary Pathologic Complete Response According to Clinical Nodal Stage: A Nationwide Study From Korean Breast Cancer Society.

PurposeWe evaluated the relationship between breast pathologic complete response (BpCR) and axillary pathologic complete response (ApCR) after neoadjuvant chemotherapy (NACT) according to nodal burden at presentation. As the indications for NACT have expanded, clinicians have started clinical trials for the omission of surgery from the treatment plan in patients with excellent responses to NACT. However, the appropriate indications for axillary surgery omission after excellent NACT response remain unclear.MethodsData were collected from patients in the Korean Breast Cancer Society Registry who underwent NACT followed by surgery between 2010 and 2020. We analyzed pathologic axillary nodal positivity after NACT according to BpCR stratified by tumor subtype in patients with cT1-3/N0-2 disease at diagnosis.ResultsA total of 6,597 patients were identified. Regarding cT stage, 528 (9.5%), 3,778 (67.8%), and 1,268 (22.7%) patients had cT1, cT2, and cT3 disease, respectively. Regarding cN stage, 1,539 (27.7%), 2,976 (53.6%), and 1,036 (18.7%) patients had cN0, cN1, and cN2 disease, respectively. BpCR occurred in 21.6% (n = 1,427) of patients, while ApCR and pathologic complete response (ypCR) occurred in 59.7% (n = 3,929) and ypCR 19.4% (n = 1,285) of patients, respectively. The distribution of biologic subtypes included 2,329 (39.3%) patients with hormone receptor (HR)-positive/human epidermal growth factor receptor 2 (HER2)-negative disease, 1,122 (18.9%) with HR-positive/HER2-positive disease, 405 (6.8%) with HR-negative/HER2-positive disease, and 2,072 (35.0%) with triple-negative breast cancer . Among the patients with BpCR, 89.6% (1,122/1,252) had ApCR. Of those with cN0 disease, most (99.0%, 301/304) showed ApCR. Among patients with cN1-2 disease, 86.6% (821/948) had ApCR.ConclusionBpCR was highly correlated with ApCR after NACT. In patients with cN0 and BpCR, the risk of missing axillary nodal metastasis was low after NACT. Further research on axillary surgery omission in patients with cN0 disease is needed.

Low incidence of lymph node metastasis in patients with microinvasive breast cancer: a Korean nationwide study.

PurposeMicroinvasive breast cancer (MIBC) is an invasive carcinoma with a tumor dimension not exceeding 1 mm. Owing to its low incidence, the rate of axillary node metastasis and its management are not well established. The aim of this study was to assess the incidence of lymph node metastasis (LNM) and identify variables associated with LNM, as well as to evaluate the need for axillary staging in MIBC patients by analyzing nationwide data.MethodsThe Korean Breast Cancer Society registry was searched to identify MIBC patients diagnosed between January 1996 and April 2020. Patients without neoadjuvant chemotherapy experiences, systemic metastasis, and missing or discordant data were eligible for the analysis. The incidence rate of LNM was determined, and variables associated with LNM were identified by multivariable regression analysis.ResultsOf 2,427 MIBC patients identified, 98 (4.0%) had LNM and 12 (0.5%) had N2/3 disease. Type of breast operation (odds ratio [OR], 2.093; 95% confidence interval [CI], 1.332–3.290; P = 0.001), age (OR, 2.091; 95% CI, 1.326–3.298; P = 0.002), hormone receptor status (OR, 2.220; 95% CI, 1.372–3.594; P = 0.001), and lymphovascular invasion (OR, 11.143; 95% CI, 6.354–19.540; P < 0.001) were significantly related to LNM.ConclusionThe incidence of LNM in MIBC patients was only 4.0% in our study, suggesting that de-escalation of axillary surgical interventions could be carefully considered. The indications for axillary staging should be individualized considering tumor volume, age, hormone receptor status, and lymphovascular invasion to improve the quality of life of MIBC survivors.

Abstract PS1-54: Risk factors for lymph node metastasis and the role of SLNB in microinvasive breast cancer

Abstract Introduction Incidence of microinvasive Breast cancer (DCISM) along with ductal carcinoma in situ is increasing due to mammographic screening. However, DCISM is not a common pathologic entity and surgical management of the axilla, overall treatment, and prognosis of this entity still remains unclear. Our study aims to determine whether sentinel lymph node biopsy (SLNB) is necessary for all DCISM patients and analyze the characteristics of lymph node-positive patients among DCISM patients to identify risk factors associated with lymph node metastasis. Materials and MethodsA total of 184,007 Breast cancer patients treated were registered in the Korean Breast Cancer Society Registry between 1978 to 2020. A retrospective review of the database was performed and the analysis includes diagnostic and clinic-pathologic characteristics such as positive lymph node and immunohistochemistry. A univariate analysis was carried out to determine associations between lymph node positivity and the clinical variables via Fisher’s exact test.ResultsOf the 184,007 patients, 2,556 (1.4%) breast cancer patients were classified as DCISM and 134 (5.2%) had at least one lymph node (node-positive), while 2,422 were node-negative patients. We found statistically significant results with hormone receptor status between node-positive and node-negative patients. Estrogen receptor (ER) and progesterone receptor (PR)-negative cases were associated with lower ORs (ER: OR=0.63, 95CI=0.43-0.92, P=0.016; PR: 0.67, 0.46-0.96, 0.026, respectively). A particularly interesting finding is that human epidermal growth factor receptor 2 (HER2)-negative cases were associated with higher OR (HER2: 2.03, 1.36-3.06, 0.001), suggesting hormone receptor status could be useful to identify potential lymph node metastases.ConclusionOur study suggests that we could omit axillary staging in DCISM patients, and consider optional SLNB in patients with ER, PR, and HER2 status with other overrepresented clinical entities such as palpable mass, BMI, and histologic grade.KeywordsMicroinvasive ductal carcinoma, Sentinel lymph node biopsy, lymph node metastasis Citation Format: Pill Sun Paik, Min Kyung Cho, Juneyoung Ahn, Chang Ik Yoon, Tae-Kyung Yoo, Woo-Chan Park. Risk factors for lymph node metastasis and the role of SLNB in microinvasive breast cancer [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS1-54.

Clinical significance of HER2 status in T1bN0 breast cancer: a nationwide study from the Korean Breast Cancer Society.

The prognosis of patients with node-negative T1b tumors according to human epidermal growth factor receptor 2 (HER2) status is not known. This group of patients has not been studied in the available randomized trials. The objective of this study was to evaluate the survival of patients in a monoethnic group diagnosed with T1b lymph node-negative breast cancer depending on HER2 status. We analyzed 3110 patients with T1bN0M0 breast cancer whose data were deposited into the Korean Breast Cancer Society Registry database between 2000 and 2009. Overall survival (OS) and breast cancer-specific survival (BCSS) were compared according to HER2 status. Among all patients, 494 (15.9%) had HER2-positive breast cancer. At a mean follow-up of 93months, 108 deaths and 86 breast cancer-specific deaths were noted among all patients. There was no significant difference in OS between the HER2-negative and HER2-positive groups (p = 0.103). The same result was observed for BCSS. However, in the subgroup of estrogen receptor (ER)-positive women, HER2-negative patients had a better BCSS prognosis than HER2-positive patients (p = 0.025). Multivariate analysis also indicated a significant difference in BCSS in the ER-positive subgroup (HR 2.60; 95% CI 1.15-5.87; p = 0.021). This study analyzed a large nationwide and monoethnic cohort and found a significant difference only in BCSS in the ER-positive subgroup according to HER2 status. Anti-HER2 therapy may be considered in HER2-positive and ER-positive patients with small, node-negative breast cancer.

Characteristics and prognosis of 17 special histologic subtypes of invasive breast cancers according to World Health Organization classification: comparative analysis to invasive carcinoma of no special type.

Breast cancer is a heterogeneous disease with various histopathologic subtypes. Except for invasive carcinoma of no special type (NST), other subtypes are rare with limited data. The purpose of this study was to analyze the characteristics and prognosis of special histopathologic subtypes of breast cancer compared to NST. A total of 136,140 patients were analyzed using the Korean Breast Cancer Society Registry database between January 1996 and March 2019. The clinicopathologic features and survival outcomes of special type breast carcinoma were compared with those of NST. The prevalence of special subtypes other than NST was 13.7% (n = 18,633). Compared to NST, patients with lobular, medullary, metaplastic, and micropapillary carcinoma had larger tumors (p < 0.001). Patients with mucinous, tubular, medullary, metaplastic, and cribriform carcinoma presented with less node metastasis (p < 0.001), contrary to patients with micropapillary carcinoma. Patients with lobular, mucinous, tubular, papillary, and cribriform carcinoma presented as luminal A subtype much more often (p < 0.001). Micropapillary carcinoma included more luminal B subtype (p < 0.001). Typically, medullary and metaplastic carcinoma included more triple-negative subtypes (p < 0.001). In survival analysis, only medullary (Hazard Ratio (HzR) 0.542, 95% CI 0.345 to 0.852, p = 0.008) and metaplastic carcinoma (HzR 1.655, 95% CI 1.317 to 2.080, p < 0.001) showed significantly different overall survival from NST by multivariate analysis. Breast cancer had distinct clinicopathologic features according to histopathologic subtype. However, special types of breast cancer had similar survival outcomes compared to NST when adjusting for other prognostic factors, except for metaplastic carcinoma and medullary carcinoma.

Breast Cancer Statistics in Korea in 2017: Data from a Breast Cancer Registry.

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.

11P - The prognosis of rare histopathologic subtype of breast cancer

BackgroundBreast cancer is a heterogeneous disease with various histopathologic subtypes. As the prevalence of special types of breast cancer other than invasive carcinoma of no special type (NST) is low, limited data about the clinical behavior and prognosis according to the histologic types were documented with discordant results. The purpose of this study was to analyze the characteristics and the prognosis of rare histopathologic subtype of breast cancer compared with NST and to understand better for proper management. MethodsA total of 133,969 patients were analyzed in this study among the patients who were registered in the Korean Breast Cancer Society Registry database between January 1996 and March 2019 in Korea. ResultsThe prevalence of special types of breast cancer other than NST was 13.7% (n = 18,633). The patients with lobular, mucinous, tubular, papillary, and cribriform carcinoma presented as luminal A subtype much more than NST (77.6%, 74.6%, 77.2%, 57.4%, and 78.1% vs 47.5%, respectively, p < 0.001). A micropapillary carcinoma included more luminal B subtype with even high K-67 expression or positive HER2 than NST (40.9% vs 29.5%, p < 0.001). Typically, medullary and metaplastic carcinoma included more triple negative breast cancer (44.8% and 64.8% vs 13.5%, p < 0.001) than NST. In survival analysis, lobular (HR 0.879, p = 0.029), mucinous (HR 0.529, p < 0.001), tubular (HR 0.781, p < 0.001), papillary (HR 0.728, p < 0.001), medullary (HR 0.500, p < 0.001), and cribriform carcinoma (HR 0.291, p = 0.001) showed better overall survival than NST, and metaplastic carcinoma (HR 1.995, p < 0.001) showed worse outcome significantly. However, after adjusting for age, stage, molecular subtypes, grade, and lymphovascular invasion, only metaplastic carcinoma showed different overall (HR 1.762, p < 0.001) and breast cancer-specific survival (HR 1.685, p = 0.012) from NST. ConclusionsIn conclusion, invasive breast cancer had specific clinical and pathologic features according to the histopathologic subtype. However, special types of breast cancer other than NST have similar survival outcomes compared to NST when adjusting for other prognostic factors, except for metaplastic carcinoma. Editorial acknowledgementThis research was supported by the Korean Breast Cancer Society. Legal entity responsible for the studyThe authors. FundingHas not received any funding. DisclosureAll authors have declared no conflicts of interest.

276P - The prognostic significance of preoperative tumour marker (CEA, CA15-3) elevation in breast cancer patients

BackgroundTumour markers are widely used for screening and monitoring cancers. CA 15-3 and CEA are FDA-approved tumour markers for monitoring breast cancer. However, the prognostic efficacy of preoperative elevation of CEA and CA15-3 levels in breast cancer remains controversial. MethodsWe retrospectively analyzed the clinicopathological parameters and preoperative serum CEA and CA 15-3 level of 149,238 patients of Korean Breast Cancer Society Registry (KBCSR) Database who underwent surgery between January 2000 and December 2015. ResultsThe patients with elevated CA 15-3/CEA level had shown more advanced T stage and N stage, ER negativity, PR negativity and HER2 positivity compared the patients with normal CA15-3/CEA levels. The patients with elevated CA 15-3/CEA level had worse OS than the patients with normal CA 15-3/CEA level. In survival analysis, both elevated group had worst prognosis compared other groups. In subgroup analysis by subtypes, in luminal A, both elevated group had hazard ratio (HR) 2.14 (95% CI 1.01-4.55), only CA 15-3 elevated had HR 2.38 (95% CI 1.58-3.58) and only CEA elevated group had HR 1.79 (95% CI, 1.20-2.68), compared normal group. In luminal B, both elevated group had HR 3.99 (95% CI 2.23-7.16), only CA 15-3 elevated had HR 2.38 (95% CI 1.58-3.58) and only CEA elevated group had HR 1.79 (95% CI, 1.20-2.68), compared normal group. In HER2 subtype group, elevated CEA level was the only independent prognostic factor. However, in TNBC, elevated preoperative CEA and CA 15-3 level were not a significant prognostic factor for OS. ConclusionsThe elevation of preoperative tumor markers was associated with aggressive characteristic and worse overall survival. Preoperative tumor markers predicted the prognosis of the patients and showed differences according to subtypes. In luminal breast cancer, the CA 15-3 elevation has higher hazard ratio than the CEA elevation and the patients with both tumor markers showed the worst prognosis. Legal entity responsible for the studyThe authors. FundingHas not received any funding. DisclosureAll authors have declared no conflicts of interest.

220P - Prognosis of mastectomy with reconstruction after neoadjuvant chemotherapy: A nationwide study of the Korean Breast Cancer Society

BackgroundWe compared the prognosis of patients with breast cancer according to surgical options including mastectomy with reconstruction after neoadjuvant chemotherapy (NAC). We also assessed the association between prognosis and surgical options according to clinical stage and clinical response in patients with neoadjuvant chemotherapy. MethodsA total of 140,712 patients were enrolled in the Korean Breast Cancer Society Registry database between 2000 and 2014 in Korea. We compared the prognosis of three groups; 1) patients who underwent breast-conserving surgery (BCS), 2) patients who underwent mastectomy, and 3) patients who underwent mastectomy with reconstruction. ResultsOf all 6,634 patients who were treated with NAC, 1,745 patients underwent BCS, 1,459 patients underwent mastectomy, and 363 patients underwent mastectomy with reconstruction. In survival analysis, five-year survival rate (5YSR) of mastectomy with BR group was not inferior compare to other groups in clinical stage IIA and IIB. 5YSR of mastectomy with BR group was 100% and 90.0% clinical stage IIA and IIB, whereas 5YSR of mastectomy group was 97.2% and 86.2% (clinical stage IIA and IIB; P=0.033 and 0.023). In clinical stage IIIA and IIIB, there was no significant difference in 5YSR between mastectomy with BR group and other groups. However, women who underwent mastectomy with BR had a worse prognosis compare to BCS or mastectomy group in clinical stage IIIC. In univariate analysis by Cox regression method according to surgical methods, women who underwent mastectomy with BR had a worse prognosis compared to other groups in patients with clinical stage IIIC (HR 5.88; 95% CI 2.17-15.89; P < 0.001). In multivariate analysis, women who underwent mastectomy with reconstruction followed by NAC were associated with a worse prognosis in clinical stage IIIC. (HR 3.41; 95% CI 1.29-8.99; P=0.013). ConclusionsIn this study, women who underwent mastectomy with reconstruction followed by NAC were associated with a worse prognosis in the clinically advanced stage. This study suggests that reconstruction followed by NAC should be considered for appropriately selected patients. Legal entity responsible for the studyThe authors. FundingHas not received any funding. DisclosureAll authors have declared no conflicts of interest.

The prognostic significance of preoperative tumor marker (CEA, CA15-3) elevation in breast cancer patients: data from the Korean Breast Cancer Society Registry.

Tumor markers such as carcinoembryonic antigen (CEA) and cancer antigen 15-3 (CA15-3) are widely used for monitoring breast cancer. However, the prognostic efficacy of preoperative elevations of CEA and CA15-3 levels in breast cancer patients remains controversial. We retrospectively analyzed the clinicopathological parameters of 149,238 patients in the Korean Breast Cancer Society Registry Database who underwent surgery between January 2000 and December 2015. The patients with elevated CA15-3/CEA levels had worse overall survival (OS) than the patients with normal CA15-3/CEA levels. For the luminal A subtype, the CA15-3- and CEA-elevated group had a hazard ratio (HR) of 2.14 (95% CI 1.01-4.55). The CA15-3-elevated group had an HR of 2.38 (95% CI 1.58-3.58) and the CEA-elevated group had an HR of 1.79 (95% CI 1.20-2.68) compared to the normal group. For the luminal B subtype, the CA15-3- and CEA-elevated group had an HR of 3.99 (95% CI 2.23-7.16), whereas the CA15-3-elevated group had an HR of 2.38 (95% CI 1.58-3.58) and the CEA-elevated group had an HR of 1.79 (95% CI 1.20-2.68). For the HER2 subtype, elevated CEA level was the only independent prognostic factor. However, for the triple-negative breast cancer (TNBC) subtype, elevated preoperative CEA and CA15-3 levels were not significant prognostic factors for OS. Preoperative CEA and CA15-3 levels showed varying prognostic ability according to breast cancer subtype. Preoperative CA15-3 and CEA elevation are significant prognostic factors for luminal breast cancer, but they were not significant factors for TNBC.

Clinical Implications According to Diagnostic Methods of Human Epidermal Growth Factor Receptor 2 Positivity in Breast Cancer: A Retrospective Study

Purpose According to American Society of Clinical Oncology/College of American Pathologists guidelines, breast cancer is human epidermal growth factor receptor 2 (HER2) positive if there is HER2 protein overexpression at a 3+ level on immunohistochemistry (IHC 3+) or gene amplification (more than six copies per nucleus) on fluorescence in situ hybridization (FISH+). However, there have been few reports on whether outcomes differ based on diagnosis by these two techniques. In this study, we compared outcomes based on the two methods in patients with HER2-positive breast cancer. Methods This study was a retrospective analysis of HER2-positive breast cancer in 18,304 patients, including 14,652 IHC 3+ patients and 3,652 FISH+ patients from the Korean Breast Cancer Society Registry. We compared breast cancer-specific survival and overall survival based on IHC 3+ and FISH+ status with or without trastuzumab. Results Breast cancer-specific survival was significantly different between the IHC 3+ and FISH+ groups, with 5-year cumulative survival rates of 95.0% for IHC 3+ and 98.5% for FISH+ patients who did not receive trastuzumab (p=0.001) in Kaplan-Meier methods. However, there were no significant differences in breast cancer-specific survival and overall survival between IHC 3+ and FISH+ groups regardless of trastuzumab treatment in Cox proportional hazards models. Conclusion The survival outcomes were not affected by the different two diagnostic methods of HER2-positive breast cancer. Further research to evaluate differences in prognosis and other characteristics according to the diagnostic methods of HER2 positivity is needed in the future. Keywords: Breast neoplasms; ErbB-2 receptor; Fluorescence in situ hybridization; Immunohistochemistry; Survival

Clinical subtypes and prognosis in breast cancer according to parity: a nationwide study in Korean Breast Cancer Society.

We explored the association between parity and the risk of developing a specific subtype of breast cancer. We also assessed the association between parity and prognosis according to subtypes. A total of 158,189 patients were enrolled in the Korean Breast Cancer Society Registry database between 1996 and 2015 in Korea. The database provided information on sex, age, number of parity, surgical method, stage, histological findings, presence of biologic markers, adjuvant therapy, and date and cause of death. The patients with higher parity showed a higher ratio of triple-negative breast cancer (TNBC) and human epidermal growth factor receptor 2 (HER2) subtypes. In univariate analysis, women with TNBC who had more than three children had a worse prognosis compared to other groups (HR 1.83; 95% CI 1.34-2.49; P < 0.001). This association was also observed in women younger than 50years (HR 1.63; 95% CI 1.07-2.48; P = 0.021). In multivariate analysis stratified by subtypes, women who had more than three children were associated with a worse prognosis in TNBC in the total population (HR 1.53; 95% CI 1.11-2.12; P = 0.011). This association was also observed in patients younger than 50years of age (HR 1.53; 95% CI 1.09-2.61; P = 0.017). Women who had more than three children were more likely to develop hormone receptor-negative (HR-) subtypes. Women who had more than three children were associated with worse prognosis in patients younger than 50years of age and in patients with TNBC.

Differences in prognosis and efficacy of chemotherapy by p53 expression in triple-negative breast cancer.

TP53 mutation is the most common mutation in breast cancer, and it is considered a target marker of triple-negative breast cancer (TNBC). We investigated whether expression of p53 detected by immunochemical staining predicts the chemotherapy response of TNBC. A total of 11,393 TNBC patients who had between stage I and stage III enrolled in the Korean Breast Cancer Society Registry database from January 1, 2000 to December 31, 2015. There were 6,331 'p53-positive (+) TNBC' patients and 5062 'p53-negative (-) TNBC' patients. In univariate analysis, p53(+) TNBC had a worse prognosis than p53(-) TNBC in patients not receiving chemotherapy (P = 0.003). However, there was no difference in prognosis between p53(+) TNBC and p53(-) TNBC for patients receiving chemotherapy. In multivariate analysis adjusted for age and stage, the risk of p53(+) TNBC was 1.84 times higher than that of p53(-) TNBC in the non-chemotherapy group. However, there was no difference between p53(+) TNBC and p53(-) TNBC in patients receiving chemotherapy. In p53(+) TNBC, the risk was 0.6-fold lower when chemotherapy was administered than when chemotherapy was not administered. However, in p53(-) TNBC, there was no risk reduction effect by chemotherapy. The prognosis of p53(+) TNBC has worse than p53(-) TNBC, but the risk for survival was significantly reduced with chemotherapy. It suggests that p53(+) TNBC would be more sensitive to chemotherapy than p53(-) TNBC.

Clinical subtypes and prognosis of pregnancy-associated breast cancer: results from the Korean Breast Cancer Society Registry database.

We analyzed the clinicopathologic characteristics and prognosis of pregnancy-associated breast cancer (PABC) according to clinical subtypes to better understand the characteristics of PABC. A total of 83,792 female patients between the ages of 20 and 49 were enrolled in the Korean Breast Cancer Society Registry database from January 1, 1996 to December 31, 2015. 'PABC' is defined as breast cancer diagnosed during pregnancy or within 1year after delivery. Other patients were defined as 'non-PABC' patients. In non-PABC patients, luminal A subtype was the most common (50.2%). In PABC patients, TNBC was the most common (40.4%) subtype, while luminal A comprised 21.2% and HER2 subtype comprised 17.3%. There was a significant difference in overall survival (OS). In non-PABC patients, TNBC had the highest HR (HR 2.3, 95% CI 2.1-2.6). In PABC patients, the luminal B subtype (HR+ HER2-high Ki67) had the highest HR at 7.0 (95% CI 1.7-29.1). In multivariate analysis of OS by subtypes, PABC patients had significantly higher HR than non-PABC patients in the HER2 subtype (HR 2.0, 95% CI 1.1-3.7) and luminal B subtype (HR+ HER2-high Ki67) (HR 4.4, 95% CI 1.6-12.3). PABC showed different biologic features than non-PABC. PABC had a particularly poor prognosis in the luminal B (HR+ HER2-highKi67) and HER2 subtypes. To improve the prognosis of PABC, treatment should be considered according to subtype. Development of drugs that can be used during pregnancy is needed.