Multilevel analysis is an appropriate and powerful tool for analyzing hierarchical structure data widely applied from public health to genomic data. In practice, however, we may lose the information on multiple nesting levels in the multilevel analysis since data may fail to capture all levels of hierarchy, or the top or intermediate levels of hierarchy are ignored in the analysis. In this study, we consider a multilevel linear mixed effect model (LMM) with single imputation that can involve all data hierarchy levels in the presence of missing top or intermediate-level clusters. We evaluate and compare the performance of a multilevel LMM with single imputation with other models ignoring the data hierarchy or missing intermediate-level clusters. To this end, we applied a multilevel LMM with single imputation and other models to hierarchically structured cohort data with some intermediate levels missing and to simulated data with various cluster sizes and missing rates of intermediate-level clusters. A thorough simulation study demonstrated that an LMM with single imputation estimates fixed coefficients and variance components of a multilevel model more accurately than other models ignoring data hierarchy or missing clusters in terms of mean squared error and coverage probability. In particular, when models ignoring data hierarchy or missing clusters were applied, the variance components of random effects were overestimated. We observed similar results from the analysis of hierarchically structured cohort data.

PURPOSE: We evaluated the effect of local recurrence (LR) and regional recurrence (RR) on distant metastasis and survival in patients treated with breast conservation therapy (BCT). METHODS: We analyzed 907 patients who were treated for invasive breast cancer between 1993 and 2006. With 53 months of follow-up, 28 patients (3.1%) developed LR in the breast and 12 patients (1.3%) developed RR before distant metastasis. LR and RR were separated into four patterns to determine the prognostic relevance of recurrence site and time to recurrence: LR within 3 years (early LR), LR after 3 years (late LR), RR within 3 years (early RR), and RR after 3 years (late RR). RESULTS: Early LR (hazard ratio [HR], 4.76; p=0.003) and early RR (HR, 18.16; p<0.001) were independent predictors of distant metastasis. In terms of overall survival, early LR (HR, 5.24; p=0.002), and early RR (HR, 18.80; p<0.001) were significantly related with poor survival. Patients with late LR/RR had a similar favorable prognosis compared with patients who never experienced LR/RR. CONCLUSION: The result suggests that time to LR/RR following BCT is a significant predictor developing a distant metastasis and surviving.
Breast ; Breast Neoplasms ; Follow-Up Studies ; Humans ; Neoplasm Metastasis ; Prognosis ; Recurrence

PURPOSE: Breast conservation surgery (BCS) has become a standard treatment method for patients with early breast cancer. Endoscopy-assisted BCS (EABCS) can be performed through an inconspicuous periareolar and a small axillary incision for sentinel node biopsy, which may give better cosmetic outcomes than conventional BCS skin incisions. This study was designed to evaluate the feasibility of EABCS for patients with early breast cancer. METHODS: Forty-three patients were candidates for EABCS, and EABCS was performed in 40 patients with breast cancer between January 2008 and July 2010. Their clinicopathological features were retrospectively analyzed. Operative time, margin status, complications, and relapse-free survival were compared with those of patients treated by conventional BCS and who were treated at the same institute during the same period. RESULTS: The most common lesion site of the EABCS and conventional BCS groups was the upper area of the breast. Tumor size in all patients was less than 4 cm (range, 0.4-3.7 cm), and nodal involvement was found in eight (20%) patients in the BCS group. The mean operative time was 110 minutes for the EABCS group and 107 minutes for the conventional BCS group, and those were not significantly different. No significant difference in frozen or final margin status was observed between the EABCS and conventional BCS groups. Relapse-free survival was statistically equivalent between the groups with a median follow-up of 12 months. Postoperative complications occurred in five cases in four patients with EABCS, which was not significantly different from conventional BCS. CONCLUSION: Performing EABCS in patients with early breast cancer seems to be feasible and safe. Further study with a longer-term follow-up may be needed to confirm the clinical value of EABCS.
Biopsy ; Breast ; Breast Neoplasms ; Cosmetics ; Endoscopy ; Follow-Up Studies ; Humans ; Mastectomy, Segmental ; Nitriles ; Operative Time ; Postoperative Complications ; Pyrethrins ; Retrospective Studies ; Skin ; Survival Rate

PURPOSE: The purpose of the study was to evaluate the effect of preoperative magnetic resonance imaging (MRI) on survival outcomes for breast cancer. METHODS: A total of 954 patients who had T1–2 breast cancer and received breast-conserving therapy (BCT) between 2007 and 2010 were enrolled. We divided the patients according to whether they received preoperative MRI or not. Survival outcomes, including locoregional recurrence-free survival (LRRFS), recurrence-free survival (RFS), and overall survival (OS), were analyzed. RESULTS: Preoperative MRI was performed in 743 of 954 patients. Clinicopathological features were not significantly different between patients with and without preoperative MRI. In the univariate analyses, larger tumors were marginally associated with poor LRRFS compared to smaller tumors (hazard ratio [HR], 3.22; p=0.053). Tumor size, histologic grade, estrogen receptor (ER), progesterone receptor (PR), hormonal therapy, and adjuvant chemotherapy status were associated with RFS. Larger tumor size, higher histologic grade, lack of ER and PR expression, and no hormonal therapy were associated with decreased OS. Tumor size was associated with LRRFS in the multivariate analyses (HR, 4.19; p=0.048). However, preoperative MRI was not significantly associated with LRRFS, RFS, or OS in either univariate or multivariate analyses. CONCLUSION: Preoperative MRI did not influence survival outcomes in T1–2 breast cancer patients who underwent BCT. Routine use of preoperative MRI in T1–2 breast cancer may not translate into longer RFS and OS.
Breast Neoplasms* ; Breast* ; Chemotherapy, Adjuvant ; Estrogens ; Humans ; Magnetic Resonance Imaging* ; Mastectomy, Segmental ; Multivariate Analysis ; Receptors, Progesterone

PURPOSE: The optimum local surgical strategy regarding breast-conserving therapy (BCT) for triple-negative breast cancer (TNBC) is controversial. To investigate whether BCT is appropriate for patients with TNBC, we evaluated the clinical outcomes of BCT in women with TNBC compared to those of women without TNBC, using a large, single-center cohort. MATERIALS AND METHODS: We performed a retrospective analysis of 1533 women (TNBC n=321; non-TNBC n=1212) who underwent BCT for primary breast cancer between 2000 and 2010. Clinicopathological characteristics, locoregional recurrence-free survival (LRFS), and overall survival (OS) were analyzed. RESULTS: Tumors from the TNBC group had a higher T stage (T2 37.4% vs. 21.0%, p<0.001), a lower N stage (N0 86.9% vs. 75.5%, p<0.001), and a higher histologic grade (Grade III 66.8% vs. 15.4%, p<0.001) than the non-TNBC group. There were no differences in 5-year LRFS rates between the TNBC and non-TNBC groups (98.7% vs. 97.8%, p=0.63). The non-TNBC group showed a slightly better 5-year OS than the TNBC group; however, the difference was not significant (96.2% vs. 97.3%, p=0.72). In multivariate analyses, TNBC was not associated with poor clinical outcomes in terms of LRFS and OS [hazard ratio (HR) for LRFS=0.37, 95% confidence interval (CI): 0.10-1.31; HR for OS=1.03, 95% CI: 0.31-3.39]. CONCLUSION: TNBC patients who underwent BCT showed non-inferior locoregional recurrence compared to non-TNBC patients with BCT. Thus, BCT is an acceptable surgical approach in patients with TNBC.
Adult ; Aged ; Breast Neoplasms/mortality/pathology/*surgery ; Disease-Free Survival ; Female ; Humans ; *Mastectomy, Segmental ; Middle Aged ; *Neoplasm Recurrence, Local/mortality/pathology ; Proportional Hazards Models ; Retrospective Studies ; Time Factors ; Treatment Outcome ; Triple Negative Breast Neoplasms/mortality/pathology/*surgery

PURPOSE: To investigate clinicopathological characteristics and outcomes of male breast cancer (MBC). PATIENTS AND METHODS: We retrospectively analyzed the data of 20 MBC patients in comparison with female ductal carcinoma treated at Yonsei University Severance Hospital from July 1985 to May 2007. Clinicopathological features, treatment patterns, and survival were investigated. RESULTS: MBC consists of 0.38% of all breast cancers. The median age was 56 years. The median symptom duration was 10 months. The median tumor size was 1.7cm, 27.8% showed node metastasis, and 71.4% were estrogen receptor positive. All 20 cancers were arisen from ductal cells. No lobular carcinoma was found. The incidence of stages 0, I, II, and III in patients were 2, 10, 4, and 3, respectively. All patients underwent mastectomy. One with invasive cancer did not receive axillary node dissection and stage was not exactly evaluated. Adjuvant treatments were determined by pathologic parameters and stage. Clinicopathological parameters and survival rates of MBC were comparable to those of female ductal carcinoma. CONCLUSION: The onset age of MBC was 10 years older and symptom duration was longer than in female patients. No difference in outcomes between MBC and female ductal carcinoma suggests that the biology of MBC is not different from that of females. Therefore, education, an appropriate system for early detection, and adequate treatment are necessary for improving outcomes.
Adult ; Aged ; Breast Neoplasms/mortality/pathology/therapy ; Breast Neoplasms, Male/mortality/*pathology/therapy ; Carcinoma, Ductal, Breast/mortality/pathology/therapy ; Disease-Free Survival ; Female ; Humans ; Korea/epidemiology ; Male ; Middle Aged ; Retrospective Studies ; Survival Rate ; Young Adult

Clinicopathological characteristics and prognostic factors of mucinous carcinoma (MC) were compared with invasive ductal carcinoma-not otherwise specified (IDC-NOS). Clinicopathological characteristics and survivals of 104 MC patients were retrospectively reviewed and compared with those of 3,936 IDC-NOS. The median age at diagnosis was 45 yr in MC and 47 yr in IDC-NOS, respectively. The sensitivity of mammography and sonography for pure MC were 76.5% and 94.7%, respectively. MC showed favorable characteristics including less involvement of lymph node, lower stage, more expression of estrogen receptors, less HER-2 overexpression and differentiated grade, and better 10-yr disease-free survival (DFS) and overall survival (OS) (86.1% and 86.3%, respectively) than IDC-NOS (74.7% and 74.9%, respectively). Ten-year DFS of pure and mixed type was 90.2% and 68.8%, respectively. Nodal status and stage were statistically significant factors for survival. MC in Koreans showed similar features to Western populations except for a younger age of onset than in IDC-NOS. Since only pure MC showed better prognosis than IDC-NOS, it is important to differentiate mixed MC from pure MC. Middle-aged Korean women presenting breast symptoms should be examined carefully and evaluated with an appropriate diagnostic work-up because some patients present radiologically benign-like lesions.
Adenocarcinoma, Mucinous/diagnosis/genetics/*pathology ; Adult ; Aged ; Aged, 80 and over ; Breast/pathology ; Breast Neoplasms/classification/diagnosis/genetics/*pathology ; Carcinoma, Ductal/diagnosis/genetics/*pathology ; Disease-Free Survival ; Female ; Genes, erbB-2 ; Humans ; Korea ; Lymphatic Metastasis ; Mammography ; Middle Aged ; Prognosis ; Retrospective Studies ; Sensitivity and Specificity ; Survival Rate ; Young Adult

PURPOSE: During a sentinel lymph node biopsy (SLNB) for breast cancer, the appropriate number of sentinel lymph nodes (SLNs) to be removed for accurate axillary staging is still controversial. We hypothesized that there might be an optimal threshold number of SLNs. We investigated how many SLNs should be removed to achieve an acceptable accuracy and ensure minimal morbidity. METHODS: We reviewed data of 328 patients with invasive breast cancer who underwent SLNB followed by complete level I and II axillary dissection between January 2004 and December 2005. The false negative rate (FNR) and accuracy of SLNB according to the number of removed SLNs were evaluated. RESULTS: The mean number of SLNs removed was 3.0 (range, 1-14), and that of total retrieved axillary lymph nodes was 17.5 (range, 10-40). In total, 111 (33.8%) patients had positive nodes on the permanent pathological report. Among them, 12 patients had negative SLNs; thus, the overall FNR of SLNB was 10.8% (12/111) and the accuracy was 96.3% (316/328). The FNR was 26.6% for a single SLN, 8.0% for two, and 11.1% for three. In cases where four or more SLNs were removed, the FNR decreased to 0% and accuracy reached 100%. CONCLUSION: Our data suggest that a SLNB should not only remove one or two of the hottest node(s) when other hot nodes exist. We also suggest that four might be an optimal threshold number of SLNs to be removed and that removal of more than four SLNs does not improve axillary staging accuracy.
Breast ; Breast Neoplasms ; Dietary Sucrose ; Humans ; Lymph Nodes ; Nitriles ; Pyrethrins ; Sentinel Lymph Node Biopsy

PURPOSE: Apocrine carcinoma is a rare type of breast carcinoma, which has not been fully investigated. The aim of this study was to review clinicopathological features of apocrine carcinoma of the breast and to determine if there are some characteristics different from invasive ductal carcinoma. METHODS: There were 4,064 breast cancer patients who had been managed in the Department of Surgery of Yonsei University College of Medicine from January 1997 to January 2008. Out of the patients, 16 patients with apocrine carcinoma and 2,997 patients with invasive ductal carcinoma were analyzed retrospectively. RESULTS: The incidence of apocrine carcinoma was 0.4%. Most of the clinicopathologic features of apocrine carcinoma were similar to those of invasive ductal carcinoma. The percentage of estrogen receptor (ER) positivity and progesterone receptor (PR) positivity of apocrine carcinoma were all 12.5%. And the percentage of ER positivity and PR positivity of invasive ductal carcinoma were 64.2% and 55.2% respectively. Androgen receptor was only examined for eleven patients out of the 16 patients with apocrine carcinoma and the result were all positive. CONCLUSION: Apocrine carcinoma is also a rare disease in Korea. When compared with invasive ductal carcinoma, the disease did not appear to show any other significant difference in clinicopathologic characteristics but the percentages of ER and PR positivity of apocrine carcinoma seemed lower than those of invasive ductal carcinoma.
Breast ; Breast Neoplasms ; Carcinoma, Ductal ; Estrogens ; Humans ; Incidence ; Korea ; Rare Diseases ; Receptors, Androgen ; Receptors, Progesterone ; Retrospective Studies

PURPOSE: Papillary carcinoma of the breast is a rare disease and accounts for 1-2% of all breast cancers. Because of its rarity, there have been no reports regarding prognostic factors of papillary carcinoma of the breast. The aim of this study was to review the clinicopathological factors and treatment modalities of papillary carcinoma of the breast and to evaluate the relationship between these factors and survival rates. METHODS: We retrospectively analyzed 31 patients diagnosed with papillary carcinoma of the breast from January 1986 to December 2005. RESULTS: The mean age of the patients was 53.5 yr. The most common symptom was a palpable mass (n=27). The mean size of a tumor was 3.5 cm and 41.9% of the patients were categorized as T2. Eighteen patients had node negative breast cancer. According to the TNM stage, there were 5, 5, 16 and 2 patients with stage 0, I, II and III disease, respectively. Expression of estrogen receptor and progesterone receptor were positive in 80.8% and 69.2% of the patients, respectively. Twenty-three patients underwent mastectomy and eight patients underwent breast-conserving surgery. Fourteen patients received chemotherapy, 20 patients received hormone therapy, and 10 patients received radiotherapy. The 10-yr disease-free survival rate and 10-yr overall survival rate were 74.9% and 86.1%, respectively. Axillary lymph node negative and an age under 50 yr were statistically significant factors in 5-yr disease-free survival and in 5-yr overall survival, respectively. CONCLUSION: Papillary carcinoma of the breast showed a favorable outcome. Lymph node status and age were statistically significant factors for survival rates. The tumor size and stage had a relation with the survival rate, although the relation was not statistically significant.
Breast ; Breast Neoplasms ; Carcinoma, Papillary ; Disease-Free Survival ; Estrogens ; Humans ; Lymph Nodes ; Mastectomy ; Mastectomy, Segmental ; Prognosis ; Rare Diseases ; Receptors, Progesterone ; Retrospective Studies ; Survival Rate