Purpose: Although breast cancer is known to show a left predominance, the clinical characteristics and causes underlying this finding remain unclear. In addition, no related studies on breast cancer laterality have been conducted in patients with breast cancer in Korea. Therefore, we aimed to analyze differences in breast cancer laterality and the associated clinicopathological characteristics and prognosis among Korean patients with breast cancer. Methods: We conducted a retrospective analysis using large-scale data on clinicopathological factors and prognosis differences related to breast cancer laterality from the Korean Breast Cancer Society Registration system. The left-to-right ratio (LRR) of breast cancer was calculated through binomial distribution, and factors related to breast cancer laterality were identified through logistic regression analysis. In addition, the differences in the survival rates for left and right breast cancers were analyzed using the Kaplan-Meier method and Cox proportional hazards model. Results: In 171,500 patients, the LRR was 1.031 (95% confidence interval, 1.022–1.041; P < 0.001). Multivariate analysis showed that the ratio of left breast cancer was related to age, body mass index (BMI), location, and human epidermal growth factor receptor 2 (HER2) status. The survival rate of patients with left and right breast cancers showed no significant difference. Conclusion A large-scale analysis revealed a left predominance in breast cancer laterality in Korean patients. Over time, this predominance gradually decreased. Age, BMI, location, and HER2 status affected breast cancer laterality. However, while left breast cancer showed relatively aggressive characteristics, it was not associated with a difference in the survival rate.

Purpose: We investigated the treatment response and prognosis using the neutrophil-tolymphocyte ratio (NLR) and standardized uptake value (SUV) of 18F-fluorodeoxyglucose positron emission tomography ( 18F-FDG PET) in neoadjuvant settings. Methods: Baseline NLR and maximum SUV (SUVmax ) were retrospectively analyzed in 273 females with breast cancer who received neoadjuvant chemotherapy followed by surgery.Of these, 101 patients underwent 18F-FDG PET after 3–4 neoadjuvant chemotherapy cycles, which allowed the measurement of ΔSUVmax , an early reduction in SUVmax . NLR and early SUVmax reduction (ΔSUVmax) were classified as low and high, respectively, relative to the median values. Results: The mean NLR was lower, and the mean ΔSUVmax was higher in patients with pathologic complete response (pCR) than in those with residual tumors. The ΔSUVmax was an independent variable associated with pCR. Furthermore, the high NLR group had poor recurrence-free survival (RFS) and overall survival. Among patients with ΔSUVmax data, high NLR (adjusted hazard ratio, 2.82; 95% confidence intervals [CI], 1.26–6.28; P = 0.016) and low ΔSUVmax (adjusted hazard ratio, 2.39; 95% CI, 1.07–5.34; P = 0.037) were independent prognostic factors for poor RFS. The categorization of the patients into four groups according to the combination of NLR and ΔSUVmax showed that patients with high NLR and low ΔSUVmax had significantly poorer RFS. Conclusion Baseline NLR and ΔSUVmax were significantly associated with the prognosis of patients with breast cancer who received neoadjuvant chemotherapy. These results suggest that metabolic non-responders with defective immune systems have worse survival outcomes.

By investigating the characteristics and prognosis of breast cancer (BC) patients who have undergone hormone replacement therapy (HRT), this study addresses a gap in the existing literature. A total of 17,355 postmenopausal patients with BC were analyzed using data from the Korea Breast Cancer Society database (2000–2014). Among them, 3,585 (20.7%) had a history of HRT before BC diagnosis (HRT group), while 13,770 (79.3%) never received HRT (non-HRT group). The HRT group exhibited an earlier pathologic stage, lower histologic and nuclear grades, and a higher rate of breast conservation surgery compared to the non-HRT group. Furthermore, this group had a higher rate of screening participation and a greater proportion of patients with a normal or overweight body mass index (BMI). The prognosis of the HRT group was better than that of the non-HRT group, with a 5-year overall survival rate of 93.9% versus 91.7% (p < 0.001). The hazard ratio for the HRT group was 0.7 (95% confidence interval, 0.608–0.805; p < 0.001). Increased screening participation, longer HRT duration, and a normal or overweight BMI were associated with a better prognosis in the HRT group. Patients with BC who underwent HRT showed better clinicopathological characteristics and prognosis than those who did not receive HRT. The results highlighted significant differences in patients who underwent screening and those with a normal or overweight BMI. Furthermore, a longer HRT duration was associated with a better prognosis.

By investigating the characteristics and prognosis of breast cancer (BC) patients who have undergone hormone replacement therapy (HRT), this study addresses a gap in the existing literature. A total of 17,355 postmenopausal patients with BC were analyzed using data from the Korea Breast Cancer Society database (2000–2014). Among them, 3,585 (20.7%) had a history of HRT before BC diagnosis (HRT group), while 13,770 (79.3%) never received HRT (non-HRT group). The HRT group exhibited an earlier pathologic stage, lower histologic and nuclear grades, and a higher rate of breast conservation surgery compared to the non-HRT group. Furthermore, this group had a higher rate of screening participation and a greater proportion of patients with a normal or overweight body mass index (BMI). The prognosis of the HRT group was better than that of the non-HRT group, with a 5-year overall survival rate of 93.9% versus 91.7% (p < 0.001). The hazard ratio for the HRT group was 0.7 (95% confidence interval, 0.608–0.805; p < 0.001). Increased screening participation, longer HRT duration, and a normal or overweight BMI were associated with a better prognosis in the HRT group. Patients with BC who underwent HRT showed better clinicopathological characteristics and prognosis than those who did not receive HRT. The results highlighted significant differences in patients who underwent screening and those with a normal or overweight BMI. Furthermore, a longer HRT duration was associated with a better prognosis.

By investigating the characteristics and prognosis of breast cancer (BC) patients who have undergone hormone replacement therapy (HRT), this study addresses a gap in the existing literature. A total of 17,355 postmenopausal patients with BC were analyzed using data from the Korea Breast Cancer Society database (2000–2014). Among them, 3,585 (20.7%) had a history of HRT before BC diagnosis (HRT group), while 13,770 (79.3%) never received HRT (non-HRT group). The HRT group exhibited an earlier pathologic stage, lower histologic and nuclear grades, and a higher rate of breast conservation surgery compared to the non-HRT group. Furthermore, this group had a higher rate of screening participation and a greater proportion of patients with a normal or overweight body mass index (BMI). The prognosis of the HRT group was better than that of the non-HRT group, with a 5-year overall survival rate of 93.9% versus 91.7% (p < 0.001). The hazard ratio for the HRT group was 0.7 (95% confidence interval, 0.608–0.805; p < 0.001). Increased screening participation, longer HRT duration, and a normal or overweight BMI were associated with a better prognosis in the HRT group. Patients with BC who underwent HRT showed better clinicopathological characteristics and prognosis than those who did not receive HRT. The results highlighted significant differences in patients who underwent screening and those with a normal or overweight BMI. Furthermore, a longer HRT duration was associated with a better prognosis.