Differences in clinicopathologic features and subtype distribution of invasive breast cancer between women older and younger than 40 years

OBJECTIVES: We investigated and compared clinicopathologic features and subtype distribution of invasive breast cancer among women <40 and ≥40 years of age. METHODS: We retrospectively compared clinicopathologic characteristics and subtype distribution of invasive breast cancer in women <40 and ≥40 years of age, in a cohort of 1,130 patients. Subtypes included luminal A (positive for hormone receptors [HR]—estrogen receptor [ER] and/or progesterone receptor [PR]—and negative for human epidermal growth factor receptor 2 [HER2] with low Ki67), luminal B (HER2(–)) (HR(+)/HER2(–)/Ki67(High)), luminal B (HER2(+)) (HR(+)/HER2(+)), HER2-overexpressing (HR(–)/HER2(+)), and triple negative (ER(–)/PR(–)/HER2(–)). RESULTS: Breast cancers in younger women had unfavorable clinicopathologic characteristics, including larger tumors and more frequent node involvement. Subtypes among the 1,130 tumors were luminal A: 36.4%, luminal B (HER2(–)): 35.0%, luminal B (HER2(+)): 7.5%, HER2-overexpressing: 7.1%, and triple negative: 14.0%. The age groups significantly differed in subtype distribution (P<0.001). Luminal A subtype was more common in the older group (38.5%) than the younger group (16.2%), and luminal B (HER2(–)) was more common in the younger group (52.2%) than in the older group (33.2%; P<0.001). CONCLUSIONS: Breast cancers in women younger than 40 years have unfavorable clinicopathologic characteristics and are more likely to be luminal B (HER2(–)) and less likely to be luminal A than breast cancers in older women

ルミナル HER2陰性乳癌において腫瘍のKi67発現は予後と負の相関を示す

藤田医科大

Differences in clinicopathologic features and subtype distribution of invasive breast cancer between elderly and non-elderly women

OBJECTIVES: This study aimed to investigate the clinicopathologic features and subtype distribution of invasive breast cancer in elderly women (≥70 years of age). METHODS: This retrospective study of 1,130 women compared the clinicopathologic characteristics and subtype distribution of invasive breast cancer in elderly (≥70 years) versus non-elderly (<70 years) women. Tumors were classified into five distinct subtypes based on the immunohistochemistry status of estrogen receptor (ER), progesterone receptor (PR), Ki67, and human epidermal growth factor receptor 2 (HER2). RESULTS: The two patient groups did not differ significantly regarding ER and HER2 status. Breast cancers in elderly women were more likely to have negative PR status (40.4% vs. 32.6%, P=0.033) and low Ki67 expression (62.0% vs. 54.4%, P=0.047) than those in non-elderly women. Elderly women were less likely to undergo axillary lymph node dissection and axillary surgery (P<0.001). Consequently, unknown node status was more common in elderly women than non-elderly women (11.1% vs. 1.4%, respectively, P<0.001), while node involvement was less common in elderly women than non-elderly women (26.9% vs. 37.7%, respectively, P<0.001). There was no significant difference in the distribution of subtypes between the two groups. CONCLUSIONS: Breast cancers in elderly women were less frequently node positive and more frequently PR negative and with low Ki67 expression than those in non-elderly women. Moreover, there was no difference in subtype distribution between the two age groups

Negative progesterone receptor status correlates with increased risk of breast cancer recurrence in luminal B HER2-positive and -negative subtypes

Objectives: The prognostic significance of the progesterone receptor (PR) has been widely investigated in luminal A and luminal B [human epidermal growth factor receptor 2 (HER2)–] breast cancer subtypes, both of which are estrogen receptor (ER)-positive and HER2-negative. In contrast, few studies have focused on PR status in luminal B (HER2+) tumors. The aim of this study was to evaluate the impact of positive PR status on outcomes in patients with luminal B (HER2–) or luminal B (HER2+) breast cancer. Methods: Survival analysis was performed to estimate the likelihood of distant recurrence and death in 469 breast cancer patients with the luminal B (HER2–) or luminal B (HER2+) subtype. The relationship between PR and HER2 status was also assessed. Results: Of 387 luminal B (HER2–) and 82 luminal B (HER2+) cancers, PR+ was significantly more frequent in the former than the latter (86.3% vs. 61.0%, respectively; P<0.001). In univariate analysis, PR was identified as a significant favorable prognostic factor for distant disease–free survival and overall survival in both subtypes, but in multivariate analysis PR was not an independent prognostic factor. Conclusions: After patients with luminal B subtype were divided into two subgroups according to HER2 status, there was evidence of a relatively good prognosis in the PR+ subgroup. Further studies with a larger number of patients are recommended to validate these findings

Inverse correlation between Ki67 expression as a continuous variable and outcomes in luminal HER2-negative breast cancer

OBJECTIVES: Few studies to date have investigated the prognostic significance of Ki67 expression as a continuous variable in breast cancer. This study aimed to evaluate the impact of Ki67 expression as a dichotomous or continuous variable on outcomes in estrogen receptor (ER)+ and human epidermal growth factor receptor 2 (HER2)– breast cancer. METHODS: Survival analysis was performed to estimate the likelihood of distant recurrence and death in retrospective data from 794 patients with ER+/HER2– breast cancer. We assessed the relationship between outcomes and two Ki67 cutoffs, 14% and 20%, and the Ki67 labeling index as a continuous variable. RESULTS: In univariate analysis, T stage, lymph node involvement, histological grade, progesterone receptor status, and Ki67 expression at the two cutoffs and as a continuous variable were identified as significant prognostic factors for distant disease-free survival (DDFS) and overall survival (OS). There were no statistical differences in DDFS and OS between women with Ki67 expression of <14% and 14–<20%. Multivariate analysis showed that Ki67 expression ≥20% was an independent prognostic indicator for DDFS. Regarding the risk of distant metastasis, the 20% cutoff was more reliable than 14%. We also found that Ki67 expression as a continuous variable was an independent prognostic factor for DDFS and OS in multivariate analyses. CONCLUSIONS: High Ki67 expression is associated with a survival disadvantage in patients with ER+/HER2– breast cancer, indicating that these patients might have a higher risk of recurrence after primary treatment and might therefore benefit from individualized treatment