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

Abstract

This study aimed to investigate the clinicopathologic features and subtype distribution of invasive breast cancer in elderly women (≥70 years of age). 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). 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. 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.