Aldehyde dehydrogenase 1 expression in inflammatory breast cancer as measured by immunohistochemical staining

Inflammatory breast cancer (IBC) is a rare but aggressive type of breast carcinoma. Despite multimodality approaches, the clinical outcome of patients with IBC remains poor. Tumors arising from cancer stem cells (CSCs) are associated with drug resistance, tumor recurrence, and poor prognosis. This study aimed to evaluate expression of aldehyde dehydrogenase 1 (ALDH1), a putative stem cell marker, in IBC tumors.

Tissue microarrays of 74 surgically resected IBC tumors were immunohistochemically stained for ALDH1. The results were correlated with clinicopathologic parameters and survival data and were compared with findings published in the literature.

The median follow-up time of the cohort was 42.1 months, and the 5-year overall survival (OS) rate was 46%. Twenty-four tumors (32%) were positive for ALDH1 staining. However, ALDH1 expression was not significantly associated with clinicopathologic variables, including lymph node status, tumor grade, and the status of estrogen receptor, progesterone receptor, and human epidermal growth factor receptor 2. Log-rank testing found that ALDH1 expression was not significantly associated with the OS rate, although there was a trend toward an association with lower OS rate (P = .07). The findings were consistent with some of the published data, but substantial inconsistency among reports was noted.

In this IBC cohort, no significant correlation between ALDH1 expression and prognosis or other clinicopathologic variables was found. Although sample size and selection criteria may be contributory factors, inconsistent results reported in the literature raise concern regarding the reliability of immunohistochemically identified ALDH1 as a sole marker of breast CSCs. Further study is required to elucidate the significance of CSCs in IBC biology.