Cancer stem cells are defined as focal cluster of cells within a tumor that possess the capacity for self-renewal and differentiation into phenotypically heterogeneous cells. Cluster of differentiation 44 (CD44) is considered one of the gastric cancer stem cell markers. We aimed to investigate how the expression of CD44 varies according to the clinicopathologic characteristics in gastric cancer.

For this study, 157 patients who received an operation due to gastric cancer between May 1998 and December 2009 were selected. CD44 immunohistochemistry was reviewed using the semi-quantitative scoring of intensity and proportion. The sum of the intensity and proportion scores was calculated, and a score of 2 or less was deemed ‘CD44-negative’ and 3 or more as ‘CD44-positive.’

Among the final 143 subjects, 69 (48.3%) were CD44 positive. Older age, intestinal type gastric cancer, lymphatic invasion, and lymph node metastasis were significantly correlated with expression of CD44. In the multivariate analysis, older age was the only independent factor associated with CD44 expression (P=0.028). CD44 expression was correlated with overall survival, 5-year survival, and disease-free survival. In the multivariate analysis, older age, male gender, and lymphatic invasion were independent predictors of poor overall survival. Also, older age and lymphatic invasion were significant factors in 5-year survival, and lymphatic invasion was an independent factor of poor disease-free survival.

Older age (≥60 years) was independently associated with CD44 expression in gastric cancer patients. Also, CD44 expression was correlated with poor prognosis in gastric cancer patients.