Study design: This retrospective study compared the expression of cancer stem cell surface marker CD44v9⁺ and proliferation of CD44⁺ cancer cells in patients treated with sulfasalazine in long-term or short-term therapy.

Results: CD44v9⁺ expression and median proportion of proliferating CD44v9⁺ were decreased in the long-term treated group  compared to the short-term group as shown by immunohistochemical analysis.

Conclusions: Proliferation of CD44v9⁺ cells is reduced by long-term sulfasalazine administration, suggesting sulfasalazine as a new potential therapeutic agent targeting CD44v9⁺ cells.