Patient survival by Hsp70 membrane phenotype

BACKGROUND Heat shock proteins (HSPs) play important roles in tumor immunity. The authors prospectively investigated the correlation between the tumor‐specific Hsp70 membrane expression as an independent clinicopathological marker and overall survival in tumor entities that differ in their route of metastasis. METHODS Hsp70 membrane expression was examined by flow cytometry in 58 colon, 19 gastric, 54 lower rectal carcinoma, and 19 squamous cell carcinoma specimens and the corresponding normal tissues at time of first diagnosis. Kaplan‐Meier survival curves were analyzed to determine the relation of Hsp70 expression to the patients' prognosis. RESULTS An Hsp70 membrane‐positive phenotype was found in 40% (colon), 37% (gastric), 43% (lower rectal), and 42% (squamous cell) of the analyzed tumor specimens. None of the corresponding normal tissues was found to be Hsp70 membrane‐positive. In patients with colon (P = .032) and gastric (P = .045) carcinomas, an Hsp70 membrane expression correlated significantly with an improved overall survival; a negative association was seen in lower rectal (P = .085) and squamous cell carcinoma (P = .048). CONCLUSIONS The authors hypothesized that differing relations between surface expression of Hsp70 on tumor cells and clinical outcomes may reflect differences in the route of metastases. Colon and gastric carcinomas metastasize into the liver where hepatic natural killer cells may have the capacity to recognize and kill Hsp70 membrane‐positive tumor cells and thus account for a better overall survival. Cancer 2007; 110:926–35. © 2007 American Cancer Society. Membrane‐bound heat shock proteins 70 (Hsp70) acts as a positive or negative prognostic marker in different tumor entities. These findings could be explained by their different routes of metastasis. Colon and gastric carcinoma but not squamous cell and lower rectal carcinoma metastasize to the liver and, thus, might improve overall survival. It is hypothesized that liver‐residing natural killer cells provide an “immunological filter” for Hsp70 membrane‐positive tumor cells coming from the spanchnic system.