BACKGROUNDTo investigate the clinicopathological significance of c-kit protein expression in small cell lung cancer (SCLC).

METHODSc-kit protein expression was detected in 52 formalin-fixed and paraffin-embedded SCLC, 20 non-small cell lung cancer (NSCLC) and 10 normal lung tissues by immunohistochemistry with rabbit antibody to human c-kit protein.

RESULTSc-kit protein was expressed in 61.5% (32/52) of primary SCLC, but negative in all 20 samples of NSCLC and 10 normal lung tissues. c-kit protein was localized in cytoplasm of cancer cells. The expression of c-kit protein was related to tumor size ( P =0.010) and prognosis ( P =0.000 1), but not to sex ( P =0.208), age ( P =1.000) or TNM stage ( P =0.722) of SCLC.

CONCLUSIONSc-kit protein expression may be corresponding to the prognosis of SCLC. Since in situ detection of c-kit protein is more direct than the other methods, it is helpful to clinicopathological diagnosis, targeted therapies interacting with c-kit signaling pathway and prognostic assessment in SCLC.