CD117 (c-KIT) overexpression in patients with extensive-stage small-cell lung carcinoma

The aim of this study was to determine the incidence and role of CD117 (c-KIT) overexpression as a predictive/prognostic marker in extensive-stage small-cell lung carcinoma (ESSCLC). We performed a retrospective study on subjects with a biopsy-proven diagnosis of ESSCLC.

A chart review for demographic and clinical data was performed on patients with ESSCLC diagnosed between 1991 and 2001. CD117 overexpression was evaluated using immunohistochemistry (A4052 polyclonal antibody) performed on archival paraffin-embedded specimens.

Two hundred and twenty-three patients with ESSCLC were identified, of whom 193 (84 females, 109 males) with a mean age of 68.5 years (range 42-90) had adequate tissue specimens available for CD117 testing. The most commonly presenting symptom was weight loss, seen in 61 patients (31.6%). Of the 193 specimens, 54 (27.9%) showed CD117 overexpression. The median length of survival for CD117-positive patients was 9 months as compared with the CD117-negative population, in whom the survival was 6 months (P = 0.025, Cox proportional hazard method).

CD117 overexpression detected using immunohistochemistry is observed in about a third of patients with ESSCLC and does not have statistically significant prognostic value. However, CD117 may be a potential target for site-specific immunotherapy in ESSCLC. Our findings suggest a role for clinical trials assessing the role of selective tyrosine kinase inhibitor STI-571 (alone or in combination with conventional therapy) in patients with ESSCLC.