Decreased survival in patients with CD44-negative typical bronchial carcinoid tumors

Tumor tissues from 43 patients with typical bronchial carcinoids have been immunostained with monoclonal antibodies (mAbs) against the standard form (CD44s) and the splice variants v4, v5, v6, v7, v7-8, v9 and v10 of the adhesion molecule CD44. The staining results were correlated with clinical data. Ten patients (23%) had regional lymph node metastases at diagnosis. Distant metastases have occurred in 12% of the patients; 9% died during the observation period of median 65 months (14-325). Positive staining for CD44s was correlated with decreased risk for distant metastases and disease related death. All patients with distant metastases were v6-negative. Patients with CD44v7-8-positive tumors had decreased risk for distant metastases, but the differences in mortality did not reach statistical significance. CD44v9 correlated significantly with decreased risk for distant metastases and death. The remaining CD44 variants (v4, v5 and v10) did not correlate significantly with clinical outcome. Our results confirm earlier observations that typical bronchial carcinoids are potentially malignant. However, positive staining for CD44s, v7-8 and v9 seems to be associated with a more favorable outcome, and may be taken into consideration in prognostic evaluation.