Potential role of microvessel density in predicting radiosensitivity of T1 and T2 stage laryngeal squamous cell carcinoma treated with radiotherapy.

Curative radiotherapy is the first choice of therapy for T1 and T2 stage laryngeal squamous cell carcinoma (LSCC) patients to preserve their phonation. Patients with recurrent tumors who undergo salvage surgery require prolonged nasal feeding. Therefore, clinical interest has been focused on elucidating a predictive factor indicating which tumors are likely to be radiosensitive before radiotherapy. We analyzed the relations between radiosensitivity and clinicopathological factors (gender, tumor location, histological factors, and clinical tumor-node-metastasis stage), expression of apoptosis-related proteins (p53, bax, bcl-2), apoptotic index using the terminal deoxynucleotidyltransferase-mediated nick end labeling method, expression of cell proliferation-related proteins (Ki-67-labeling index and epidermal growth factor receptor overexpression) and microvessel density (MVD, vessels/field = 0.391 mm2) in biopsy specimens from 31 LSCC patients given radiotherapy (total radiotherapy dose of 52-70 Gy over 4-6.5 weeks). Univariate analysis revealed that tumors with a high MVD (> or =35 vessels/field) showed better radiosensitivity than those with a low MVD (<35 vessels/field, P = 0.008) and that a high Ki-67-labeling index (> or =40%) was weakly associated with radiosensitivity (P = 0.056). Multivariate analysis and Kaplan-Meier analysis showed that MVD alone had significant predictive power for radiosensitivity in T1 and T2 stage LSCCs after radiotherapy (P = 0.012, 0.0003, respectively). No significant association between clinicopathological factors, or of overexpression of p53, bax, bcl-2, epidermal growth factor receptor, or apoptotic index, with radiosensitivity was found. These results indicate that MVD is a potentially useful clinical factor predicting radiosensitivity for patients with early stage LSCCs before treatment.