The value of insulin-like growth factor-1 receptor for predicting early glottic carcinoma response to radiotherapy.

OBJECTIVE

The optimal management of laryngeal carcinoma requires tumor treatment and preservation of laryngeal functions, such as swallowing and voice quality. Radiotherapy (RT) can fulfill both criteria, although it remains important to identify predictors of radioresistance and reduce unnecessary irradiation. Insulin-like growth factor-1 receptor (IGF-1R) is a transmembrane receptor that plays a key role in cancer development, although its prognostic value after RT remains unknown. We evaluated the predictive value of IGF-1R expression for RT response in patients with early glottic squamous cell carcinoma.

METHODS

We retrospectively reviewed 43 patients with T1N0 and T2N0 glottic squamous cell carcinoma who were treated with RT alone. Biopsy specimens were stained using an anti-IGF-1R antibody, and we evaluated the relationships between IGF-1R expression and T classification or tumor recurrence. We also evaluated the loco-regional control (LRC) rate and the prognostic value of various clinical factors.

RESULTS

All cases achieved complete response after the initial RT, and 10 (23.3%) patients experienced local tumor recurrence. Twenty-five patients (58.1%) exhibited high IGF-1R expression, although the level of IGF-1R expression was not correlated with T classification. Local recurrence was observed in 36% (9/25) of patients with high IGF-1R expression and in only 5% (1/18) of patients with low IGF-1R expression (p<0.05). The 2-year LRC rate was 94.1% for the low IGF-1R expression group, compared to 49.8% for the high IGF-1R expression group (p=0.04). Anterior commissure involvement and IGF-1R expression were independent adverse factors for LRC.

CONCLUSION

High IGF-1R expression was more common among patients with recurrent early glottic carcinoma, which suggests that there is a biological relationship between IGF-1R expression and RT response. Thus, IGF-1R may be a useful screening parameter for RT response in laryngeal carcinoma.