Prognostic value of expression of molecular markers in adenoid cystic cancer of the salivary glands compared with lymph node metastasis: a retrospective study.

Background: Adenoid cystic cancer arising in the salivary glands has distinctive features such as perineural invasion, distant metastasis, and a variable prognosis. In salivary gland cancer, c-kit, EGFR, and VEGF are representative molecular markers that may predict remnant and recurrent tumors. In this study, the expression of c-kit, EGFR, and VEGF in adenoid cystic cancer was evaluated, and the relationships between the expression of these markers and the clinical findings were investigated.
Methods: The medical records of 48 patients who were treated for parotid adenoid cystic cancer from January 1990 to January 2006 were reviewed. The tumor location, size, histological subtypes, perineural invasion, the resected margin status, and lymph node metastasis were assessed. Immunohistochemical staining and semiquantitative analysis of c-kit, EGFR and VEGF were performed. The relationship between the expression of each marker and the clinicopathological factors were analyzed.
Results: Positive c-kit immunostaining was present in 45 patients (94%), with weak positivity (+1) in 23, moderate positivity (+2) in 19 and strong positivity (+3) in three. Positive EGFR immunostaining was observed in 27 (56%), with weak positivity (+1) in 19 and moderate positivity (+2) in eight with no strong positive staining. Positive VEGF immunostaining was present in 42 patients (88%) with weak positivity (+1) in 12, moderate positivity (+2) in 17, and strong positivity (+3) in 13. Only the expression of VEGF was significantly higher in parotid gland tumors than in any other gland (P = 0.032). Marginal involvement was associated with strong VEGF expression (P = 0.02). No marker was significantly correlated with recurrence or the survival rate. Lymph node status was related to the survival rate.
Conclusions: The expression of c-kit, EGRF, and VEGF had no predictive value for recurrence or the prognosis of adenoid cystic cancer. Only the lymph node status was related to the prognosis.