Patterns of treatment failure in salivary gland cancers

The purpose of the study was to publish our experience of salivary gland cancer treatment with large number of patients treated at a single institution.

Salivary gland cancers are rare tumors of the head and neck representing about 5% of cancers in that region and about 0.5% of all malignancies. Due to the rarity of the disease, most of the studies regarding treatment outcome consist of low number of patients, thus making it difficult to draw conclusions.

115 patients with primary salivary gland cancer were included in a retrospective study. The subsites of tumor were the parotid gland (58% patients), submandibular gland (19%) and minor salivary glands (23%). All patients underwent primary surgical resection. The following were collected: age, stage of the disease, T status, N status, grade of tumor, perineurial invasion, lymphovascular invasion, extracapsular spread, final histological margin status and postoperative treatment. Details of local, regional or distant recurrence, disease free survival and overall survival were included.

The majority (65%) of patients presented in early stage, T1 and T2 tumors. 81% of patients were N0. Free surgical margins were achieved in 18% of patients, close in 28% patients and positive surgical margins in 54% (62) patients. Factors that significantly increased the risk of recurrence: T stage (p = 0.0006); N-positive status (p < 0.0001); advanced stage of the disease (p < 0.0001); high grade of tumor (p = 0.0007); PNI (p = 0.0061); LVI (p = 0.0022); ECS (p = 0.0136); positive surgical margins (p = 0.0022). On multivariate analysis, high grade of tumor and positive surgical margins remained significant independent adverse factors for recurrence formation.

This report shows a single institution results of oncological treatment in patients with malignant salivary gland tumors, where positive surgical margins strongly correlate with patients' worse outcome. Whether to extend the procedure, which very often requires sacrificing the nerve is still a question of debate.