Stage Information for Salivary Gland Cancer
In general, tumors of the major salivary glands are staged according to size, extraparenchymal extension, lymph node involvement (in parotid tumors, whether or not the facial nerve is involved), and presence of metastases.[1,2,3,4] Tumors arising in the minor salivary glands are staged according to the anatomic site of origin (e.g., oral cavity and sinuses).
Clinical stage, particularly tumor size, may be the critical factor to determine the outcome of salivary gland cancer and may be more important than histologic grade.[5,6] Diagnostic imaging studies may be used in staging. With excellent spatial resolution and superior soft tissue contrast, magnetic resonance imaging (MRI) offers advantages over computed tomographic scanning in the detection and localization of head and neck tumors. Overall, MRI is the preferred modality for evaluation of suspected neoplasms of the salivary glands.
Definitions of TNM
The American Joint Committee on Cancer (AJCC) has designated staging by TNM classification to define salivary gland cancer.
Table 1. Primary Tumor (T)a
|a Reprinted with permission from AJCC: Major salivary glands (parotid, submandibular, and sublingual) . In: Edge SB, Byrd DR, Compton CC, et al., eds.: AJCC Cancer Staging Manual. 7th ed. New York, NY: Springer, 2010, pp 79-86.|
|b Extraparenchymal extension is clinical or macroscopic evidence of invasion of soft tissues. Microscopic evidence alone does not constitute extraparenchymal extension for classification purposes.|
|TX||Primary tumor cannot be assessed.|
|T0||No evidence of primary tumor.|
|T1||Tumor ≤2 cm in greatest dimension without extraparenchymal extension.b|
|T2||Tumor >2 cm but ≤4 cm in greatest dimension without extraparenchymal extension.b|
|T3||Tumor >4 cm and/or tumor having extraparenchymal extension.b|
|T4a||Moderately advanced disease.|
|Tumor invades skin, mandible, ear canal, and/or facial nerve.|
|T4b||Very advanced disease.|
|Tumor invades skull base and/or pterygoid plates and/or encases carotid artery.|