7 Major Salivary Glands (Parotid, Submandibular,
and Sublingual) 7
INTRODUCTION
This staging system is based on an extensive retrospective review of the world literature regarding malignant tumors of the major salivary glands. Numerous factors affect patient survival, including the histologic diagnosis, cellular differ- entiation of the tumor (grade), site, size, degree of fixation or local extension, facial nerve involvement, and the status of regional lymph nodes as well as distant metastases. The classification involves the four dominant clinical vari- ables: tumor size, local extension of the tumor, nodal metastasis, and distant metastasis. The T4 category has been divided into T4a and T4b. T4a indicates advanced lesions that are resectable with grossly clear margins; T4b reflects extension to areas that preclude resection with clear margins. Histologic grade, patient age, and tumor site are important additional factors that should be recorded for future analysis and potential inclusion in the staging system.
ANATOMY
Primary Site. The major salivary glands include the parotid, submandibular, and sublingual glands. Tumors arising in minor salivary glands (mucus- secreting glands in the lining membrane of the upper aerodigestive tract) are staged according to the anatomic site of origin (e.g., oral cavity, sinuses, etc.).
Primary tumors of the parotid constitute the largest proportion of salivary gland tumors. Sublingual primary cancers are rare and may be difficult to dis- tinguish with certainty from minor salivary gland primary tumors of the ante- rior floor of the mouth.
Regional Lymph Nodes. Regional lymphatic spread from salivary gland cancer is less common than from head and neck mucosal squamous cancers and varies according to the histology and size of the primary tumor. Most nodal metastases will be clinically apparent on initial evaluation.
C07.9 Parotid gland C08.0 Submandibular gland C08.1 Sublingual gland
C08.8 Overlapping lesion of major salivary glands
C08.9 Major salivary gland, NOS
SUMMARY OF CHANGES
• In order to maintain internal consistency of T staging across all sites, the descrip- tion for T3 has been revised. In addition to tumors having extraparenchymal extension, all tumors larger than 4 cm are considered T3.
• T4 lesions have been divided into T4a (resectable) and T4b (unresectable), leading to the division of Stage IV into Stage IVA, Stage IVB, and Stage IVC.
62 American Joint Committee on Cancer • 2006 Low-grade tumors rarely metastasize to regional nodes, whereas the risk of regional spread is substantially higher from high-grade cancers. Regional dis- semination tends to be orderly, progressing from intraglandular to adjacent (periparotid, submandibular) nodes, then to upper and midjugular nodes, and occasionally to retropharyngeal nodes. Bilateral lymphatic spread is rare.
For pN, a selective neck dissection will ordinarily include 6 or more lymph nodes, and a radical or modified radical neck dissection will ordinarily include 10 or more lymph nodes. Negative pathologic examination of a lesser number of lymph nodes still mandates a pN0 designation.
Metastatic Sites. Distant spread is most frequently to the lungs.
DEFINITIONS Primary Tumor (T)
TX Primary tumor cannot be assessed T0 No evidence of primary tumor
T1 Tumor 2 cm or less in greatest dimension without extraparenchymal extension(1)(Figure 7.1)
T2 Tumor more than 2 cm but not more than 4 cm in greatest dimension without extraparenchymal extension(1)(Figure 7.2)
T3 Tumor more than 4 cm and/or tumor having extraparenchymal exten- sion(1)(Figures 7.3A, B)
T4a Tumor invades skin, mandible, ear canal, and/or facial nerve (Figures 7.4A–D)
£2 cm Hypoglossal
nerve Lingual nerve
Myelohyoid muscle
T1
FIGURE 7.1. T1 is defined as a tumor 2 cm or less in greatest dimension without extraparenchymal extension (a coronal section thru the floor of the mouth with tumor of the submandibular gland is shown).
7
2-4 cm
Facial nerve
Masseter muscle Isthmus of parotid gland
Facial nerve Mastoid process T2 FIGURE 7.2. T2 is defined as
a tumor greater than 2 cm but not more than 4 cm in greatest dimension without extraparenchymal extension (an axial section with tumor of the deep lobe of the parotid gland is shown).
>4 cm T3
A
FIGURE 7.3. A. T3 is defined as greater than 4 cm and/or tumor having
extraparenchymal extension (a tumor of the superficial lobe of the parotid gland is shown). B. Cross-sectional diagram of T3 tumor with extraparenchymal extension
T3
Masseter muscle Medial pterygoid
muscle
Tumor Parotid gland
B
64 American Joint Committee on Cancer • 2006 T4a
Facial nerve
A T4a
Masseter muscle Medial pterygoid
muscle Mandible
Skin
Parotid gland
B T4a
Masseter muscle Medial
pterygoid muscle
Mandible
Skin
C
FIGURE 7.4. A. T4a is defined as tumor invading skin, mandible, ear canal, and/or facial nerve (as illustrated here). B. Cross-sectional diagram of T4a tumor invading skin. C. Cross-sectional diagram of T4a tumor invading mandible. D. Coronal section of T4 tumor invading ear canal.
T4a
Ear canal
D
7
FIGURE 7.5. A. T4b is defined as tumor invading skull base and/or pterygoid plates and/or encasing carotid artery. In this cross-sectional diagram, the tumor encases the carotid artery. B. Coronal section of T4b tumor invading skull base.
T4b Tumor invades skull base and/or pterygoid plates and/or encases carotid artery (Figures 7.5A, B)
Regional Lymph Nodes (N) (see Figure 2.4) NX Regional lymph nodes cannot be assessed N0 No regional lymph node metastasis
N1 Metastasis in a single ipsilateral lymph node, 3 cm or less in greatest dimension
N2 Metastasis in a single ipsilateral lymph node, more than 3 cm but not more than 6 cm in greatest dimension, or in multiple ipsilateral lymph nodes, none more than 6 cm in greatest dimension, or in bilateral or contralat- eral lymph nodes, none more than 6 cm in greatest dimension
N2a Metastasis in a single ipsilateral lymph node, more than 3 cm but not more than 6 cm in greatest dimension
N2b Metastasis in multiple ipsilateral lymph nodes, none more than 6 cm in greatest dimension
N2c Metastasis in bilateral or contralateral lymph nodes, none more than 6 cm in greatest dimension
N3 Metastasis in a lymph node, more than 6 cm in greatest dimension
Distant Metastasis (M)
MX Distant metastasis cannot be assessed M0 No distant metastasis
M1 Distant metastasis T4b
Carotid artery
A
T4b
Skull base
B
66 American Joint Committee on Cancer • 2006 STAGE GROUPING
I T1 N0 M0
II T2 N0 M0
III T3 N0 M0
T1 N1 M0
T2 N1 M0
T3 N1 M0
IVA T4a N0 M0
T4a N1 M0
T1 N2 M0
T2 N2 M0
T3 N2 M0
T4a N2 M0
IVB T4b Any N M0
Any T N3 M0
IVC Any T Any N M1
NOTE
1. Extraparenchymal extension is clinical or macroscopic evidence of invasion of soft tissues. Microscopic evidence alone does not constitute extraparenchymal exten- sion for classification purposes.
