Major Salivary Glands (Parotid, Submandibular, and Sublingual)
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American Joint Committee on Cancer • 2006 61 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.
description
This staging system is based on an extensive retrospective review of the worldliterature regarding malignant tumors of the major salivary glands. Numerousfactors affect patient survival, including the histologic diagnosis, cellular differentiationof the tumor (grade), site, size, degree of fixation or local extension,facial nerve involvement, and the status of regional lymph nodes as well asdistant metastases. The classification involves the four dominant clinical variables:tumor size, local extension of the tumor, nodal metastasis, and distantmetastasis. The T4 category has been divided into T4a and T4b. T4a indicatesadvanced lesions that are resectable with grossly clear margins; T4b reflectsextension to areas that preclude resection with clear margins. Histologic grade,patient age, and tumor site are important additional factors that should berecorded for future analysis and potential inclusion in the staging system.
Transcript of Major Salivary Glands (Parotid, Submandibular, and Sublingual)
American Joint Committee on Cancer • 2006 61
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Major Salivary Glands (Parotid, Submandibular,and Sublingual)
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INTRODUCTION
This staging system is based on an extensive retrospective review of the worldliterature regarding malignant tumors of the major salivary glands. Numerousfactors 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 asdistant metastases. The classification involves the four dominant clinical vari-ables: tumor size, local extension of the tumor, nodal metastasis, and distantmetastasis. The T4 category has been divided into T4a and T4b. T4a indicatesadvanced lesions that are resectable with grossly clear margins; T4b reflectsextension to areas that preclude resection with clear margins. Histologic grade,patient age, and tumor site are important additional factors that should berecorded 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) arestaged according to the anatomic site of origin (e.g., oral cavity, sinuses, etc.).
Primary tumors of the parotid constitute the largest proportion of salivarygland 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 glandcancer is less common than from head and neck mucosal squamous cancers andvaries according to the histology and size of the primary tumor. Most nodalmetastases 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 extraparenchymalextension, 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.
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Low-grade tumors rarely metastasize to regional nodes, whereas the risk ofregional 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, andoccasionally to retropharyngeal nodes. Bilateral lymphatic spread is rare.
For pN, a selective neck dissection will ordinarily include 6 or more lymphnodes, and a radical or modified radical neck dissection will ordinarily include10 or more lymph nodes. Negative pathologic examination of a lesser numberof 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 assessedT0 No evidence of primary tumorT1 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
Hypoglossalnerve
Lingual nerve
Myelohyoidmuscle
T1
FIGURE 7.1. T1 is defined as a tumor 2 cm or less in greatest dimension withoutextraparenchymal extension (a coronal section thru the floor of the mouth withtumor of the submandibular gland is shown).
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2-4 cm
Facialnerve
Massetermuscle
Isthmus ofparotid gland
Facial nerve
Mastoidprocess
T2FIGURE 7.2. T2 is defined as a tumor greater than 2 cm but not more than 4 cm ingreatest dimension withoutextraparenchymal extension(an axial section with tumor ofthe deep lobe of the parotidgland is shown).
>4 cm
T3
A
FIGURE 7.3. A. T3 is defined as greater than 4 cm and/or tumor havingextraparenchymal extension (a tumor of the superficial lobe of the parotid gland isshown). B. Cross-sectional diagram of T3 tumor with extraparenchymal extensionfrom the parotid gland.
T3
Masseter muscle
Medial pterygoidmuscle
Tumor
Parotid gland
B
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T4a
Facial nerve
A
T4a
Masseter muscleMedial pterygoidmuscle
Mandible
Skin
Parotid gland
B
T4a
Masseter muscleMedialpterygoidmuscle
Mandible
Skin
C
FIGURE 7.4. A. T4a is defined as tumor invading skin, mandible, ear canal, and/orfacial nerve (as illustrated here). B. Cross-sectional diagram of T4a tumor invadingskin. C. Cross-sectional diagram of T4a tumor invading mandible. D. Coronalsection of T4 tumor invading ear canal.
T4a
Ear canal
D
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FIGURE 7.5. A. T4b is defined as tumor invading skull base and/or pterygoidplates and/or encasing carotid artery. In this cross-sectional diagram, the tumor encases the carotid artery. B. Coronal section of T4b tumor invading skullbase.
T4b Tumor invades skull base and/or pterygoid plates and/or encases carotidartery (Figures 7.5A, B)
Regional Lymph Nodes (N) (see Figure 2.4)NX Regional lymph nodes cannot be assessedN0 No regional lymph node metastasisN1 Metastasis in a single ipsilateral lymph node, 3 cm or less in greatest
dimensionN2 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 morethan 6 cm in greatest dimension
N2b Metastasis in multiple ipsilateral lymph nodes, none more than 6 cm ingreatest dimension
N2c Metastasis in bilateral or contralateral lymph nodes, none more than 6 cmin greatest dimension
N3 Metastasis in a lymph node, more than 6 cm in greatest dimension
Distant Metastasis (M)MX Distant metastasis cannot be assessedM0 No distant metastasisM1 Distant metastasis
T4b
Carotid
artery
A
T4b
Skullbase
B
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STAGE GROUPING
I T1 N0 M0II T2 N0 M0III T3 N0 M0
T1 N1 M0T2 N1 M0T3 N1 M0
IVA T4a N0 M0T4a N1 M0T1 N2 M0T2 N2 M0T3 N2 M0T4a N2 M0
IVB T4b Any N M0Any T N3 M0
IVC Any T Any N M1
NOTE
1. Extraparenchymal extension is clinical or macroscopic evidence of invasion of softtissues. Microscopic evidence alone does not constitute extraparenchymal exten-sion for classification purposes.
