The patient’s health history and a physical exam are the first diagnostic tools that can determine risk factors and signs of salivary gland cancer. This is followed up by a series of diagnostic techniques, including:
- Proactive removal of the tumour will be done in many cases because most tumours of the parotid are benign, and the physician might not see the benefit in conducting additional diagnostic techniques when the gland will be removed regardless. The tumour is then sent to pathology for microscopic examination to determine if it is cancer or not.
- CT scan is an easy and accessible diagnostic technique that can prepare the specialist for surgery. It can determine the size of the tumour and whether it has spread to the surrounding tissues and organs.
- MRI (Magnetic Resonance Imaging) can distinguish structures between different tissues and help to establish if there is spread or metastasis to the surrounding area.
- PET-CT (Position Emission Tomography) is a whole body scan that can determine metastasis and where the primary tumour is located. (Head and neck cancer guide)
- Biopsy of the salivary glands can be performed. This is a Fine needle Aspirate (FNA) which extracts cells from the lump or tumour for cytological diagnosis, or a core biopsy that extracts a small sample of the tumour for histological diagnosis. The advantages of the FNA are that it is very fast, and results can be readily obtained while a core biopsy might take more time; however, it is a more sensitive diagnostic tool. (Canadian Cancer Society)
Staging refers to a cancer classification system that tells the physician how far along the disease is. The TNM system of the American Joint Committee on Cancer is widely accepted and used across the world. T stands for size of the tumour; N refers to the spread to the lymph nodes; and M means metastasis or spread to distant organs.
T : Size of the tumour
|T0: No evidence of primary tumour.|
|Tis: Carcinoma in situ: the cancer has affected the epithelial cells (specialized cells that produce saliva) lining the oral cavity, but the tumour is not deep.|
|T1: Tumour is 2 cm (1 cm equals 0.39 inches) or smaller.|
|T2: Tumour is larger than 2 cm but smaller than 4 cm.|
|T3: Tumour is larger than 4 cm.|
|T4: The tumour is any size and has invaded adjacent structures, such as the larynx, bone, connective tissues, or muscles.|
N: Lymph node involvement
|N0: No metastasis in the regional lymph nodes.|
|N1: Metastasis in one lymph node on the same side of the primary tumour and smaller than 3 cm.|
|N2: Divided into 3 subgroups. N2a is metastasis in one lymph node larger than 3 cm and smaller than 6 cm. N2b is metastasis in multiple lymph nodes on the same side of the tumour, none larger than 6cm. N2c denotes one or more lymph nodes, which may or may not be on the side of the primary tumour, none larger than 6 cm.|
|N3: Metastasis in lymph node larger than 6 cm|
M : Distant metastasis
|M0: No distant metastasis.|
|M1: Distant metastasis present.|
Santhanam, Kausalya, and Rebecca J. Frey. “Oral Cancers.” The Gale Encyclopedia of Cancer: A Guide to Cancer and Its Treatments, edited by Kristin Fust, 4th ed., vol. 2, Gale, 2015, pp. 1295-1303. Gale Virtual Reference Library.