by Jason Wasserman MD PhD FRCPC
October 3, 2022
Squamous cell carcinoma (SCC) is a type of oropharyngeal cancer. The oropharynx is an area of the throat that includes the tonsils, base of the tongue, uvula, and soft palate. Most tumours are caused by a virus called human papillomavirus (HPV). This type of cancer quickly spreads to lymph nodes especially those in the neck. For many patients, the first sign of the disease is a noticeable lump in the neck.
The diagnosis of squamous cell carcinoma is usually made after a small tissue sample is removed in a procedure called a biopsy. The biopsy may be taken from the oropharynx or it may be taken from the neck. The diagnosis can also be made after the entire tumour is removed although this is much less common. For some patients, surgery may be performed to remove the entire tumour. Other patients may receive radiation therapy with or without surgery to remove the tumour. If the tumour is removed, it will be sent to a pathologist who will prepare another pathology report. This report will confirm or revise the original diagnosis and provide additional important information such as tumour size and spread of tumour cells to lymph nodes. This information is used to determine the cancer stage and to decide if additional treatment is required.
Squamous cells infected with HPV produce a large amount of a protein called p16 which pathologists can see using a test called immunohistochemistry. Tumours made up of cells that produce extra p16 are described as positive or reactive while those that do not produce extra p16 are reported as negative or non-reactive. Most tumours in the oropharynx will be positive for p16.
This is the size of the tumour. The tumour is usually measured in three dimensions but only the largest dimension is described in your report. For example, if the tumour measures 4.0 cm by 2.0 cm by 1.5 cm, your report will describe the tumour as being 4.0 cm. The tumour size is used to determine the tumour stage (see Pathologic stage below) and larger tumours are associated with a worse prognosis.
A margin is any tissue that was cut by the surgeon in order to remove the tumour from your body. The types of margins described in your report will depend on the organ involved and the type of surgery performed. Margins will only be described in your report after the entire tumour has been removed. A negative margin means that no tumour cells were seen at any of the cut edges of tissue. A margin is called positive when there are tumour cells at the very edge of the cut tissue. A positive margin is associated with a higher risk that the tumour will recur in the same site after treatment.