Parotid Cancer

1. What is Parotid Cancer?

Parotid cancer is any cancer (malignancy) that begins in the parotid gland itself.

It excludes cancers which begin elsewhere but later extend into or spread to the parotid gland.

Parotid cancer is not just a single type of cancer, but rather a group of cancers.
There are many different types of tumours which can arise within the parotid gland.
Most (80%) of these parotid tumours are benign, but a significant portion (20%) are malignant. There are 18 varieties of parotid cancers recognised.

2. What is the difference between a benign and malignant tumour of the parotid gland?

Benign tumours do not spread. They continue to grow bigger at their place of origin, and may squeeze or compress neighbouring organs, but they do not invade neighbouring tissues and they do not spread to other regions of the body.

Malignant tumours (parotid cancers) however, not only grow within the gland, but they invade surrounding tissues, spread via the body’s water channels to the lymph nodes of the neck, and eventually through the bloodstream to the rest of the body.
Untreated, parotid cancers are fatal.

 

3. Do all parotid tumours need to be removed?

In general, all parotid tumours should be removed.

For malignant tumours, surgical removal is the mainstay of treatment. If the cancer is left untreated, the outcome would be death.

For benign tumours, surgical removal is still recommended for the following reasons:
a. It is frequently difficult to decide if a tumour is benign or malignant without removing and examining the entire tumour first. Even if the pre-operative investigations do not show obvious features of malignancy, there will be residual uncertainty in many cases.
b. Even if the tumour is benign, it will continue to enlarge over time. Unless the patient is very old or infirm, it is always better to remove the tumour early when it is small.
c. Some benign tumours can become malignant with time. It is therefore not advisable to leave even benign tumours for too long.

 

4. What is the treatment for benign parotid tumours?

There is only one treatment for benign parotid tumours which is surgical removal.
The good news is that once the tumour has been completely removed, no additional treatment is required.

 

5. What is the treatment for parotid cancer?

In general, the treatment for parotid cancer involves 2 steps: Surgery first, followed by radiotherapy 6-8 weeks later.
Also, the extent of surgery is more extensive than that used to treat benign tumours.
For benign tumours, all that is required is complete removal of the tumour without spilling any tumour or leaving any tumour behind. In most cases this would involve just a superficial parotidectomy. In some cases where the tumour involves the deep lobe, a total parotidectomy is required.
For malignant tumours, the standard operation would not only be a total parotidectomy, but with a neck dissection at the same sitting to remove the surrounding neck nodes. The reason for removing the surrounding neck nodes is because many cancers may already have microscopic spread to these nodes.
In all cases, every attempt is made to preserve the facial nerve. However, if the cancer invades the facial nerve or any other neighbouring structure eg. muscle or skin, then in the interests of curing cancer, these structures need to be removed with the tumour as well. Complete surgical removal of the cancer, even before radiotherapy is administered, is by far the best chance to achieve a cure.