Salivary glands are the organs responsible for producing saliva. As expected, all the salivary glands are located within the head and neck region. There are 3 pairs of major salivary glands, namely the parotid glands (situated just in front of the ears), the submandibular glands (situated below the jaw bone, one on each side) and the sublingual glands (situated within the front of the mouth below the tongue). In addition, there are thousands of minor salivary glands scattered throughout the mucosal lining of the mouth, nose and throat.

Salivary gland surgery is surgery to remove part or all of a diseased salivary gland.

The commonest indication for surgery is a tumour arising from the gland in question. This tumour may be benign (non-cancerous) or malignant (cancerous).

Other less common salivary gland diseases requiring surgery include stone formation, chronic inflammation of the gland or certain bad infections.

Tumours are abnormal growths made up of cells which no longer obey the body’s controlling mechanisms. Tumours may be benign (non-cancerous) or malignant (cancerous).

Like any other organ in the human body, tumours can arise within the salivary glands. They usually present as a persistent swelling or lump. Depending on the gland involved, the likelihood of the tumour being cancerous varies.

Salivary gland stones are calcium deposits which form within the ducts (saliva channels) of the major salivary glands. They range in size from little more than a grain of sand to large stones several centimetres in diameter. Tiny stones may not give rise to any symptoms. However, once a stone becomes large enough to block a saliva channel, then problems arise. The main symptoms are pain and swelling of the gland brought on by eating.

The vast majority of stones arise within the submandibular salivary glands. Parotid gland stones are much less common and sublingual gland stones are very rare.

Parotid surgery is surgery to remove part or all of the parotid gland. The commonest indication for parotid surgery is to remove a tumour arising within the gland.

The facial nerve is the nerve that moves the muscles of the face. Damage to this nerve or one of its branches will result in paralysis to part or all of the face. The facial nerve and its branches run right through the parotid gland, dividing the gland into a large part superficial to the nerve (superficial lobe), and a small part deep to the nerve (deep lobe).

Parotid surgery is therefore intimately related to the facial nerve. During parotid surgery, the facial nerve and its branches need to be identified, traced and preserved. Accidental damage to the nerve may lead to permanent facial paralysis.

In addition to the standard risks associated with all forms of surgery (eg. bleeding, infection etc), the main risk associated with parotid surgery is accidental damage to the facial nerve.

While facial nerve damage can be a very debilitating injury, in trained, experienced hands, the risk of damage to the facial nerve should be less than 1%.

In general, there are 3 types of parotid surgery.

a. A superficial parotidectomy involves removal of only the part of the parotid superficial to the facial nerve. This is the commonest parotid operation because most benign tumours of the parotid occur in the superficial lobe.

b. A total parotidectomy involves removal of both the superficial and deep parts of the gland. The facial nerve and all its branches are preserved. This operation is usually performed for benign tumours which arise within, or extend to involve the deep lobe of the gland.

c. A total parotidectomy + neck dissection involves removal of the entire parotid gland together with the surrounding lymph nodes in the neck. This operation is performed for parotid cancers where there is probable spread of cancer (metastases) to the lymph nodes.

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.

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.

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.

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.

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.