People with salivary gland cancer may have questions about their prognosis and survival. Prognosis and survival depend on many factors. Only a doctor familiar with a person’s medical history, type of cancer, stage, characteristics of the cancer, treatments chosen and response to treatment can put all of this information together with survival statistics to arrive at a prognosis.
A prognosis is the doctor’s best estimate of how cancer will affect a person and how it will respond to treatment. A prognostic factor is an aspect of the cancer or a characteristic of the person that the doctor will consider when making a prognosis. A predictive factor influences how a cancer will respond to a certain treatment. Prognostic and predictive factors are often discussed together, and they both play a part in deciding on a treatment plan and a prognosis.
The following are prognostic factors for salivary gland cancer.
The stage, especially the tumour (T) category, is the most important prognostic factor for salivary gland cancer. Large tumours and tumours that have grown into tissue around the salivary glands have a less favourable prognosis.
High-grade tumours have a less favourable prognosis than low-grade tumours. This is because high-grade tumours are usually aggressive, which means they tend to grow and spread quickly. They also have a higher risk of coming back, or recurring, in distant organs such as the lungs or bone.
Adenoid cystic carcinoma has the least favourable prognosis of all types of salivary gland cancer. It tends to grow into and along the nerves of the face (called perineural invasion, or PNI). It also tends to come back, or recur, even many years after first treatment and is not curable.
The following factors may play a small part in helping doctors predict prognosis.
Radiation therapy after surgery may lower the risk that salivary gland cancer will come back, or recur, in the same place.
Perineural invasion (PNI) means that the tumour has grown into the nerves and along the nerves to other areas. Tumours with PNI, especially tumours that affect the cranial nerves, have a less favourable prognosis.
Gender and age may affect prognosis. Men have a poorer prognosis than women. Older people have a less favourable prognosis than younger people.