Prognosis and survival for neuroendocrine tumours (NETs)

If you have a neuroendocrine tumour (NET), you may have questions about your prognosis. A prognosis is the doctor’s best estimate of how cancer will affect someone and how it will respond to treatment. Prognosis and survival depend on many factors. Only a doctor familiar with your medical history, the type, stage and characteristics of the cancer, the treatments chosen and the response to treatment can put all of this information together with survival statistics to arrive at a prognosis.

A prognostic factor is an aspect of the cancer or a characteristic of the person (such as age) 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. They both play a part in deciding on a treatment plan and a prognosis.

The following are prognostic and predictive factors for NETs.

The stage of NETs is an important factor in determining the outcome. Stage includes the size of the tumour and where the cancer is in the body. Tumours that are in early stages when they are found have the most favourable prognosis. Tumours that are in later stages (they have spread into nearby lymph nodes or other organs) have a less favourable prognosis.

How different the tumour cells are from normal cells is described as differentiation. The level of differentiation is an important prognostic factor for NETs. Well-differentiated NETs have a better prognosis than poorly differentiated neuroendocrine carcinomas.

Grade is a description of how fast NET cells are growing. The grade may be determined by counting the cells that are dividing (called mitotic count). But more often a test called Ki-67 labelling index is used. It measures the number of cells with Ki-67 antigen in the nucleus. This is a marker that shows the increase in the number of cells because of cell growth and division. NETs with a low Ki-67 index have a more favourable prognosis and longer survival than those with a high Ki-67 index.

CgA (Chromogranin A) and hormones are substances that can be measured to help diagnose NETs and monitor response to treatment. People with high levels of CgA in the blood or 5-HIAA in the urine have a poorer prognosis compared to people with normal levels.

Even when any symptoms of NETs are controlled, increased hormone levels mean that the cancer continues to grow (progress). For example, elevated 5-HIAA levels in the urine means that there is too much serotonin and this can cause heart problems (called carcinoid heart disease). People with carcinoid heart disease have a less favourable prognosis.

People with Cushing syndrome also tend to have a less favourable prognosis. Cushing syndrome is a group of symptoms caused by too much of the hormone cortisol in the body.