As part of your NET diagnosis, your doctors will have performed several tests to evaluate the characteristics of your tumour and learn how advanced it is. The “stage“ of a tumour describes the extent of cancer throughout the body. It often includes information such as the size of the tumour and whether it has metastasized (spread).

The “grade“ of a tumour is an assessment of the cancer cells that make up the tumour. By examining these cells under a microscope, a pathologist can determine how quickly the cells are growing and dividing, which can provide information on how likely the cancer is to spread.

Different staging and grading systems are used for different types of cancer. In the case of NETs, the classifications are based on where in the body the tumour is located, with many other factors taken into account. Owing to the complexity of NETs, the staging and grading systems are frequently re-evaluated by the best international experts in the field.


What does it mean if a tumour is “well-differentiated” or “poorly differentiated”?

When examined under a microscope, “well-differentiated” tumours have cells (and cell organization) that look closer to normal tissue. These tumours tend to grow and spread at a slower rate. On the other hand, “poorly differentiated” or “undifferentiated” tumours have abnormal-looking cells with abnormal tissue structures. Generally, undifferentiated tumours are associated with more aggressive behaviour. The pathologist uses this information on differentiation to assign a particular numerical grade to a tumour.


In a study of over 35,000 patients with NETs, it was shown that there is great variation in the expected time of survival following diagnosis. The main factors influencing expected outcome appear to be the type of tumour, its location in the body, and the stage and grade of the tumour. Other factors that play a role include age at diagnosis and sex. In this analysis, women had longer

Today, new surgical approaches, therapies and medications have significantly improved the course of disease for many patients, and new treatments are always on the horizon. Although there are no guarantees, your doctor may be able to give you some helpful information based on your test results. Remember – only your healthcare team can advise you on your particular tumour status and expected outcome.