Grades of lung NETs

The grade of a lung neuroendocrine tumour (NET) gives doctors an idea of how the tumour might behave. There are 3 grades of lung NETs.

What is the grade of a tumour

Grading is a way of dividing tumour cells into groups based on how the cells look under the microscope. This gives your doctor an idea of how quickly or slowly the tumour might grow and whether it’s likely to spread.

Grade 1

The cells look very like normal cells. They are also called low grade or well differentiated. Differentiation means how developed or mature a cell is. Cancer cells are not as mature as normal cells.

Grade 1 tumours are usually slow growing and less likely to spread.

Typical carcinoid (TC) is a low grade or well differentiated lung NET.

Grade 2

The cells look more abnormal. They behave somewhere between low grade and high grade tumours. This grade is also called moderately differentiated or intermediate grade.

Atypical carcinoid (AC) is an intermediate grade or moderately differentiated.

Grade 3

The cells look very abnormal. They tend to grow quickly and are more likely to spread. Grade 3 is also called poorly differentiated or high grade.

Large cell neuroendocrine cancer (LCNEC) and small cell lung cancer (SCLC) are high grade or poorly differentiated lung NETs.

Treatment

Knowing the grade helps your doctor decide which treatment you need. Treatment also depends on:

  • the type of cell the NET started in
  • where the NET is
  • other health conditions you may have
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Last reviewed: 
29 Mar 2021
Next review due: 
29 Mar 2024

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