Neuroendocrine carcinoma (NEC)

Neuroendocrine carcinomas (NECs) are cancers that start in the neuroendocrine system .  They can develop in different parts of the body, such as the stomach, bowel, pancreas or lungs.

Neuroendocrine carcinomas are part of a group of cancers called neuroendocrine cancer. You might hear the term neuroendocrine neoplasms (NEN). This means the same thing as neuroendocrine cancer.

 There are 2 key groups of neuroendocrine cancer: 

• neuroendocrine tumours (NETs )
• neuroendocrine carcinomas (NECs )

The cells of NECs look very abnormal. They are not like normal neuroendocrine cells at all. Doctors call them poorly differentiated cancers. They are also fast growing and are likely to spread. Unfortunately this means NECs can be difficult to treat.

This page is about neuroendocrine carcinoma (NEC).

What is the difference between neuroendocrine carcinomas (NECs) and neuroendocrine tumours (NETs)?

A specialist doctor (pathologist ) looks at the cancer cells under a microscope. This is to find out what type of cancer you have. They check to see whether the cells look normal or not. If they are abnormal, the pathologist reports:

• how abnormal they look – this is called differentiation
• how quickly or slowly the cancer cells are dividing and growing – this is called grading

Neuroendocrine Tumours (NETs)

• NETs are well differentiated cancers. This means they look abnormal. But they still have some similarities to normal neuroendocrine cells.
• NETs may be grade 1, 2 or 3. This means they can be slow, medium or fast growing.

Neuroendocrine Carcinomas (NECs)

• NECs are poorly differentiated cancers. This means they look very abnormal and are not like normal neuroendocrine cells at all.
• Doctors don’t usually give NECs a grade. This is because they are all fast growing.
• There are different types of NEC, depending on what the cells look like. The main types are small cell NEC and large cell NEC.

There are some other differences between NETs and NECs.

The difference between high grade NETs and NECs

Some NETs are high grade. This means they are fast growing. But high grade NETs can also be well differentiated. This means that they look abnormal. But there are still some similarities to normal neuroendocrine cells.

This is different to NEC. All NEC look highly abnormal (poorly differentiated), as well as being high grade.

Can NECs disrupt hormones and cause symptoms?

Neuroendocrine cancer can disrupt how much hormone the neuroendocrine cells make and release. It is much more common for NETs to produce abnormal levels of hormone than NECs. Doctors sometimes group NETs depending on whether they make abnormal levels of hormone:

• Non-functioning NETs make and release normal levels of hormone.
• Functioning NETs make and release abnormal levels of hormone. 

NECs are rarely functional. They almost never have symptoms linked to making an abnormal amount of hormones.

How common are neuroendocrine carcinomas (NECs)?

NECs are not common. Around 1,500 are people are diagnosed with an NEC in England every year.

They are less common than NETs. Around 60 out of 100 neuroendocrine cancers (around 60%) are NETs. And around 40 out of 100 neuroendocrine cancers (around 40%) are NECs.

Types of neuroendocrine carcinoma (NEC)

Doctors group NECs depending on where they start to develop. This is called the primary site . For example, a lung NEC starts to develop in the lung.

They also group NEC depending on what the cancer cells look like. There are different types including:

• small cell NEC
• large cell NEC

You can also get neuroendocrine cancer cells mixed in a tumour with a different type of cancer. Doctors call this MiNEN or mixed cell carcinoma.

Tests to diagnose neuroendocrine carcinoma (NEC)

If your doctor suspects cancer, you have tests to check the type of cancer you have. Tests also show the size of the cancer and whether it has spread. This helps your doctor plan your treatment.

Tests for NEC might include:

• blood tests - these check your general health 
• tests to look inside your body and take a cancer sample (biopsy ) - such as endoscopy , colonoscopy or bronchoscopy
• an ultrasound on its own, or as part of the test above
• CT scan of your chest and tummy
• MRI scan
• PET-CT scan to show the size of the cancer and whether it has spread 

Treatment for neuroendocrine carcinoma (NEC)

Your treatment depends on your:

• primary site - this is where the NEC starts to grow
• type - this is either small cell, large cell or mixed cell
• stage - this means the size of the cancer and whether it has spread
• general health and wellbeing

We have information about the different types of treatment in our treatment section.

Treating lung NEC

Your treatment depends on the stage of your cancer, and whether it is large cell or small cell.

Large cell lung NEC

Early stage means that the cancer is small and hasn’t spread. Treatment for early stage is usually surgery to remove the part of the lung that contains the cancer. You often have chemotherapy afterwards. You might also have radiotherapy .

You have chemotherapy if your cancer is more advanced. You usually have a combination of chemotherapy drugs. For example, etoposide and either cisplatin or carboplatin.

This is similar to the treatment for small cell lung cancer (SCLC). 

Small cell lung carcinoma (SCLC)

Small cell lung cancers tend to grow quickly and spread quite early on. So the main treatment is chemotherapy.  You might have chemotherapy:

• on its own, or together with immunotherapy
• before, after or with radiotherapy
• before or after surgery – this is only for very early small cell lung cancer

There are different chemotherapy drugs. You might have etoposide with either cisplatin or carboplatin.

You may have these drugs together with the immunotherapy drugs atezolizumab or durvalumab.

Treating digestive neuroendocrine carcinoma (NEC)

Digestive NECs start in the digestive system and include:

• small bowel NECs
• large bowel and rectal NECs
• stomach NECs
• pancreas NECs

You might have surgery if your cancer hasn’t spread. The type of surgery you have depends on where the cancer is in your body. You can read about the different surgeries in the treatment section for your type of neuroendocrine cancer.

You usually also have chemotherapy treatment as well as surgery. You might have this:

• before surgery – this is called neoadjuvant chemotherapy
• after surgery – this is called adjuvant chemotherapy

You have chemotherapy on its own or with radiotherapy. This is called chemoradiotherapy.

Chemotherapy drugs include:

• carboplatin or cisplatin
• etoposide
• irinotecan

Treating mixed cell carcinoma (MiNEN)

Some cancer cells contain neuroendocrine cancer cells mixed with a different type of cancer. Doctors call this MiNEN or mixed cell carcinoma.

Treatment is similar to other types of NEC.

For MiNEN that hasn't spread, you might have surgery, followed by chemotherapy. The chemotherapy drugs you have depend on your situation. Chemotherapy options might include:

• cisplatin or carboplatin with etoposide
• 5FU with oxaliplatin or irinotecan

Survival (prognosis) for neuroendocrine carcinoma (NEC)

Unfortunately NEC can be harder to treat than NETs. This is because they are fast growing and have often spread to other parts of the body.  

Your prognosis is better if you have an early stage NEC that has not spread. In a few cases, it might be possible for the surgeon to completely remove your cancer. But there is often a high chance that the cancer will come back.

Prognosis is also affected by:

• where the NEC started in your body
• whether you have a large or small cell carcinoma
• your general health and fitness

Coping with neuroendocrine cancer

You might have physical changes to your body because of your cancer or the treatment. These changes can be hard to cope with and can affect the way you feel about yourself. It can help to talk to friends and family. Or join a support group to meet people in a similar situation.

We have a discussion forum called Cancer Chat. It is a place for anyone affected by cancer. You can share experiences, stories and information with other people with cancer.

You might need practical advice about benefits or financial help. There is help and support available. There are also organisations to support and provide information to people affected by neuroendocrine cancer.