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Lung neuroendocrine tumours and carcinomas

Lung neuroendocrine tumours or carcinomas are rare, slow-growing tumours that develop in diffuse neuroendocrine cells in the lungs and airways (the path that air follows to reach the lungs, including the larynx, trachea and bronchi).

Over one-quarter (28%) of neuroendocrine tumours and carcinomas are found in the lungs. They account for about 2%–3% of lung cancers.

Most people with lung neuroendocrine tumours do not have any identifiable risk factors. Tobacco smoking causes the vast majority of small cell lung cancers (SCLC) and large cell neuroendocrine carcinomas (LCNEC), the most aggressive types of lung neuroendocrine cancer. Rarely, neuroendocrine cancers may develop from inherited or genetic conditions, such as multiple endocrine neoplasia (MEN) syndromes.

Recognizing symptoms and getting regular checkups are the best ways to detect lung neuroendocrine tumours and carcinomas early. The sooner symptoms are reported, the sooner a doctor can diagnose and treat the cancer.

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Signs and symptoms

Lung neuroendocrine tumours and carcinomas cause a variety of signs and symptoms. The majority of tumours are slow-growing and symptoms result from the growth of the tumour (its size and location). Symptoms may also be the result of specific hormones the tumour produces. Many neuroendocrine tumours or carcinomas are small and non-functional (do not produce hormones), causing no symptoms at all.

Other health conditions can have the same signs and symptoms as lung neuroendocrine cancer, so having any of the following symptoms does not necessarily mean a person has cancer. However, it is important to see a doctor about the following.

Symptoms caused by tumour growth

  • difficulty breathing
  • wheezing
  • cough
  • coughing up blood
  • chest infections
  • weight loss
  • Usually, central lung tumours (which develop near the centre of the lung) cause symptoms. Peripheral lung tumours (which develop near the edges of the lung) often do not cause symptoms and are usually discovered on a chest x-ray.

Symptoms caused by hormone production

  • flushing
  • diarrhea
  • wheezing
  • palpitations

Occasionally, lung neuroendocrine tumours and carcinomas can cause carcinoid syndrome. This occurs when the tumour produces and releases abnormal amounts of serotonin hormone into the bloodstream.

Cushing’s syndrome is another group of symptoms, including weight gain, weakness and high blood pressure. It may result if the lung neuroendocrine tumour produces too much of the hormone cortisol.

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In recent years, the reported incidence of neuroendocrine tumours has increased. This increase may be due to more awareness of the disease and better diagnostic tests.

Find out more about tests used to diagnose and stage neuroendocrine cancer. More information on diagnosis of small cell lung cancer and large cell neuroendocrine carcinoma is discussed in lung cancer.

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Pathology and staging

Lung neuroendocrine tumours and carcinomas are divided into the following types:

  • typical carcinoid tumours
  • atypical carcinoid tumours
  • small cell lung cancer (SCLC)
  • large cell neuroendocrine carcinoma (LCNEC)

Typical carcinoid tumours

These tumours account for 80%–90% of all carcinoid lung tumours. They can develop near the centre of the lung (known as central carcinoids) or toward the edges of the lung (known as peripheral carcinoids).

Typical carcinoid tumours are well-differentiated endocrine tumours that are benign or potentially malignant. They grow slowly but sometimes (in about 5% of cases) metastasize to the lymph nodes in the lung. They rarely spread to other lymph nodes or outside the chest.

Atypical carcinoid tumours

These tumours are much less common than typical carcinoid tumours. They have a higher mitotic count (number of dividing cells) and features similar to well-differentiated neuroendocrine carcinomas. These tumours grow faster and are more likely to spread to other organs than typical carcinoid tumours. Atypical carcinoid tumours can have symptoms similar to those of typical carcinoid tumours, depending on the tumour’s location and if it produces hormones.

Small cell lung cancer (SCLC)

SCLC is also known as oat cell carcinoma and small cell carcinoma. It accounts for 15%–20% of all lung cancers. It has a strong association with tobacco smoking. Small cell lung cancer is the most aggressive of all lung cancers, and it usually progresses rapidly. SCLC shows neuroendocrine features, such as producing hormones that can cause signs and symptoms of disease outside the chest (called paraneoplastic syndromeparaneoplastic syndromeA group of symptoms that occurs when substances released by cancer cells disrupt the normal function of nearby or distant organs or tissues.).

Large cell neuroendocrine carcinoma (LCNEC)

LCNEC is a variant of large cell lung cancer, which is a type of non–small cell lung cancer. It is an aggressive type of neuroendocrine lung cancer. The staging is similar to that of non–small cell lung cancer.

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Each person with lung neuroendocrine tumours or carcinomas will have a treatment plan designed for them by their healthcare team. The team will recommend treatment options based on the specific characteristics of the cancer and the unique needs of the person.

Treatments vary by the type of lung neuroendocrine tumours or carcinomas:

It is important to have regular follow-up visits after treatment to watch for any recurrence or actively monitor and manage any remaining neuroendocrine cancer that could not be fully removed by surgery.

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