Neuroendocrine tumour of the lung – Diagnostics – Overview of Information and Clinical Research

Lung neuroendocrine tumours (NETs) are a rare form of cancer that can present unique diagnostic challenges, often discovered unexpectedly during routine check-ups or investigations for unrelated symptoms, making early and accurate diagnosis essential for proper care.

Introduction: Who Should Undergo Diagnostics and When to Seek Medical Evaluation

Many people with lung neuroendocrine tumours discover their condition quite by accident. Some individuals don’t have any symptoms at all, and doctors find these tumours when performing tests for something else entirely. However, when symptoms do appear, it’s important to seek medical attention promptly to determine what’s causing them and whether further investigation is needed.^[3]

You should consider talking to your doctor if you experience certain warning signs that don’t go away. These include a persistent cough that continues for weeks without improvement, unexplained wheezing or shortness of breath that makes it hard to catch your breath during normal activities, or coughing up blood. Other concerning symptoms include ongoing chest pain or a feeling of aching in your chest area, repeated chest infections that keep coming back, feeling extremely tired all the time without a clear reason, or losing weight without trying to do so.^[3]

It’s worth noting that these symptoms can be caused by many different conditions, not just lung neuroendocrine tumours. However, they should not be ignored. The earlier any potential problem is identified, the better the chances of managing it effectively. This is especially true because lung NETs, while rare, can sometimes be treated very successfully when caught early.^[1]

Some lung neuroendocrine tumours, which are cancers that start in special cells in the lung that control various body functions, can produce extra hormones that get released into the bloodstream. When this happens, people might experience symptoms that seem unrelated to lung problems, such as sudden skin flushing where the face and upper body turn red, frequent diarrhea, wheezing, or a racing heartbeat. This collection of symptoms is called carcinoid syndrome, and while it’s less common in lung NETs compared to those starting in the digestive system, it can occur, particularly if the tumour has spread to other parts of the body like the liver.^[3]

⚠️ Important

The symptoms of lung neuroendocrine tumours can be very similar to those of other, more common lung conditions or even other types of lung cancer. This means that experiencing these symptoms doesn’t automatically mean you have a NET. However, it does mean you should see a healthcare professional who can properly evaluate your situation and determine what tests, if any, are needed.

Classic Diagnostic Methods for Identifying Lung Neuroendocrine Tumours

Diagnosing lung neuroendocrine tumours typically begins with a thorough examination by a healthcare professional. During a physical exam, your doctor will check for any visible signs of illness, such as swollen lymph nodes, which are small bean-shaped structures that help fight infection, or signs that a tumour might be producing excess hormones. The doctor will also ask detailed questions about your symptoms, when they started, and how they’ve been affecting your daily life.^[11]

If your doctor suspects a lung problem based on your symptoms and physical examination, the next step usually involves imaging tests. These are procedures that create pictures of the inside of your body, allowing doctors to see structures and any abnormalities that wouldn’t be visible from the outside. A chest X-ray is often one of the first tests performed because it’s quick, widely available, and can reveal shadows or unusual areas in the lungs that need further investigation.^[11]

When an X-ray shows something that requires more detailed examination, doctors typically order more sophisticated imaging. A computed tomography scan, commonly called a CT scan, uses X-rays and computer technology to create detailed cross-sectional images of your lungs and chest. This test can show the size and location of any tumours more clearly than a regular X-ray, and it can also reveal whether the cancer has spread to nearby lymph nodes or other structures in the chest.^[11]

Magnetic resonance imaging, or MRI, is another imaging technique that uses powerful magnets and radio waves instead of X-rays to create detailed pictures of soft tissues in the body. While not always used for lung NETs, an MRI can be particularly helpful in certain situations, such as determining whether a tumour has spread to the brain or other organs.^[11]

A specialized type of scan called a positron emission tomography scan, or PET scan, can be especially useful for lung neuroendocrine tumours. This test involves injecting a small amount of radioactive material into a vein, which is absorbed by cells in the body. Cancer cells typically absorb more of this material than normal cells, making them show up more brightly on the scan. For neuroendocrine tumours specifically, doctors often use a type of PET scan called a somatostatin receptor PET scan or dotatate PET scan. This special scan uses a tracer that attaches to receptors that neuroendocrine tumour cells often have, making these particular cancers easier to detect.^[11]

While imaging tests can show suspicious areas, they cannot definitively determine whether those areas are cancer or, if they are cancer, what type it is. For that, doctors need to examine actual tissue under a microscope, which requires a biopsy. A biopsy involves removing a small sample of tissue from the suspicious area so it can be analyzed in a laboratory. How the biopsy is performed depends on where the tumour is located in the lung.^[11]

One common method for obtaining lung tissue is bronchoscopy, a procedure where a thin, flexible tube with a camera on the end is inserted through the nose or mouth, down the windpipe, and into the airways of the lungs. This allows the doctor to see inside the airways and take small tissue samples from any abnormal areas. The procedure is usually done under sedation, so patients don’t experience discomfort during it.^[11]

In some cases, doctors might perform a needle biopsy, where a thin needle is inserted through the skin of the chest wall and into the lung to collect a tissue sample. This is often done with the guidance of CT scanning to ensure the needle reaches the correct location. Once tissue samples are obtained, specialists called pathologists examine them under a microscope to determine whether cancer cells are present and, if so, what type they are.^[11]

Because some neuroendocrine tumours produce excess hormones, doctors may also recommend blood and urine tests to look for signs of these extra hormones. Finding elevated hormone levels can provide additional evidence supporting a diagnosis of a functioning neuroendocrine tumour and can help doctors understand which symptoms might be related to hormone production.^[11]

Another diagnostic procedure that might be used is ultrasound, which uses sound waves to create images of structures inside the body. While not typically the primary tool for diagnosing lung NETs, ultrasound can be helpful in examining other organs, particularly the liver, to see if the cancer has spread there.^[11]

Throughout the diagnostic process, doctors work to not only identify whether a neuroendocrine tumour is present but also to classify it correctly. Lung NETs are grouped into different subtypes with very different characteristics. Typical carcinoid tumours are slow-growing and account for the majority of lung NET cases. They generally have a more favorable outlook when found early. Atypical carcinoid tumours are also slow-growing but behave somewhat more aggressively than typical carcinoids and have a slightly higher chance of spreading to other parts of the body.^[1]

There are also more aggressive types of lung neuroendocrine cancer called neuroendocrine carcinomas, or NECs. Small cell carcinoma is the most aggressive type, tending to grow rapidly and often being diagnosed when it has already reached an advanced stage. Large cell neuroendocrine carcinoma, or LCNEC, is another rare and aggressive type with features of both small cell lung cancer and non-small cell lung cancer.^[1]

⚠️ Important

Lung neuroendocrine tumours and lung neuroendocrine carcinomas are very different diseases that require different treatment approaches. It’s essential that you understand which type you have been diagnosed with, as this will significantly affect your treatment plan and outlook. Don’t hesitate to ask your doctor or specialist nurse to clarify your specific diagnosis if you’re unsure.

Diagnostics for Clinical Trial Qualification

When patients with lung neuroendocrine tumours consider participating in clinical trials, they typically need to undergo specific diagnostic tests to determine whether they meet the eligibility criteria for the study. Clinical trials are research studies that test new treatments or new ways of using existing treatments, and they have strict requirements to ensure the safety of participants and the reliability of the results.^[11]

One of the most fundamental requirements for clinical trial enrollment is having a confirmed diagnosis through biopsy. Trial organizers need to know not just that a patient has a lung neuroendocrine tumour, but specifically which subtype it is. This often means that tissue samples must be reviewed by specialized pathologists who have expertise in classifying neuroendocrine tumours. Sometimes, patients need to provide tissue samples from their original biopsy to the trial site for this review, or occasionally, a new biopsy might be required if the original tissue is not available or not sufficient.^[11]

Clinical trials also typically require comprehensive imaging to establish the exact extent of the disease before treatment begins. This baseline imaging serves as a reference point that doctors will use to measure whether the treatment being tested is working. Common imaging tests required for trial enrollment include CT scans of the chest, abdomen, and pelvis to look for any spread of the cancer. Some trials may also require PET scans, particularly the specialized somatostatin receptor PET scans that are especially useful for visualizing neuroendocrine tumours.^[11]

Blood tests form another important category of diagnostic requirements for clinical trial participation. These tests help ensure that a patient’s organs are functioning well enough to safely receive the treatment being studied. For example, blood tests that measure kidney function and liver function are almost always required because many cancer treatments are processed by these organs. If these organs aren’t working properly, the treatment could build up to dangerous levels in the body or the patient might not be able to tolerate the side effects.^[11]

Complete blood counts, which measure the numbers of different types of blood cells, are also standard requirements. Cancer treatments can affect the bone marrow’s ability to produce blood cells, so doctors need to know that a patient has adequate blood cell counts before starting treatment. Blood tests may also check for specific markers or substances in the blood that indicate how the neuroendocrine tumour is behaving or what characteristics it has.^[11]

Some clinical trials, particularly those testing targeted therapies or immunotherapies, may require additional specialized testing of the tumour tissue. This might include looking for specific genetic mutations or measuring the levels of certain proteins on the tumour cells. For example, a trial testing a drug that targets a specific pathway might only enroll patients whose tumours have alterations in that pathway. This type of testing, often called biomarker testing, helps match patients to treatments that are most likely to benefit them.^[11]

Tests to assess a patient’s overall health and ability to carry out daily activities are also common requirements. Doctors use what’s called a performance status scale to rate how well a person is functioning. This helps determine whether someone is strong enough to participate in a trial and potentially handle the side effects of an experimental treatment. The assessment involves evaluating whether a person can care for themselves, how much time they spend in bed or a chair during the day, and whether they can work or do their usual activities.^[11]

For trials involving treatments that might affect specific organs, additional specialized tests may be required. For instance, if a treatment could potentially affect heart function, an echocardiogram or electrocardiogram might be needed to ensure the heart is healthy before starting the trial. Similarly, lung function tests might be required if there’s concern about how a treatment could affect breathing.^[11]

The specific diagnostic requirements vary considerably from one clinical trial to another, depending on the treatment being tested, the phase of the trial, and the particular questions the researchers are trying to answer. Patients interested in clinical trials should discuss the specific requirements with the trial team to understand what will be needed and whether they can meet those requirements. The process of qualifying for a clinical trial can seem demanding, but these requirements exist to protect patients and ensure that the trial results will be as accurate and useful as possible for advancing medical knowledge.

Prognosis and Survival Rate

Prognosis

The outlook for people diagnosed with lung neuroendocrine tumours varies widely depending on several important factors. The type of lung NET you have is one of the most significant factors affecting your prognosis. The different subtypes of lung NETs behave very differently from each other, with some growing slowly over many years and others growing much more rapidly. The stage at which the tumour is diagnosed also plays a crucial role in determining the outcome. When a tumour is found at an early stage and is still confined to one area of the lung, treatment options are often more effective and the chances of long-term survival are generally better.^[1]

Whether the tumour can be completely removed through surgery is another important consideration in determining prognosis. When surgery is possible and the entire tumour can be taken out, patients often have better outcomes. For typical and atypical carcinoid tumours, surgery is frequently the main treatment and may be all that’s needed if the cancer hasn’t spread. However, for more aggressive types like small cell carcinoma, surgery alone is often not sufficient even when it’s possible, and additional treatments are usually needed.^[8]

The development of medical treatments over recent years has improved outcomes for many patients with lung NETs. Advances in surgery techniques, chemotherapy drugs, radiation therapy methods, and newer targeted therapies have all contributed to better results. Additionally, some lung NETs remain stable for long periods without growing, and in these cases, doctors might simply monitor the tumour with regular tests rather than treating it immediately. This approach, sometimes called “watchful waiting,” can be appropriate for slow-growing tumours that aren’t causing symptoms.^[8]

Your overall health and fitness level also influence how well you might do with treatment. People who are generally healthy and active tend to tolerate treatments better and may have more treatment options available to them. Other factors that can affect prognosis include your age, whether you have other medical conditions, and how your body responds to treatment. It’s important to remember that statistics about prognosis are based on groups of people and cannot predict exactly what will happen to any individual person. Each patient’s situation is unique.^[1]

Survival Rate

Survival rates for lung neuroendocrine tumours differ significantly based on the specific type. For typical carcinoid tumours, which are the most common and slowest-growing type, the five-year survival rate when diagnosed at an early stage with the disease still localized is estimated to be around 85 percent to 95 percent. This means that approximately 85 to 95 out of every 100 people with early-stage typical carcinoid are still alive five years after diagnosis. However, when typical carcinoid is diagnosed at a later stage after it has spread to nearby areas or distant parts of the body, the survival rate tends to be lower.^[1]

For atypical carcinoid tumours, which are somewhat more aggressive than typical carcinoids, the five-year survival rate generally ranges from 40 percent to 70 percent. This variation reflects the fact that atypical carcinoids are associated with a slightly higher risk of spreading to other parts of the body compared to typical carcinoids. As with typical carcinoids, the prognosis is more favorable when the tumour is discovered and treated while still localized.^[1]

Small cell carcinoma, the most aggressive type of lung NET, has a considerably lower survival rate. The five-year survival rate for small cell carcinoma typically ranges from 20 percent to 30 percent. This lower rate is largely because small cell carcinoma grows rapidly and is often diagnosed at an advanced stage when treatment options become more limited and less effective. The aggressive nature of this cancer type means it tends to spread quickly to other parts of the body, making it more challenging to treat successfully.^[1]

It’s essential to understand that these survival statistics are approximate figures based on past patient outcomes and can vary based on individual circumstances. Many factors influence an individual’s outcome, including the specific characteristics of their tumour, their overall health, how they respond to treatment, and access to specialized care. Medical advances continue to improve treatment options and outcomes for people with lung NETs. Furthermore, these statistics represent averages from past years, and newer treatments may offer better results than what these historical numbers reflect. If you want to understand more about what these statistics mean for your personal situation, the best approach is to have an open discussion with your doctor or specialist nurse, who can provide information based on your specific circumstances.^[1]

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