Neuroendocrine tumor — an atypical tumor

Neuroendocrine tumors, also called as NET (Neuroendocrine tumors), are one of the most difficult neoplasms to diagnose. In addition, they are rare and can be found anywhere in the body. Difficulty in diagnosing this disease from the characteristics of symptoms that may resemble those accompanying a completely different illness.

What is a neuroendocrine tumor?

Neuroendocrine neoplasms are a group of neoplasms that originate from neuroendocrine cells. Neuroendocrine tumors develop from cells of the endocrine (endocrine) and nervous systems and have characteristics similar to theirs. These cells can be found throughout the body. Moreover, neuroendocrine cells have the ability to produce hormones and other biological compounds. It is estimated that in 70% of cases these tumors are located in the digestive system. They are especially common in the intestines, pancreas, and stomach.

So far, the reasons for the development of neuroendocrine tumors have not been understood. In contrast, the risk of developing neuroendocrine neoplasms increases in people who inherit the following genetic syndromes:

• Type 1 (MEN1) and type 2 (MEN2) multiple endocrine neoplasia
• Von Hippel-Lindau disease
• Tuberous sclerosis
• Neurofibromatosis

Neuroendocrine cancer — symptoms

Neuroendocrine tumors are characterized by the presence of atypical symptoms or total absence of any symptoms at all for many years. This makes them difficult to recognize. They are still one of the least understood cancers. For these reasons, their detection is a difficult task. Diagnosis of such tumor may even take 3-7 years. They usually progress slowly, but there are cases where endocrine tumors grow rapidly. In addition, there are many types of neuroendocrine tumors. However, due to the common features they show, they are treated as one group. They are most common in the lungs, appendix, small intestine, rectum and pancreas.

Symptoms largely depend on the location of the tumor. Some neuroendocrine tumors produce excess hormones, these are referred to as active neuroendocrine tumors. On the other hand, others do not produce them at all or the amount produced is not sufficient to cause symptoms of the disease. Such tumors are referred to as inactive neuroendocrine tumors.

The most common symptoms include:

• Pain as a result of tumor growth;
• A lump under the skin;
• Fatigue and weakness;
• Sudden weight loss.

In the case of active tumors — producing hormones, symptoms such as reddening and rash of the skin, diarrhea, frequent urination, increased thirst, dizziness are also observed.

Neuroendocrine tumor — diagnosis

One of the ways to classify neuroendocrine tumors is the scheme developed by the World Health Organization (WHO). It divides these tumors into three main groups

• well-differentiated neuroendocrine tumors (divided into tumors of benign and uncertain behavior);
• highly differentiated (low-grade) neuroendocrine neoplasms;
• poorly differentiated (high-grade) neuroendocrine neoplasms, which are large cell and small cell neuroendocrine neoplasms.

Additionally, mixed tumors with features of both neuroendocrine and epithelial neoplasms are also diagnosed. Classification of a given tumor to one of the categories depends on many factors, such as its size, the presence of invasion of adjacent organs or the presence of metastases.

In order to obtain a diagnosis, it is necessary to perform, inter alia, blood tests (i.e. tumor markers, which in the case of neuroendocrine tumors include endocrine-based studies). In addition, it is necessary to perform imaging tests — computed tomography, magnetic resonance or endoscopy.

Neuroendocrine tumor — treatment

Treatment measures may be aimed at curing the disease or reducing its symptoms. The decision regarding treatment requires careful examination of the tumor, which consists of determining its location, invasiveness and malignancy. One of the deciding factors is also determining whether a particular tumor is producing additional hormones. Low-grade neuroendocrine tumors that do not produce hormones may be monitored. Conversely, if the tumor is locally advanced or has metastatic changes and its growth is slow, symptomatic relief is the preferred form of treatment. Medium- and high-grade tumors are most often treated with active therapies involving early intervention.