Neuroendocrine tumors are rare cancers, with an incidence of between five and six cases per 100,000 inhabitants in Spain, which usually appear in young people between 30 and 50 years old.
Although tumors such as breast, prostate or colon cancer are well known among the population, the same cannot be said for other types of less frequent cancers, such as neuroendocrine tumors (NETs), which affect the glands or devices of the neuroendocrine system (pituitary, thyroid, adrenal glands and 10% of the pancreas) and cells of the endocrine system in general (located mainly in the gastrointestinal tract and respiratory tract).
In Spain, explains Dr. Enrique Grande, head of the Medical Oncology Service of MD Anderson Cancer Center Madrid and one of the leaders in the treatment of NETs in our country, "although there are no accurate records, it is estimated that the incidence is between five and six cases per 100,000 inhabitants thanks to the extrapolation of European data ". Given these figures and the lack awareness among the population, dates such as World TNE Day, which is celebrated on November 10, become even more important.
On the incidence in other countries, the specialist points to a slightly higher incidence in the countries of northern Europe, a figure he attributes to "a greater sensitivity towards the diagnosis of this pathology and a greater number of reference centers on the disease " In Spain, for example, there are no reference centers with the levels required in Europe because they do not reach the minimum number of patients required by law, a problem motivated by the low incidence of NETs and which at the same time affects the difficulty of accumulating professional experience in the treatment of the disease.
In addition, this also hinders research. "The problem lies in bringing together enough patients with these characteristics; It is very difficult to do research if you have five patients, "says Dr. Grande.
As many TNE as patients diagnosed
Since NETs can have their primary origin in very diverse locations of the organism, including a percentage of the pancreas, the disease behaves very differently in each patient. To this circumstance, which very much determines how the tumor will behave and its prognosis, we must also add the aggressiveness of the cancer according to its degree of histological differentiation (greater differentiation -G1-, better prognosis) and whether the tumor does or does not produce hormones, that is, whether or not it is functioning.
Speaking about hormone production, Dr. Grande emphasizes above all the enormous number of functions that a hormone can have and, therefore, the many differential symptoms they can cause and that vary from a rise or fall in sugar to diarrhea, high blood pressure or a skin rash. "I do not know two patients with NET who have the same behavior," says the specialist, who also explains that the age of these patients is also variable, ranging from 30 to 50 years.
The problem of a tumor with such few differential symptoms is that the diagnosis becomes very complicated. "It is very difficult for the primary care physician to suspect from the beginning that he is looking at a NET, so the patient begins a pilgrimage of diagnostic tests until, one day, the definitive test arrives," acknowledges Dr. Grande. The other route to the oncologist, continues this expert, is through the surgery, internal medicine or emergency services. "As we increasingly do ultrasounds and CT scans for banal pathologies, sometimes TNE are diagnosed in early stages incidentally, before they can show symptoms, "explains Dr. Grande. In these cases of early diagnosis, and also taking into account the degree of histological differentiation, the cure rate can reach up to 90%.
NETs require multidisciplinary treatment
Given the wide variety of NETs, multidisciplinary treatment is even more relevant in these tumors. Thus, in the first place, argues Dr. Grande, "it is important to have a very good pathologist to diagnose, typify, extract and express all the possible information of the tumor from the histological point of view". After which, it is important that an endocrinologist describes the functionality or not of the tumor in the production of hormones. Once this first diagnosis is made, it is essential that a radiologist define the exact extent of the tumor and that a nuclear medicine specialist take charge of the imaging tests.
In addition, for the treatment of the tumor, it is important to have a surgeon and, if pharmacological therapy is required, a medical oncologist specialized in TNE. The normal treatment of these tumors is usually based on somatostatin analogs (intramuscular or subcutaneous injections that are fairly well tolerated) and usually does not include chemotherapy.
At least this was the usual treatment, since only a month ago the European Commission approved a new treatment, radionuclides. "These new drugs are like somastatin analogs, but linked to a radioactive atom," explains Dr. Grande, who continues to point out that they work "by binding to the membranes of neuroendocrine cells and releasing their radioactivity locally."
But this approval does not only have a therapeutic purpose, but also a diagnostic one. By joining the radionuclides to a gallium atom, a chemical element that releases a phosphorescent color, "it is possible to identify the location of the tumors in a much more specific way", emphasizes this specialist in TNE, who highlights the great advantage of having of a Gallium PET in MD Anderson Madrid, both at the level of specificity and sensitivity for the differential diagnosis of these complicated tumors.