This article belongs to the series Current cancer atlaswhere the most recognized experts about the different types of cancer that exist will explain to the readers of The Conversation what they can trigger them, what incidence they have, how they act and what are the latest advances in their detection and treatment.
Thyroid cancer is the seventh type of more common cancer worldwide and occupies the first place among endocrine origin. Its incidence has always been much greater in women, which represent 75 % of cases.
Despite its high frequency, thyroid cancer has enjoyed a fairly hopeful global survival rate. However, this data depends greatly on the cancer subtype, as well as the stage in which it is diagnosed.
The most common of all are the papillary (84 %), whose 5 -year survival rate is greater than 95 %. This good prognosis is fundamentally based on the fact that it is a slow growth tumor mode and the excellent result of the usual treatments.
At the opposite end is anaplastic carcinoma, which represents just over 1 % of all cases and is the worst prognosis, with an average survival of just 6 months.
What factors increase the risk?
Exposure to ionizing radiation is the main risk factor associated with thyroid cancer development. This relationship has been verified in people subject to certain diagnostic or therapeutic procedures that implied the use of these radiation (as can occur with the use of CT or radiotherapy), and very evident after the Chernobil nuclear accident (1986).
The risk of developing this pathology increases with the dose received and especially if it occurs in early ages such as childhood or adolescence. Added factors such as obesity or exposure to endocrine disruptors (substances that can interfere with the normal function of hormones) also seem to play an important role in the probabilities of their development.
There are other non -avoidable conditions, such as age, being a woman or the existence of genetic factors, although the latter barely suppose between 5 % and 15 % of diagnoses.
How is it detected?
In most cases, these types of tumors do not have a clear manifestation. The palpation of a nodule in the neck by the patient or the health professional during an exploration, as well as their incidental finding in image tests, are usually the starting point for diagnosis.
In recent decades the number of thyroid cancer cases has increased surprisingly. However, it is very likely that behind this increase there will be a phenomenon of overdiagnosis due to greater and easy access to detection tests, which in other circumstances would not have manifested or supposed a risk to patient’s health.
Once the presence of a nodule is suspected, thyroid ultrasound is the choice tool to assess its characteristics. Through this image technique you can study a series of key parameters in the risk assessment such as the size and shape, the definition of its edges, the presence of microcalcifications or its ecogenicity (how bright or dark it is seen).
If later a more exhaustive study is needed, an aspirative puncture with a fine needle (paaf) is guided by ultrasound. With this technique you can extract a small sample of the patient’s cells to assess more detailedly with the help of a microscope.
Despite its enormous reliability, in 20-30 % of cases the Paaf procedure can yield indeterminate results. So, molecular characterization tests could be very helpful. These allow to detect the expression of characteristic molecular markers that help classify tumors and assess their risk, avoiding unnecessary surgeries.
Classic and future treatments
Most differentiated tumors can be successfully treated by surgical ablation, called thyroidectomy. This procedure has some inconveniences, such as the possibility of damaging the recurring nerve (which would affect the function of vocal strings) or the parathyroid glands that are very close (altering calcium levels in our body). Therefore, provided it is possible, it is preferred to carry out a hemitiroidectomy, which retains part of the gland and reduces the risk of complications.
In recent years, in addition, more and more alternatives such as thermal ablation are being carried out and perfected. It consists of destroying tumor cells by applying very high temperatures through different minimally invasive techniques.
On the other hand, the radioactive iodine administration after surgery is practiced in some cases of differentiated tumors whose cells are able to capture that element. Tumor cells die by incorporating it, so it can be used to destroy possible remains of tumor tissue, given the presence of metastasis or in the treatment of patients with high risk of recurrence.
The current trend is to try to minimize interventions in exchange for increasing surveillance in those cases whose tumor characteristics allow it, such as very small and low -risk papillary carcinomas.
For difycile cases
Additionally, new approaches are being developed to those types of thyroid cancer with the worst prognosis or lower treatment options. One of them is redifferentiation therapy, in which it is about restoring the susceptibility of tumor cells to the radioactive iodine in those cases where it has been lost.
Another option is the use of different inhibitors of the kinase tyrosine enzyme, with encouraging results in some cases in which it has allowed to surgically intervene tumors that were considered unressesy.
Advances in molecular diagnosis, the application of artificial intelligence and the development of directed therapies could revolutionize thyroid cancer management in the coming years, improving the survival of those with the worst prognosis and optimizing the results of clinical interventions.
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