According to the data, the incidence of this disease would have tripled in recent decades, but perhaps it only has to do with advances in diagnostic techniques.
June 1922. Given the serious health situation, the Spanish King Alfonso XIII toured Las Hurdes (Extremadura) together with the doctor and writer Gregorio Marañón. Located in the north of the province of Cáceres, this region was the setting eleven years later for the famous documentary Las Hurdes (Land Without Bread), directed by Luis Buñuel. A land awash in poverty and disease.
Those images show one of the biggest health problems of the time: goiter and endemic cretinism. And the cause of both is closely related to the functioning of our thyroid gland.
A goiter is nothing more than an increase in the size of said gland, which in the face of an extreme lack of iodine (an essential element for manufacturing thyroid hormones) tries to compensate for the deficiency by increasing its size. This deficit, in its most serious state, gives rise to cretinism, which is characterized by developmental abnormalities and significant intellectual deficiency.
Frame from Las Hurdes, land without bread (Luis Buñuel, 1933), in which a mother with a goiter is seen with her baby in her arms.
From Las Hurdes de Buñuel to our times
The lack of iodine was not and is not the only cause of hypothyroidism, as the lack of thyroid hormones in our body is called, which continues to be one of the most frequent endocrine pathologies also in our times.
Although fortunately, those images of Buñuel are now behind us: the tools available today, in terms of prevention, diagnosis and treatment, have made it a much more controlled and manageable issue.
If there is a health problem that worries us all, it is cancer, whose origin can also be in the thyroid gland. Many media have spent years warning of the increase in the number of people who suffer from it.
In fact, thyroid cancer is the most common form of endocrine tumor worldwide, and the number of people diagnosed has tripled in recent decades. The reason for this significant increase continues to be debated among the scientific community.
Although there is no unanimous answer, it seems that technological advances and greater access to different diagnostic methods may be behind these numbers. This can mean that we are suffering from a phenomenon of “overdiagnosis”: the detection of cases that, if they had not been identified, would not have generated symptoms or negatively affected the patient’s life. In other words, diagnoses that, if they had not occurred, would have allowed us to live the same way, but much calmer in our ignorance.
Why do we detect more cases?
Simply because there are increasingly accessible and sensitive tools, such as thyroid ultrasound and biopsies performed by fine needle aspiration. These techniques make it possible to detect tumors in very early stages that would otherwise probably have gone undetected without causing any symptoms.
There are different types of thyroid cancer: from the most common and harmless to the rarest and most aggressive. In fact, the increase in cases observed in the last decades corresponds almost exclusively to a specific subtype. We are talking about papillary cancer, which is the modality that is most frequently found in its subclinical form, that is, before producing any symptoms.
One more fact that supports the theory of overdiagnosis is that the number of deaths from thyroid cancer, far from increasing, has stabilized, and even decreased, in recent years.
Are women more likely to develop thyroid cancer?
The numbers are clear: the diagnosis of thyroid cancer is between 3 and 4 times higher in women than in men. Traditionally it has been thought that some hormonal factors could be behind this difference, but there are not sufficiently solid data to corroborate the hypothesis.
Even some of the latest studies seem to indicate that this observation is somewhat simplistic. The casual finding of thyroid tumors in autopsies performed on people who died from other causes is relatively common. And the percentage of cadavers in which these findings occur remains more or less constant over time, with no difference between the sexes.
It is simply believed that women are diagnosed more frequently due to the different medical surveillance to which they are subjected and the unequal use of health care by both sexes. A question that seems more sociological than physiological.
What weight do environmental factors have?
Although it is still only speculation, there is a suspicion that not everything is to blame for overdiagnosis. Some data points to factors such as obesity, a condition closely linked to thyroid cancer. However, it is not yet clear if it is also behind the increase in cases in recent decades.
The influence of endocrine disruptors, chemical substances capable of interfering with the normal functioning of our hormones, in this case, thyroid hormones, is also being studied.
These types of compounds have been described in countless elements in our environment, such as pesticides, industrial solvents, plastics, medicines and even food. The list of substances classified as endocrine disruptors is constantly changing. Some of them have been recently identified and there is hardly any data on their safety levels or long-term effects.
In addition, it is known that in many cases it is the mixture of some of these compounds that can be harmful, making it even more difficult to obtain solid conclusions in this regard.
As we can see, there are many questions that the scientific community is still trying to answer. Meanwhile, there are measures with plenty of scientific evidence that can help us keep our thyroid gland in perfect condition.
Maintaining a balanced diet and a healthy lifestyle, away from obesity and a sedentary lifestyle, is undoubtedly the best formula available to us to prevent pathologies such as thyroid cancer.
This article has been published in ‘The conversation‘.
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