Apnea, a nightmare that not only takes away the dream

Apnea is respiratory disorder associated with problems such as hypertension, stroke, or myocardial infarction, but a new research has just demonstrated that it is also related to the aggressiveness of melanoma.

It can be likened to a nightmare for several reasons. But obstructive sleep apnea is much more than that. There is increasing evidence that the disorder is intimately related to diseases having nothing to do with the rest, such as hypertension or cancer. In fact, a research has just demonstrated the links with a greater aggressiveness of melanomas.

While we sleep the body’s muscles, including those that take care of the air to reach the lungs, relax. Normally, and despite this relaxation, the throat remains open enough to allow breathing. But in some cases this does not happen and the airway is blocked by interrupting the passage of air and causing small awakenings that usually go unnoticed.

When there is obstructive sleep apnea, these pauses, whose duration varies, occur more than five times an hour (30 times or more in the most severe cases) and usually end with a loud sound from which the person breathes again. The sufferer does not realize, but these episodes, which are accompanied by snoring, not only alter their sleep patterns but also cause an intermittent but considerable decrease in their levels of oxygen in the blood, which sets in motion a whole cascade of metabolic alterations with very extensive ramifications.

It has been shown, for example, that with each episode of apnea the organism causes, among other effects, a ‘discharge’ of the sympathetic system that raises blood pressure and increases the heart rate frequency. The constant repetition of this pattern means that, in the medium term, hypertension becomes chronic and appears during the day, as demonstrated by numerous epidemiological studies. In fact, some studies suggest that increases of up to 30 mm Hg in blood pressure may occur.

There is great evidence of the connection between sleep apnea and hypertension. The main cause of this phenomenon is the lack of oxygen that occurs with each episode of apnea. Intermittent hypoxemia initiates mechanisms similar to those that occur in cardiovascular diseases. In that sense, although lower than in the case of hypertension, there is also considerable scientific evidence linking apnea with a higher incidence of heart attacks and strokes by similar mechanisms.

The team of researchers was just studying cardiovascular mortality in a group of elderly people with sleep apnea when he accidentally observed a striking increase in the number of deaths due to cancer. In that sample of patients, deaths from malignant tumors tripled to those found in the control group, which put the researchers on the track of a possible links between the two diseases.

After verifying that there was hardly any data of this possible association in the scientific literature, the researchers went to work and decided to investigate on their own. First, analyzing historical series of patients in the US and then carrying out their own prospective analysis.

In parallel with the first observation in 2012 a group of researchers from the University of Barcelona observed in melanoma models replicated in mice that, in animals subjected to intermittent hypoxemia similar to that produces apnea, the tumors grew at a rate that doubled that of the control group. In addition, the number of metastases was also significantly higher. With all these data in hand, a group of experts set out to try to find solid evidence of this relationship. Therefore, after conducting a pilot study with good results, they followed 443 patients with melanoma trying to uncover how the number and severity of possible respiratory disorders translated into a higher rate of cancer growth. The work involved 30 hospitals throughout Spain and the University of Chicago, which involved the collaboration of more than 150 people among pulmonologists, dermatologists, oncologists, pathologists, neurophysiologists and other laboratory personnel, basic research and nursing. The results showed that sleep apnea is associated with an increase in the aggressiveness of malignant cutaneous melanomas. The presence of sleep apnea in a patient with melanoma means that it has twice more chances that their melanoma is more aggressive than in patients suffering from melanoma without sleep apnea. The aggressiveness of melanoma seems to be more intense in people under 55 years of age for reasons unknown at the moment. The greater the degree of severity of sleep apnea, the greater the degree of aggressiveness of melanoma appears to be. The study also revealed a prevalence of apnea in much larger sample of melanoma.

The researchers study the possible mechanisms that are behind this association and for now have only clues. There is evidence that the lack of oxygen alters the immune system and makes certain cells that normally have an antitumor behavior change profile and happen to act as promoters of cancer. But in addition, there is also evidence that sleep fragmentation also causes hormonal alterations capable of stimulating tumor growth. Patients with sleep apnea appear to be exposed to two distinct stimuli that independently promote tumor growth. What it is not known is whether that effect additive or synergistic.

Until the research yields new results and clarifies the observed relationship, available data are sufficient to alert all those professionals who control cancer patients, including melanoma, to ask them about symptoms related to nighttime rest, especially sleep apnea syndrome, and if it exists, to refer their patients to the corresponding ‘sleep units’ to be studied and treated if necessary. The usual treatment is the use during sleep of a CPAP, a device that exerts pressure of compressed air and allows to maintain open the airway while the patient sleeps. In general the search for respiratory disorder should be increased since between 6% and 10% of the middle-aged population (obesity is the main risk factor) has sleep apnea, although more than 80% is not diagnosed.

Since the affectation that produces is systemic and there are many other disorders that are ‘tied’ to her. In addition to hypertension, cardiovascular disorders and cancer, there are also data that have suggested a possible link between apnea and some neurocognitive disorders, the development of renal failure or an increased risk of traffic accidents, among others.

The good news is that the clinical approach to the problem is very effective. In addition to the benefits of implementing hygienic dietary measures for weight management and improving sleep habits, it has been shown that CPAP treatment improves quality of life, daytime sleepiness, mental activity or hypertension (compared to other cardiovascular diseases, the data are still controversial). In addition, there is also much evidence that this treatment prevents traffic accidents and reduces health costs.

Apnea has traditionally been associated with the male gender. The most common profile in the consultations is the middle-aged man who is accompanied by his wife, who has detected snoring and breathing pauses during sleep. However, the reality is that it is not just a disorder of men. At least 6% of women in the general population have sleep apnea. The causes of this reality are multiple: on the one hand, the airways of women have characteristics different from those of men, which protects them against apnea, at least until menopause. But in addition, the truth is that they go more alone to the doctor, so there is no observer to ask. And they complain less of the typical symptoms, such as snoring or daytime sleepiness, while on the contrary, they usually manifest other problems, such as headache, fatigue or depression, which in many cases does not reflect the possibility of sleep apnea in these patients. Until now, the vast majority of the studies had practically analyzed exclusively male patients, so the peculiarities of the woman had not been taken into account.