Obstructive sleep apnea can be related to the proliferation of cancer cells.

-The cancerous melanoma tumors found in an animal model of obstructive sleep apnea tend to contain more dead cells, which is associated with a type of cancer more aggressive

-the weight of the tumor and necrosis in the Group of intermittent hypoxia mice were nearly two times higher than in tumors of the Panel control.

Spain, 2011-August A new study has found clues linking the intermittent interruption of respiration that occurs in patients with obstructive sleep apnea with a greater proliferation of melanoma cells and increased tumour growth. The study with mice, also revealed that the cancer cells were found in the models with simulation of apneas contained more dead cells, suggesting that the tumour process is more aggressive.

It is the first study that concludes that a high rate of lack of oxygen, also called hypoxia, intermittent produces an increase in the growth of tumors. Hypoxia is a recurring symptom in obstructive sleep apnea and may be the cause of an increased risk of cardiovascular problems such as hypertension, in the same way that daytime sleepiness produced a low quality of life.

“Although previous studies in animals have shown that the continuing lack of oxygen plays an important role in the regulation of the various stages of formation and tumor progression, the results obtained from studies in humans including patients with apnea are not easy to interpret because there are other possible confounding factors”, especially obesity. For this reason, this study controlled in a mouse model has enabled us to ensure that the only variable in study was intermittent hypoxia ”, explains researcher Ramon Farré, Professor of the unity of Biophysics and bioengineering of the Faculty of Medicinica of the Universitat de Barcelona-IDIBAPS and member of the dream of SEPAR area.

It is well known that continuous hypoxia promotes the growth of cancer cells and tumors. However, there are no data on the effects of changes in the fast pace of the oxygenation of the cancer sleep apnea.
The results of this study could have future clinical implications if the result is confirmed in studies on a large scale in human

In this study, the mice injected with melanoma tumor cells were divided into two groups. In the first group, the mice were exposed to intermittent hypoxia that simulated of the sleep apnea, where oxygen was restricted for 20 seconds with a period of repetition of 60 cycles per hour for six hours a day, and normal levels of oxygen for the rest of the day. In the second group, the mice received normal levels of oxygen. The tumor volume was measured throughout the 14-day study. At the end of the study period, all the mice tumors were removed and heavy, and the degree of necrosis of various tumors was measured to determine the aggressiveness of different tumors found.

The results showed that while the volume of the tumor had steadily increased over time, both intermittent hypoxia and the control group, the increase was greater in mice subjected to hypoxia intermittent, the weight of the tumor and necrosis in the intermittent hypoxia group were almost two times the tumors in the control group ”, stated Professor Farré.

With the limitations of any studies with animal models, these results suggest that intermittent hypoxia that characterizes the obstructive sleep apnea may increase the growth of tumors. Although on the basis of previous studies that connect hypoxia continuous growth tumor outcomes were not totally unexpected, had not shown that a link there is between specific breathing abnormalities of tumor progression and sleep apnea. This work, partially funded by SEPAR, he was selected for presentation at the Symposium scientific discoveries of the year ” during the recently held Conference of the American Thoracic Society, and will be published in the European Respiratory Journal.

A line of future research would be to assess if the intermittent hypoxia also causes the initial formation of tumors and promotes metastasis of tumors of a body to another. Extensive epidemiological studies may also determine if there is a relationship between cancer incidence and severity of apnea. It is also known that obesity increases morbidity and mortality from cancer, and is not clear to what extent the intermittent hypoxia and obesity, very present in patients with sleep apnea, can interact to increase cancer in patients with apnea.

As indicated by Dr. Josep Maria Montserrat of the Hospital Clínic of Barcelona and coordinator of the research programme integrated dream of SEPAR, co researcher of the study, additional studies are needed to clarify these issues without a doubt. If the current results in an animal model is confirmed by additional clinical research, the impact on public health of the obstructive sleep apnea may be larger than is currently known.