Intermittent hypoxia enhances cancer progression in a mouse model of sleep apnoea

To the Editors: Obstructive sleep apnoea (OSA) is a very prevalent syndrome that induces or aggravates cardiovascular, metabolic and neurocognitive disorders. Among the various challenges imposed on a patient by OSA as a consequence of apnoeas (sleep disruption, increased inspiratory efforts and recurrent hypoxaemia), intermittent hypoxia plays a major role in the pathophysiology of this sleep breathing disorder. It has been well established that hypoxia plays an important role in regulating the various stages of tumour formation and progression [1]. Accordingly, the aim of the experimental study reported here was to test the hypothesis that high-rate intermittent hypoxia with a time course similar to that found in OSA (one or more hypoxic event per minute) enhances tumour growth. To avoid the interaction of any comorbidity, this investigation was carried out in a well-controlled animal model where the main variable under study was intermittent hypoxia. This study, which was approved by the Ethical Committee for Animal Research of the University of Barcelona (Barcelona, Spain), was conducted in 15 pathogen-free male C57BL/6J mice (25–30 g) using a conventional murine melanoma model consisting of tumour induction by subcutaneous injection of 106 B16F10 melanoma cells (ATCC-CRL-6475; American Type Culture Collection, Manassas, VA, USA) in the left flank region of the mouse [2]. This is a widely used cancer model in experimental research [3, 4], which has a response to hypoxia that is representative of a variety of cancer types …