Intermittent hypoxia increases melanoma metastasis to the lung in a mouse model of sleep apnea. 
Obstructive sleep apnea (OSA) has recently been associated with an increased risk of cancer incidence and mortality in humans.  Experimental data in mice have also shown that intermittent hypoxia similar to that observed in OSA patients enhances tumor growth.  The aim of this study was to test the hypothesis that intermittent hypoxia mimicking OSA enhances lung metastasis.  A total of 75 C57BL/6J male mice (10-week-old) were subjected to either spontaneous or induced melanoma lung metastasis.  Normoxic animals breathed room air and intermittent hypoxic animals were subjected to cycles of 20s of 5% O2 followed by 40s of room air for 6h/day.  Spontaneous and induced lung metastases were studied after subcutaneous and intravenous injection of B16F10 melanoma cells, respectively.  Compared with normoxia, intermittent hypoxia induced a significant increase in melanoma lung metastasis.  These animal model results suggest that intermittent hypoxia could contribute to cancer metastasis in patients with OSA.