Overweight, obesity and cancer: epidemiological evidence and proposed mechanisms

The prevalence of obesity is rapidly increasing globally. Epidemiological studies have associated obesity with a range of cancer types, although the mechanisms by which obesity induces or promotes tumorigenesis vary by cancer site.

These include insulin resistance and resultant chronic hyperinsulinaemia, increased bioavailability of steroid hormones and localized inflammation. Gaining a better understanding of the relationship between obesity and cancer can provide new insight into mechanisms of cancer pathogenesis.

Obesity, Sleep Apnea Syndrome, and Rhythmogenic Risk

Obstructive sleep apnea is a common disorder and affects approximately 4% of middle-aged men and 2% of middle-aged women. Obstructive sleep apnea is clearly associated with obesity, with more than 50% of patients having a body mass index > 30 kg/m2. Substantial evidence identified obstructive sleep apnea as risk factor not only for excessive daytime sleepiness and road traffic accidents, but also for increased cardiovascular morbidity and mortality.

In addition, all kinds of arrhythmias have been observed in patients with sleep apnea ranging from asymptomatic sinus bradycardia to sudden cardiac death. Approximately 5–10% of patients with obstructive sleep apnea show marked apnea-related bradyarrhythmias due to enhanced vagal tone and pronounced hypoxia. Therapeutic options in obese patients with obstructive sleep apnea include consequent weight loss and nasal continuous positive airway pressure (CPAP) ventilation as the therapy of first choice. Weight reduction and effective nasal CPAP therapy significantly decrease cardiovascular morbidity and mortality and eliminate sleep-related bradyarrhythmias in 80–90% of patients obviating the need for pacemaker implantation in these patients.

Wolfram Grimm and Heinrich F. Becker
(1)  Department of Internal Medicine and Cardiology, Hospital of the Philipps University of Marburg, Germany
(2)  Department of Respiratory Medicine, Hospital of the Philipps University of Marburg, Germany
(3)  Department of Internal Medicine and Cardiology, Philipps University Marburg and University Hospital Giessen and Marburg, Baldingerstraße, 35033 Marburg, Germany

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