Dreaming of Colorectal Cancer

Colorectal cancer risks may be increased by obstructive sleep apnea

(RxWiki News) Poor sleep disturbs the body in all sorts of ways. Snoring affects our breathing, how much oxygen the body gets and how much sleep we need. And all of this may play a role in cancer risks.

Researchers have found that people who slept nine or more hours and were overweight or snored regularly had increased risks of colorectal cancer.  

Obstructive sleep apnea (repeated stopping and starting of breathing during sleep) may be to blame, according to the new study.

"Try to get 8 hours of sleep per night."

Xuehong Zhang, MD, ScD, instructor in the Department of Medicine at Harvard Medical School and associate epidemiologist at Brigham and Women’s Hospital in Boston, led the study that looked at data on more than 100,000 individuals.

The study’s goal was to determine if there was an association between how long someone slept and colorectal cancer risks. The researchers also evaluated if and how snoring and weight affected risks.

Researchers reviewed information on 30,121 men aged 41 to 79 years in the Health Professionals Follow-up Study and 76,368 women aged 40 to 73 years in the Nurses’ Health Study.  

Every other year, participants filled out questionnaires relating to, among other things, lifestyle issues and disease history. Study members estimated the number of hours they slept in a 24-hour period. They were also asked if they snored.

Over a 22-year follow-up period, nearly 2,000 people were diagnosed with colorectal cancer – 709 men and 1,264 women.

Individuals who snored regularly or were overweight and reported nine or more hours of sleep a day had between a 1.4- to two-fold greater risk of developing colorectal cancer compared to overweight or regular snorers who slept seven hours a day, the study discovered.

“Longer sleep duration was associated with an increased risk of developing colorectal cancer among individuals who were overweight or snored regularly. This observation raises the possibility that sleep apnea and its attendant intermittent hypoxemia [reduced oxygen levels in the blood] may contribute to cancer risk,” the authors wrote.

The authors suggested that this association may be due to obstructive sleep apnea which involves interrupted and difficult breathing.

Obstructive sleep apnea interferes with the quality of sleep which leads to the need for more sleep. The condition also causes intermittent hypoxemia, which animal studies have shown may increase tumor growth.

“Given the sparse data, more research is warranted to evaluate whether sleep duration or sleep quality is a novel risk factor for colorectal cancer and to understand the mechanisms behind this association,” the authors concluded.

Colorectal cancer is the third most common cancer, affecting 143,000 Americans every year, and the second leading cause of cancer deaths in the US.

The study appears in the May issue of the journal Sleep. No funding information was provided. No author disclosed a potential conflict of interest.

Review Date: 
April 30, 2013