Hematology/Oncology

Those who are prescribed high doses of certain common sleeping pills have a significantly increased risk for developing cancer, according to study findings.

The risk for developing lymphomas and lung, colon or prostate cancers associated with sleeping pills was greater than the risk associated with smoking, the researchers said.

Daniel F. Kripke, MD, of the Scripps Clinic Viterbi Family Sleep Center in La Jolla, Calif., and colleagues reviewed the medical records of more than 34,000 patients served by the Geisinger Health System in Pennsylvania.

They compared 10,531 patients who were prescribed various types of sleeping pills — including benzodiazepines, non-benzodiazepines, barbiturates and sedative antihistamines — with 23,675 control patients who were not prescribed sleeping pills.

The participants were followed for an average of 2.5 years, from January 2002 to January 2007.

The researchers matched the patients for age, gender, lifestyle factors and underlying health problems. They also took weight, ethnicity and previous cancer diagnosis into account.

Those who were prescribed 18 to 132 sleeping pills a year were 20% more likely to be diagnosed with cancer (HR=1.20; 95% CI, 1.03-1.40), and those who were prescribed more than 132 doses per year were 35% more likely to be diagnosed with cancer (HR=1.36; 95% CI, 1.18-1.55), the results showed.

HRs for incidence of specific cancers varied:

• Lymphoma (HR=2.99; 95% CI, 2.11-4.25).
• Lung (HR=2.97, 95% CI, 2.20-4.01).
• Esophageal (HR=2.51; 95% CI, 1.01-6.25).
• Colon (HR=1.61; 95% CI, 1.21-2.13).
• Prostate (HR=1.39; 95% CI, 1.09-1.76).
• Breast (HR=1.13; 95% CI, 0.91-1.39).
• Melanoma (HR=0.83; 95% CI, 0.55-1.26)
• Bladder (HR=0.68; 95% CI, 0.40-1.14).

“It is possible that patients receiving hypnotics experienced more medical care than non-users, providing greater surveillance and potential cancer detection,” Kripke and colleagues wrote. “However, it would be hard to imagine how greater surveillance of hypnotic users could explain two- to threefold higher HR for some cancers with no excess mortality for other cancers, whereas specific biological effects of hypnotics would more plausibly explain the differences in HR between cancers.”

The results also demonstrated that those who were prescribed sleeping pills have a higher risk of death from any cause. The risk increased with dosing, researchers said.

Those who were prescribed up to 18 doses of sleeping pills a year were more than 3.5 times as likely to die compared with those who were prescribed none (HR=3.60; 95% CI, 2.92-4.44), whereas those who were prescribed more than 132 doses per year were more than five times as likely to die (HR=5.32; 95% CI, 4.50-6.30).

The results were not attributable to pre-existing disease, the researchers said.

The data suggest that alternatives to common sleeping pills may be warranted, they said. The benefits must be weighed with the evidence of risks, and it may be time to “reconsider whether even short-term use of hypnotics, as given qualified approval in National Institute for Clinical Excellence guidance, is sufficiently safe.”