Right-to-die organizations in Switzerland assisted in suicides of foreigners from 31 different countries between 2008 and 2012, accounting for almost a third of country's assisted suicides.

Swiss researchers found 611 people traveled to Switzerland for the "sole purpose of committing suicide," according to a report published online in the Journal of Medical Ethics. Travelers from outside the country seeking treatment were referred to as "suicide tourists," and their numbers doubled in that four-year time period.

"In the UK, at least, 'going to Switzerland' has become a euphemism for [assisted suicide]," the study authors wrote. "Six right-to-die organizations assist in approximately 600 cases of suicide per year; some 150-200 of which are suicide tourists."

The patients' ages ranged from 23 to 97, but the average was 69 years old. Women "tourists" accounted for 58.5 percent of the suicides, and were 40 percent more likely to choose assisted suicide in Switzerland than men, according to the study.

About half suffered from some neurological conditions like paralysis, motor neurone disease, Parkinson's disease and multiple sclerosis. Others suffered from cancer, rheumatic disease or cardiovascular disease, and about a third had more than one condition.

Citizens from Germany and the UK made up almost two thirds of the total, and Italy and France saw their numbers spike dramatically. Switzerland assisted four Italian national cases in 2009 and 22 in 2012. French cases went up from seven in 2009 to 19 in 2012.

Virtually all the patients took a sodium pentobarbital cocktail. 

"The phenomenon of suicide tourism is unique to Switzerland," the study's authors wrote. "Assisting suicide is not clearly regulated by law and... no rules exist that regulate under which conditions someone might receive assisted suicide."

The study cites Oregon as a place with strict regulations. The U.S. state enacted the Death with Dignity Act in 1997 that allowed physician-assisted suicide with certain restrictions. The patient must initiate the request and be diagnosed with a terminal illness by a physician. Two witnesses must confirm the request, and one cannot be related to the patient or entitled to the patient's estate, and they cannot be the physician or employed by a health care facility caring for the patient.