ST. PAUL, Minn. -- A survey of patients enrolled in Minnesota's medical marijuana program shows the majority report significant benefits of participating.

About half of the 435 patients that got a survey responded. Those with cancer reported the highest benefits of the program. Others surveyed have severe muscle spasms or seizures.

About 66 per cent of patients responding to the Minnesota Department of Health survey reported significant benefits. Another 24 per cent reported mild to moderate benefits.

"They feel like they've benefited quite substantially," Tom Arneson, research manager at the Minnesota Department of Health, told . "Although a small but important proportion feel like they have not received much benefit at all from the medical cannabis, which is really something that does not surprise me too much -- it's not going to be helpful to everyone."

One-fifth of patients reported side effects such as feeling lightheaded, paranoid or sleepy.

Of those surveyed, nearly three-quarters said the state's medical marijuana program's largest drawback is that it isn't affordable.

"It is expensive and unaffordable for many parts of our population," Arneson said. "It's something that we hear about a lot, because some people are feeling like it's really benefiting them, and the cost is difficult."

Program enrollees have to pay an annual $200 fee, though some might be eligible to receive a markdown. No health plans in the state cover medical marijuana, so patients have to take care of costs.

The state says about 1,300 people have been approved for the program since it launched last year. The program right now covers just nine conditions, including Crohn's disease and cancer. In August, patients who have intractable pain will be eligible for the state's program.