Lance Mackey out to prove the naysayers wrong.

Both knees are shot, injected with synthetic cartilage until he can have surgery next summer. His right arm is still healing from a major operation to fix a staph infection. He continues to deal with other side effects of cancer.

But Lance Mackey is gunning for his fourth consecutive win in the 1,000-mile Iditarod Trail Sled Dog Race, which started Sunday in Willow.

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Mackey speaks openly about using medical marijuana on the trail as a post-cancer painkiller and appetite enhancer. He also talks about facing a misdemeanor count of marijuana possession after being found with a small amount at the Anchorage airport in January, after his medical marijuana card had expired.

For this race, he said he's staying away from pot. That's because the Iditarod for the first time is testing mushers for alcohol and illegal drugs, although a provision allowing testing has been on the rule books since 1984. Officials say exemptions include Marinol, a government-approved drug that contains the active ingredient in marijuana, but Mackey said he's even laying off on his own prescription.

Mackey believes the policy is directed at him. He said other competitors have complained that pot has given him an advantage.

"We're going to prove some people wrong," he said. "The dogs are the ones doing all the work, for the most part. I don't see much of an argument beyond that."

Stan Hooley, executive director of the Iditarod Trail Committee, said it would be "hard to deny" speculation that the implementation is targeted at Mackey.

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