Anti-choice lies on billboards

In my town I'm seeing anti-choice billboards that imply that abortion causes breast cancer. They show a teenage girl, the phrase, "Why didn't they tell me?" and a web address with "cancer" in it.

There is no link between abortion and breast cancer. The topic has been researched again and again and there's nothing. It's just a lie, a myth, a scare tactic, a bogeyman.

Why isn't someone suing these people? Why isn't the Canadian government making them back down on their lying claims?