She's 74 and the few recent YouTube videos I've seen of her in concert have not been kind to her legacy. (I still think her Stairway to Heaven cover is the best ever)

Cancer sucks, no two ways about it, but I'm also thinking that this is another casualty of the economy, people just aren't paying for entertainment like they used to. Seems there's more than a few acts cancelling tours due to low ticket sales, although there's always another reason stated.