In my previous post I forgot to mention an other uncertainty about Zometa (& other drugs in the same class of bisphosphonates) which makes some oncs leery to prescribe it in frequent doses for extended periods of time: no one is sure how long the drug stays in the bones but it is probably measured in years if not permanently.
Zometa does not reestablish the normal process of bone resorption & bone formation upset by bone cancer which is described as follows:
"Bisphosphonates inhibit the activity of bone-destroying cells called osteoclasts. Normally, osteoclasts work in harmony with bone-forming cells called osteoblasts in order to rebuild areas of bone that need replacing."
As a result there is uncertainty about the long term quality of bones laced with long lasting bisphosphonates even if they reduce initially the risk of fractures.
This is why Zometa is not yet approved in several countries for osteoporosis.