Preventing bone breaks in cancer patients is one thing, but preventing the tumors from metastasizing in the first place could have been worth an additional $1 billion in sales.

Unfortunately, it looks like the hopes of those additional sales for Novartis' (NYSE: NVS) Zometa mostly vanished yesterday after the company presented data comparing Zometa to placebo in breast cancer patients.

There was no disease-free survival advantage to taking Zometa for the entire population. If you only look at the patients who have already been through menopause, however, there was a clear overall survival advantage to taking Zometa.

Novartis had already applied to market the drug for breast cancer patients of all ages in Europe and the U.S., so those applications will have to be withdrawn. It's possible Novartis will be able to use the subset analysis -- it was preplanned -- as a basis for new applications to treat older women with breast cancer. Something is better than nothing, I guess.

Zometa belongs to a class of drugs called bisphosphonates that keep bone-destroying cells called osteoclasts at bay. Merck's (NYSE: MRK) Fosamax and GlaxoSmithKline's (NYSE: GSK) and Roche's Boniva are in the same class, but they're only approved to treat osteoporosis, not to prevent breaks in the cancer setting. That might be because they aren't as potent as Zometa.

Amgen (Nasdaq: AMGN) has a new bone drug, denosumab, which blocks osteoclasts in a completely different way. It's sold under two names: Prolia for osteoporosis and Xgeva for cancer. The latter beat Zometa in a couple of head-to-head trials, so it's expected to compete well. We'll get an early look at the launch when Amgen releases fourth-quarter earnings early next year.

Like Zometa, Xgeva's largest opportunity could be in preventing cancer from spreading to the bone rather than just treating it. Since they inhibit different proteins, but essentially work under the same ultimate mechanisms -- inhibiting osteoclasts -- it's hard to know how Zometa's failing affects Xgeva's chances.

We'll know soon enough. Data from the cancer prevention trial for Xgeva are expected to be available shortly.

What's better than buy and hold? Bryan Hinmon thinks he's found it.

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Fool contributor Brian Orelli, Ph.D., doesn't own shares of any company mentioned in this article. The Fool has a disclosure policy.