International researchers said they have made steps toward understanding why the most commonly used drugs for osteoporosis worldwide, known as bisphosphonates, may also prevent some kinds of lung, breast and colon cancers. If confirmed in clinical trials, the findings could accelerate the use of drugs such as alendronic acid (Fosamax), zoledronic acid (Reclast, Zometa) and ibandronic acid (Boniva) to prevent tumours or treat them in their early stages, according to two studies published on Monday in the Proceedings of the National Academy of Sciences. Bisphosphonates work by blocking the abnormal growth signals that are passed through a family of proteins known as human EGF receptors (Her), the studies found. This, in essence, shuts down the cancer's ability to spread, and is of particular importance because Her cancers tend to be more aggressive than other types. "Our study reveals a newfound mechanism that may enable the use of bisphosphonates in the future treatment and prevention of the many lung, breast and colon cancers driven by the Her family of receptors," said lead study author Mone Zaidi, who is a professor of medicine at the Icahn School of Medicine at Mount Sinai in New York. "Having already been approved by the Food and Drug Administration (FDA) as effective at preventing bone loss, and having a long track record of safety, these drugs could be quickly applied to cancer if we can confirm in clinical trials that this drug class also reduces cancer growth in people," Zaidi said. Previous research has shown that some breast cancer patients have lived longer lives while taking the medications to prevent bone loss.