In a major breakthrough in prostate cancer treatment, a new drug has been shown to prolong survival in patients with advanced prostate cancer.

Bayer, a German pharmaceutical company, and Algeta, a Norwegian oncology company, worked together to develop the drug, which is called Alpharadin. It treats cancers that have spread to bone -- as advanced prostate cancer almost always does -- by sending tiny doses of radiation just to those parts of the bone where the cancer has metastasized.

Alpharadin recently underwent Stage III clinical testing, and doctors found that it extended survival in patients with advanced prostate cancer from about 11 months to 14 months. The trial was stopped early as a result, because it would have been unethical not to offer the active treatment to those taking placebo, Chris Parker, a clinical oncologist at the Royal Marsden Hospital in London and one of the Alpharadin researchers, told the European Multidisciplinary Cancer Congress in Stockholm.

The trials involved prostate cancer patients, but the treatment would probably also work in patients with other types of cancer that have spread to bone.

Radiation has long been used as a treatment for cancer, but Alpharadin is novel because it is so targeted. This means it can kill cancer cells without affecting normal cells, which is the main problem with many other cancer treatments, including chemotherapy -- and as such, it has significantly fewer side effects.

It only takes a single alpha particle to kill a cell, Parker said in a press release. Collateral damage is minimized because the particles have such a tiny range -- a few millionths of a meter -- so we can be sure that the damage is being done where it should be, to the metastasis.

Chemotherapy attacks cells that divide quickly: cancer cells, but also cells in the gastrointestinal tract, bone marrow and hair follicles. This causes the common side effects of nausea, vomiting, hair loss, anemia (low red blood cell count) and weakened immune system (low white blood cell count).

Alpharadin is designed to attack only cancer cells. It does have some side effects, including nausea, but they are much milder than the effects of chemotherapy.

Compared to chemotherapy, which affects all the tissues of the body, radium-223 is highly targeted to the bone metastases, and it has a completely different safety profile, Parker said in the press release, adding that the treatment was extremely well tolerated in trials.