Medical scientists from Deakin University say they have developed a powerful drug combination to treat prostate cancer patients that would have no side effects.

Australian scientists have developed a "breakthrough" in prostate cancer treatment after discovering a protein found in milk reduces the toxicity of an existing chemotherapy drug.

The powerful new treatment would have little to no side effects, according to the scientists from Victoria's Deakin University.

In a study published in international journal Scientific Reports, the scientists found that when coupled with milk protein lactoferrin, drug Doxorubicin (Dox) can be delivered directly into the nucleus of prostate cancer cells and will kill those cells as well as drug resistant cancer stem cells.

Within 96 hours, all the cancer cells - grown in a culture dish in a laboratory - were dead after mice were treated with the drug treatment.

Lead researcher Dr Rupinder Kanwar says not only did the drug combination kill the cancer cells, it also led to cell repair to vital organs damage as a result of Dox.

Doctors stopped using Dox to treat prostate cancer because of the side effects. It caused toxicity to the heart, brain, kidneys and led to cardiac arrest and heart failure.

However, it could possibly be reintroduced as a result of this new study, Dr Kanwar said.

"Prostate cancer is one of the few cancers where chemotherapy is not the primary treatment. This is because these particular cancer cells are able to flush out the drug and become resistant to it, while the administered Dox continues to kill off the body's normal cells resulting in a range of side effects, the most damaging of which is heart failure.

"With this latest study we have shown that by coupling Dox with lactoferrin the cancer cells take in the drug rather than pump it straight out."

Lactoferrin is an iron-binding protein found in cow milk and human milk. It is known for its immune boosting and antimicrobial properties, making it an important part of the body's protection against infection. It is also added as a key ingredient in baby formula.

The main goal for the researchers now is to conduct human trials.

"The results of our research to date show great promise that we could soon develop personalised medication for cancer patients," Dr Kanwar said.