A diabetes drug has been found to slow the growth of lung cancer cells and make them more vulnerable to radiation, research at McMaster University has found.

Metformin, a drug that is meant for diabetes can play a part in helping treat lung cancer, says Dr. Theodoros Tsakirdis, an assistant professor of Oncology at McMaster University, and a radiation oncologist at the Juravinski Cancer Centre.

"We realized over time that it actually influences molecular mechanisms of cancer cell growth," says Tsakirdis. "The reason we have done the research we have done is because we are looking at the mechanisms of action of radiotherapy on cancer cells."

Currently Metformin is being tested on mice, meaning clinical trials won't start for a while, if at all.

The goal of Metformin

Tsakirdis says the goal is to enhance the effects of radiation by making cancer cells more vulnerable to the treatment, killing more cancer cells with less radiation.

"The problem in lung cancer is that we give people very high doses of radiation to the chest together with chemotherapy, which still can not cure people," says Tsakirdis. "Only 15 to 17 per cent of people will survive five years after diagnosis of locally advanced lung cancer."

Tsakirdis says patients who are at this stage of cancer are also likely to be unwell, making chemotherapy difficult or impossible to tolerate.

Tsakirdis tested many different drugs in looking for one that allows for less use of radiation, but at the same having the effects amplified.

"We've been looking at different ways of doing this and we've worked with a number of drugs but Metformin seems to be the winner in this situation," says Tsakirdis. "Lung cancer seems to have a particular sensitivity to Metformin."

Metformin and radiation synergy

Metformin can be taken in the same amount that diabetics take every day, as opposed to the amount that patients would have to take of other drugs, making them unable to even get to clinical trials.

Tsakirdis' paper, published Wednesday through the British Journal of Cancer, states that Metformin inhibits the growth of cancer cells, and can even stop them from growing. By triggering molecular mechanisms that radiation also triggers, a "synergistic effect" is created.

Tsakirdis specializes in lung and prostate cancer, and says there is a possibility Metformin can be used for other types of cancer as well. 

More than 120 million people worldwide use the drug for diabetes, according to Tsakirdis, but not for cancer. However, it is currently in clinical trials for breast cancer.

Clinical trials

Lung cancer clinical trials are in the preparation stage, and Tsakirdis estimates about a year until they Metformin is available for human use for lung cancer.

"We were trying to find ways to sensitize lung cancer to radiotherapy," says Tsakirdis on how he realized Metformin may work for cancer. "While we were doing the work, we realized that radiotherapy is triggering mechanisms which are triggered by the drug."

There are a few different reasons as to why Tsakirdis investigated a link between Metformin and lung cancer.

Firstly, the fact that it seemed to modulate the same molecular mechanisms that radiotherapy does, meaning the combination of the two was a promising idea, according to Tsakirdis. Secondly, it is a well-tolerated drug in patients, with little to no side effects.

"The most exciting part of the work was the fact that the drug, in lung cancer specifically, worked in very low doses," says Tsakirdis. "That's what made this work even more interesting."

Quality and quanitity of life

Tsakirdis hopes lung cancer patients will be able to take Metformin to improve the quality and the length of life.

"It may reduce the need for other very toxic drugs, so we reduce the dose that we give of radiation or chemotherapy during the treatment," says Tsakirdis. "The future of the drug may actually improve the lives by preventing cancer from developing, or preventing it from coming back after the treatment has been completed."

"These days a lot of cancer patients will survive, but they suffer with the side effects of the treatment, and that's where the drugs that are well tolerated will make a difference."