A cancerous cell
A cancerous cell

Scientists have discovered a mechanism that causes an aggressive from of lung cancer to re-grow despite being treated with chemotherapy.

The researchers, conducted by scientists at the Monash University in Melbourne with colleagues in the United States, are hoping that the discovery could have major implications for the future treatment of millions of cancer patients.

The researchers focused on a fast-spreading small cell lung cancer, which has a five-year survival rate of only five per cent.

While many current cancer treatments and trials focus on shrinking existing tumours, this research had a different approach, said Professor Neil Watkins, of the Monash Institute of Medical Research (MIMR).

"Some aggressive types of cancer respond very well to chemotherapy, but then the real challenge is to stop the tumour coming back. That's what we investigated," said Professor Watkins.

Many lung cancer patients respond well to chemotherapy and go into remission. However, in many cases the cancer returns to quickly take the life of the patient.

Scientists have been confused as to why they cannot detect any trace of cancerous cells after chemotherapy treatment.

Professor Watkins said that using a drug to block a type of protein known as 'Hedgehog' could form the basis of new small cell lung cancer treatment (SCLC) treatments.

"This discovery gives us important clues for designing new treatment approaches. By using drugs to inhibit the Hedgehog signalling, we should be able to increase the effectiveness of chemotherapy and reduce the risk of cancer relapse," said Professor Watkins.

"We have gone a long way to showing how tumour cells regenerate and that's been a mystery for a long time," he said.

"What we found was that ... the hedgehog is very important when the cells are depleted down to a tiny population and are asked to regenerate the tumour.

"If you use drug that blocks the hedgehog signalling (for the cancer cells to regenerate) you can prevent small cell lung cancer cells from regenerating after chemotherapy," said Professor Watkins.

"This discovery gives us important clues for designing new treatment approaches. By using drugs to inhibit the Hedgehog signalling, we should be able to increase the effectiveness of chemotherapy and reduce the risk of cancer relapse," said Professor Watkins.

Prof Watkins said he hoped drug companies would use the research as the basis to carry out clinical trials in cancer patients.

"If you wanted to test what we found in people you would need to get patients who have had a complete remission following chemotherapy and then start them on the treatment to see if it prevented it from coming back," he said.

"But you wouldn't have any immediate way of measuring if the drug worked. You would have to wait 12 months (to see if the cancer regenerated)."

The research was published on Monday in the journal Nature Medicine.