Reclassifying cancers 'will improve treatment'

Cancers should no longer be categorised by where they are first formed in the body, but instead by their genomic and molecular makeup, a new study concludes.

In this way the researchers, writing in the journal Cell, say drugs used for the treatment of other conditions, such as rheumatoid arthritis, could also ultimately be repurposed to fight cancer.

Cancers have traditionally been classed and treated according to the part of the body from which they originate, such as the breasts or lungs.

But for this new study, the Pan-Cancer Atlas, scientists carried out analysis of 23 of the most common tumour types, and also 10 rare ones, to see which similarities and differences they had on both a genetic and cellular level. They found all 33 could be reclassified into 28 clusters that shared similar molecules.

One tumour type was found in 25 parts of the body, meaning it would traditionally be treated differently depending on which area it was found in, the study found.

But by reclassifying by genomic and molecular similarities medications for one type of cancer - such as of the bladder - should be used to treat another, like lung cancer.

They found that nearly two thirds of cancer clusters that shared key molecular similarities were found in more than one area of the body. They also found that common cancers, such as in the lung and breast, can be broken down into more than one cancer.

"Patients will have the best shot at successful treatment if their tumours can first be classified according to their genomic and molecular makeup," lead researcher Professor Christopher Benz, from the Buck Institute for Research on Ageing in California, told the BBC.

But he explained that it could take up to a decade for new treatments to become available because of the difficulty in getting drugs approved.

He called for oncology departments, which tend to focus on specific areas of the body, and drugs companies to work together to better improve care for patients.

"It's time to rewrite the textbooks on cancer, and it's time to break down the silos in clinical oncology that make it difficult for patients to take advantage of this paradigm shift in cancer classification," Professor Benz said.

Dr Justine Alford, from Cancer Research UK, said: "By revealing the molecular groups that cancers tend to fall into, this research opens up new possibilities for patients who would traditionally be treated based on where in the body their cancer is. Identifying patients most likely to benefit from a particular treatment could also help improve clinical trials."

"The real test now will be to put this knowledge into practice and find out if this way of treating patients helps save more lives," she added.