Major study reveals new ways to classify cancer

A US-led initiative to map the molecular similarities and differences of thousands of tumours has revealed new ways to classify cancer.

A US-led initiative to map the molecular similarities and differences of thousands of tumours has revealed new ways to classify cancer.

Called the Pan-Cancer Initiative, the project reinforces recent research showing that cancers starting in the same part of the body can be distinct at a molecular level and so potentially respond in different ways to therapy. Conversely, tumours in different parts of the body can share genetic changes that might make them susceptible to same types of treatment.

The research could be an important step towards more precise cancer treatment that is tailored to the molecular characteristics of an individual patient’s disease.

The Pan-Cancer Initiative is part of The Cancer Genome Atlas (TCGC) project, which is led by the National Cancer Institute and the National Human Genome Research Institute in America. TCGA is part of the International Cancer Genome Consortium (ICGC) – the globally coordinated effort to characterise thousands of tumours, of which Cancer Research is a key member.

Professor Josh Stuart from the University of California. He helped organise the Pan-Cancer Initiative and is lead author of a commentary in Nature Genetics giving an overview of the project and its initial findings.

“For years we’ve been looking at one tumour type at a time, but there are patterns you can only spot by making connections across different tissues and tumour types. Finding these similarities across tissues can have important implications for treatment,” Stuart said.

For example, the research found that some types of bladder cancer share molecular characteristics with certain lung and head-and-neck cancers.

“This could allow oncologists to apply all they know about treating head-and-neck squamous cell tumours to the ten percent of bladder cancers that have the same characteristics,” Professor Stuart said.

Professor Rebecca Fitzgerald, a Cancer Research UK scientist based at the university of Cambridge, said the work was “fascinating”.

“It suggests a departure from the way we distinguish between different cancers – not by where they appear in the body but by the molecular changes they share. It also reveals a number of similarities and differences between certain cancer types, which might help us to apply existing treatments in new ways,” she added.

The research also shows that the location of a tumour is nevertheless important, and produces a ‘dominant signal’ that groups tumours mostly according to their tissue of origin.

And the statistical power gained by combining all of the data available from different tumour types has helped the researchers to see new patterns that smaller studies have missed.

“In ovarian cancer, for example, we were able to identify mutations that correlate with the response to treatment, but only by using data from other types of cancer,” Professor Stuart said.

TCGA is generating comprehensive maps of the key molecular changes in 20 major types of cancer. The Pan-Cancer Initiative has analysed the first 12 tumour types profiled by TCGA.

Professor Stuart says that the new findings, reported in 18 forthcoming papers including the four published in Nature Genetics, could lead to fresh ways of categorising tumours in the future.

One goal from such new classifications is to identify tell-tale molecular signatures – or ‘biomarkers’ – that can be used across a range of tumour types to indicate which therapies are likely to be most effective. The studies could also point towards new treatment targets.

“These initial papers are just the first step,” Professor Stuart said.

Cancer Research UK is leading similar projects investigating prostate and oesophageal cancer – tumours that were not looked at in the US studies – which are being funded through the charity’s Catalyst Club and are part of the ICGC.

Professor Fitzgerald, said: “These projects, alongside the work of our global colleagues, are helping us to develop more sophisticated ways to diagnose and treat cancer.”

Copyright Press Association 2013