- Scientists want different types of cancer to be classified based on molecular composition
Naming cancers after body parts hampers treatment and ‘must change’, experts have argued.
A group of scientists have called for different forms of the disease to be classified based on molecular composition, rather than the part of the body where the disease originates.
Over the past century, the main approaches to treating people with cancer have focused on the site in the body where the tumor first developed.
But classifying cancers based on their organ of origin hinders access to potentially life-saving drugs, scientists say.
A group of scientists have called for different forms of the disease to be classified based on molecular composition, rather than the part of the body where the disease originates. stock
Instead, cataloging cancers by the biological mechanisms that cause them could lead to more personalized treatment – and help patients better understand their disease.
A group of experts from Gustave Roussy – a cancer treatment center in France – made their arguments in a commentary piece published in the journal Nature.
In it, they give the example of a cancer drug called nivolumab, which can improve outcomes for patients.
In studies – involving people with different ‘types’ of cancer – the drug has been shown to shrink some people’s tumors by more than 30 percent, but has little or no effect on others’ tumors.
Researchers found that the main determinant of the drug’s effectiveness was whether the tumors expressed high levels of a certain protein.
But because of the way cancer is classified (breast, kidney, lung, etc.), the team had to conduct further clinical trials for each disease type, rather than a study that focused solely on tumors that highly expressed this protein.
As a result, millions of people with tumors expressing high levels of this protein were unable to access relevant drugs for about a decade because no trials had yet been conducted for their type of cancer, the experts wrote.
And they argued that a similar story has played out with most drugs tested in clinical trials over the past decade.
They wrote: ‘Metastatic cancers – cancers that have spread beyond the organ where they originated – account for approximately 67-90 percent of cancer deaths and are almost always treated systemically, that is, with drugs given in the enter the bloodstream.
‘This attachment to classifying cancer – and tackling it – based on the organ in which it originated slows progress in multiple ways.
‘To improve treatments for people with metastatic cancer, the community urgently needs to move from using organ-based cancer classifications to using molecular classifications.
‘This requires radical changes in the way medical oncology is structured, delivered and taught.’
They said that if patients are told about the biological mechanisms driving their cancer, it could help them better understand the reasons for treatment.
“In the coming years and decades, numerous layers of information could be incorporated into comprehensive cancer characterizations unique to each patient,” she added.
‘This includes the organ of origin of the cancer, which sometimes remains an important factor in deciding which treatment to try, the number and size of tumors and their aggressiveness, as measured by the expression levels of certain genes.
‘Among other potentially useful information is genetic analysis of a person’s germline DNA, which can provide information about their sensitivity to certain drugs or their potential for harmful side effects; and their general health, as monitored by the level of fatigue, weight loss and so on.
‘Classifying cancers based on their molecular characteristics would accelerate millions of people’s access to effective treatments.
‘It is also the first step towards precision oncology and a deeper biological understanding of how cancer works.’