Researchers have identified proteins that could be involved in the earliest stages of cancer, potentially offering the chance to detect the disease's development more than seven years before it is diagnosed.
More than 600 proteins have been linked to 19 different types of cancer, including bowel, prostate and breast.
Some of them were found in a group of people whose blood was collected at least seven years before diagnosis.
Scientists hope the findings from the two Cancer Research UK-funded studies could help efforts to prevent cancer before it starts.
Prof Ruth Travis, senior molecular epidemiologist at Oxford Population Health and a senior author of both studies, said to be able to prevent cancer, we need to understand the factors driving the earliest stages of its development.
“These studies are important because they provide many new clues about the causes and biology of multiple cancers, including insights into what’s happening years before a cancer is diagnosed,” she said.
“We now have technology that can look at thousands of proteins across thousands of cancer cases, identifying which proteins have a role in the development of specific cancers, and which might have effects that are common to multiple cancer types.”
Dr Iain Foulkes, executive director of research and innovation at Cancer Research UK, said: “Preventing cancer means looking out for the earliest warning signs of the disease.
“That means intensive, painstaking research to find the molecular signals we should pay closest attention to.
“Discoveries from this research are the crucial first step towards offering preventative therapies which is the ultimate route for giving people longer, better lives, free from the fear of cancer.”
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In the first study, scientists analysed blood samples from UK Biobank taken from more than 44,000 people, including 4,900 who subsequently had a cancer diagnosis.
The team used proteomics – the study of proteins to help learn how cancer develops and spreads – to analyse a set of 1,463 proteins from a single sample of blood from each person.
They compared the proteins of people who were later diagnosed with cancer and others who were not, allowing them to identify differences and establish which were linked to cancer risk.
The scientists also identified 182 proteins that differed in the blood three years before a cancer diagnosis.
In the second study, the researchers looked at genetic data from more than 300,000 cancer cases to analyse which blood proteins were involved in cancer development and could be targeted by new treatments.
About 40 proteins in the blood were found to influence someone’s risk of getting nine different types of cancer: bladder, breast, endometrium, head and neck, lung, ovary, pancreas, kidney and malignant non-melanoma.
Although altering these proteins may increase or decrease the chances of someone developing cancer, in some cases it may lead to unintended side-effects, the findings showed.
The researchers emphasised that further studies are needed to find out the exact role the proteins play in cancer development.
It is also important to determine which are the most reliable ones to test for, what tests could be developed to detect the proteins in a clinic, and which drugs could target them, the scientists added.
A test called the Galleri test is undergoing trials in Britain's NHS, but it works by detecting tumour DNA circulating in the blood.
Researchers suggest the proteins they have discovered could be targets for cancer prevention.
Prevention and early detection are needed to keep improving cancer survival.
The findings were published in the Nature Communications journal.
