Screening for a sex-specific panel of 10 proteins can pick up 18 different early stage cancers, research shows. 

New findings could kick-start a new generation of screening tests for early detection of the disease, say researchers.

Cancer accounts for 1 in every 6 deaths around the globe, with nearly 60 per cent of these deaths caused by cancers for which no screening test exists.

Even existing screening tests have considerable drawbacks, including invasiveness, expense, and low levels of accuracy for early stage disease, they add.

Specific blood proteins could be used for early detection and ongoing monitoring, but the currently available options lack sensitivity (accuracy of picking up those with cancer) and specificity (accuracy of excluding those without cancer), say the researchers.

To explore the potential use of plasma proteins, including those that are currently barely detectable, researchers collected plasma samples from 440 people diagnosed with 18 different types of cancer before treatment, and from 44 healthy blood donors.

They then measured more than 3,000 proteins strongly associated with cancer chemical pathways in each sample, using a technology deploying antibodies and a statistical algorithm in a 2-step process.

The first step involved detecting the biological signature of any cancer, and the second step involved identifying the tissue of origin and cancer subtypes - small cell and non-small cell cancers of the lung, for example.

Through a process of elimination, a panel of 10 sex specific proteins emerged that were differentially expressed among the plasma samples from cancer patients and healthy people.

The fact that these protein signatures differed significantly between men and women suggests that they are most likely sex-specific for all cancers, say the researchers.

By themselves, each individual protein was only moderately accurate at picking up early stage disease, but when combined with the other proteins in a panel they were highly accurate.

These proteins were able to pick up stage I-III disease and all types of cancer, but were particularly effective at picking up early stage disease.

They identified 93 per cent of stage 1 cancers among the men and 84 per cent of stage 1 cancers among the women, with 99 per cent specificity and 90 per cent sensitivity in the men and 85 per cent sensitivity and 99 per cent specificity in the women.

A panel of 150 proteins were able to identify the tissue of origin of most cancers in more than 80 per cent of cases in both men and women. 

Analysis of the plasma protein amounts showed that almost all of them were present at very low levels, highlighting the importance of low-level proteins to pick up pre-cancerous and early stage disease before a tumour has yet to have any substantial systemic impact, say the researchers.

“Our new generation protein-based plasma test has shown high sensitivity in detecting a variety of early stage tumours in asymptomatic patients, making it a strong candidate for use as a population-wide screening tool that is not currently achievable with existing tests or techniques,” they say. 

More details are accessible here.