For cancers that are difficult to diagnose and are frequently diagnosed at an advanced stage, a blood test that can be done in the community in mildly symptomatic or asymptomatic individuals would present an attractive option for detecting cancers earlier. One such cancer is pancreatic cancer, which has a median survival of only 4-6 months, in part due to late diagnoses.
The design of a new cancer blood test requires the identification of molecules in the blood that are specific for people with a current cancer or at risk of a future cancer but are not found in people without cancer. Some potential biomarkers have previously been identified for pancreatic cancer, but these are not able to discriminate sufficiently between cancer and non-cancer for them to be applied in the clinic, especially in asymptomatic people.
Dr Christiana Kartsonaki, a senior scientist at the MRC Population Health Research Unit in Oxford Population Health, has used data from the China Kadoorie Biobank to search for protein biomarkers in the blood that are associated with a subsequent diagnosis of pancreatic cancer. The China Kadoorie Biobank comprises over 500,000 Chinese adults, with blood samples collected at baseline. During 9 years of follow-up, 700 individuals went on to develop pancreatic cancer.
The levels of 92 different proteins were compared between the group that developed pancreatic cancer and a group of 700 individuals that did not develop pancreatic cancer. 15 proteins were associated with pancreatic cancer risk and, for most of these, the risk increased with a higher level of the protein. Some of these associations varied with time prior to a diagnosis, meaning it may be possible to use these to predict short-term risk. Adding these proteins to a risk prediction model with established risk factors for pancreatic cancer slightly increased the discriminatory ability of the model, especially in the short term.
Earlier detection, even if only by a few months, could benefit patients and may allow the use of treatments such as surgery. The protein biomarkers we have identified here now need to be replicated in other studies. Future studies could also look at whether these proteins can be used to monitor high-risk individuals over time or used as part of diagnostic testing in symptomatic individuals. - Dr Christiana Kartsonaki, lead author of the research.