A cross-disciplinary team of pathologists, physicians and scientists at University Health Network have defined a new way to classify the most common type of pancreatic cancer. The new classification system better reflects clinical outcomes than current methods.
The focus of the study was a cancer known as pancreatic ductal adenocarcinoma (PDAC), which is one of the most lethal of all cancers, with a five-year survival rate of less than 10 per cent.
“Although histological evaluation—looking at the tissue under the microscope—has served as the standard method of diagnosing and classifying PDAC, molecular analysis have since revealed two molecular subtypes that can stratify patients based on clinical outcomes.” says Dr. Sangeetha Kalimuthu, the lead author of the study, and gastrointestinal pathologist at the University Health Network.
She teamed up with Dr. Runjan Chetty, from UHN’s Laboratory Medicine Program, and Dr. Steven Gallinger, from UHN’s Hepatobiliary/Pancreatic Surgical Oncology Program, to explore whether this new molecular information could be used to revise and improve how pathologists classify these cancers.
The group assessed over 800 histological tumour tissue slides from 86 patients with PDAC. The slides were linked to their respective molecular profiles and patient outcome data. Combined, the data enabled the team to develop a revised two-tiered pattern-based classification system that provides more information about the cancer versus the current three-tiered system.
“The current three-tiered system—which grades tumours as well, moderate or poor—is limited in that the majority of tumours fall within the moderate category. This provides little insight when deciding on treatment plans. Our two-tier system overcomes this issue, while serving as a better predictor of outcomes,” says Dr. Chetty, senior author of the study.
This new classification system provides pathologists with a quick and affordable way to better classify PDACs and to identify the most aggressive tumours. Of the findings, Dr. Steve Gallinger a co-author in the research, says, “This study is an elegant demonstration of the potential of personalized medicine, with the promise of improved outcomes for our patients."
N Kalimuthu S, Wilson GW, Grant RC, Seto M, O'Kane G, Vajpeyi R, Notta F, Gallinger S, Chetty R. Morphological classification of pancreatic ductal adenocarcinoma that predicts molecular subtypes and correlates with clinical outcome. Gut. 2019 Jun 14. pii: gutjnl-2019-318217. doi: 10.1136/gutjnl-2019-318217.
Dr. Sangeetha N Kalimuthu, pictured in the Surgical Pathology Laboratory at Toronto General Hospital, is the first author of the study.