Pancreatic cancer is aggressive, with 60–80% of patients in advanced stages with distant metastasis at presentation. The number of cases diagnosed in the advanced stages will increase with the recent American Joint Committee on Cancer (AJCC) 8th edition of the staging criteria. These new criteria are expected to allow finer stratification of cancer stages based on tumour size and lymph node involvement, increasing the prognostic accuracy in the resected cancer. GlobalData epidemiologists expect 25% of all stage Ia–IIb cases (localised) diagnosed by AJCC 7th criteria will be reclassified to stage III (advanced) based on AJCC 8th criteria in the US.
Currently, more than half of new pancreatic cancer cases are diagnosed in stage IV, when it has metastasised. Under the AJCC 8th criteria, the proportion of cases in the US in stage III will increase from 10% to 20% while stage Ia–IIb will decrease from 40% to 30% (Figure 1). The overall proportion of cases in 2020 diagnosed in advanced stages (III and IV) was over 70%.
Pancreatic cancer is notoriously hard to diagnose early because it tends to remain asymptomatic or has nonspecific symptoms. To improve the survival rate, it needs to be diagnosed earlier and the progression of the disease needs to be assessed carefully. The advantage of AJCC 8th criteria is that the finer stratification of stages based on tumour and lymph node involvement will help guide whether the cancer is operable and the prognosis of the resected cancer.
The US national cancer registry has not yet provided the data on staging based on AJCC 8th criteria. A number of studies that have modelled the existing US registry data indicate that diagnostic and prognostic accuracy is improved by differentiating localised and advanced stages. It is unclear whether this improves the overall survival rate. This needs to be explored in further studies. It is also important that the national cancer registry provides the updated staging data soon, which will help in the comparison of stages.