Duration of Reduced CA19-9 Levels Is a Better Prognostic Factor Than Its Rate of Reduction for Unresectable Locally Advanced Pancreatic Cancer

SIMPLE SUMMARY: Upon diagnosis, about 35% of patients have initially unresectable locally advanced pancreatic cancer. The prognosis of these patients is still poor. Chemotherapy alone has been generally accepted as a standard therapeutic approach. However, clinical decision-making processes have not been established for aggressive treatments such as surgery and chemoradiotherapy in patients with a response and stable case of initially unresectable locally advanced pancreatic cancer. In the current study, we evaluated the reduction rate and duration of carbohydrate antigen (CA) 19-9 within 6 months as long-term survival. Cases of over 44% CA 19-9 reduction only one month from the baseline after treatment were not significantly associated with overall survival. On the other hand, more than 3 months of over 44% CA 19-9 reduction was significantly associated with prognosis, which is the same as the occurrence of distant metastasis. Multidisciplinary treatment focus on local treatment is expected in these selected patients. ABSTRACT: A decrease in carbohydrate antigen (CA) 19-9 levels has been proposed as a prognostic marker for survival and recurrence in patients with pancreatic cancer. We evaluated the association between duration of reduced CA 19-9 levels during 6 months after treatment and long-term survival for 79 patients with unresectable locally advanced pancreatic cancer (LAPC). We calculated the differences between pretreatment and monthly CA19-9 levels. We categorized 71 patients with decreases in CA19-9 levels into three groups based on the duration of these reduced levels (>2, >3, and >4 months). The cut-off level for long-term (more than 2 years) survival was identified as a 44% reduction from the baseline, using a ROC curve. A reduction duration >2 months was not associated with overall survival (p = 0.1), while >3 months was significantly associated with survival (p =.04). In multivariate analysis, a reduction duration >3 months predicted a good long-term prognosis (odds ratio = 5.75; 95% confidence interval = 1.47–22.36; p < 0.01). In patients with unresectable LAPC, the duration of reduced CA19-9 levels for more than 3 months, rather than the rate of reduction in CA19-9 levels, during 6 months after treatment was significantly associated with good prognosis.