Incidental Diagnosis of Pancreatic Cancer and Association with Improved Patient Outcomes: Assessing the Potential Clinical Use of Liquid Biopsy-Based Screening Tests.

[BACKGROUND] Poor outcomes in pancreatic ductal adenocarcinoma (PDAC) are associated with delayed diagnosis and early systemic spread of disease. The development of liquid biopsies for screening could help detect early-stage disease in asymptomatic patients. We aimed to evaluate the association between incidental diagnoses and outcomes and to assess the potential role of liquid biopsies.

[STUDY DESIGN] An institutional registry was used to identify patients undergoing resection for PDAC between 2010 and 2015. Patients were stratified on the basis of presenting symptoms, and outcomes were analyzed. Preoperatively collected plasma from these patients was analyzed using a multianalyte screening test based on circulating tumor DNA and proteins.

[RESULTS] Seventy-nine of 823 patients (9.6%) were diagnosed incidentally (asymptomatic at diagnosis). Incidental diagnosis was associated with type of surgery and absence of nodal disease and lymphovascular invasion (all p < 0.05). On multivariable analysis incidental diagnosis (hazard ratio [HR] 0.561, 95% CI 0.406 to 0.775, p < 0.001) was independently associated with improved overall survival (OS), whereas tumor size greater than 4 cm (HR 1.617, 95% CI 1.201 to 2.176, p = 0.002), nodal disease (HR 1.259, 95% CI 1.018 to 1.558, p = 0.034), perineural invasion (HR 1.338, 95% CI 1.030 to 1.739, p = 0.029), and positive margins (HR 1.302, 95% CI 1.058 to 1.602, p = 0.013) were associated with poorer OS. Asymptomatic patients had a significantly longer OS (median OS 38 vs 19 months, p < 0.001). The rate of multianalyte test positivity was 75% (6 of 8) in asymptomatic patients compared with 73% (59 of 81) in symptomatic patients (p = 0.895).

[CONCLUSIONS] Approximately 10% of patients with PDAC are diagnosed incidentally. In resected PDAC, incidental diagnosis is independently associated with improved OS. Multianalyte screening tests perform equally well in asymptomatic and symptomatic patients. These findings further reinforce the need to develop screening tools that increase the rate of diagnosis at an asymptomatic stage and improve survival.