Association of Age With Tumor Grade in Patients With Digestive Tumors: A Study Based on US SEER Registry

Abstract

Background: Previous studies have not demonstrated an independent association of age and tumor grade. In this study, we aimed to explore the relationship between age and tumor grade (differentiation) in patients with digestive tumors.Methods: Surveillance, Epidemiology and End Results (SEER) 18 registry database for 1973 through 2015 was retrieved for the present study. Both piecewise and non-piecewise linear regression model were utilized to examine the relationship between age and tumor grade. Results: The present study included a total of 938,145 patients with 13 types of primary malignancies of the digestive system. In non-piecewise regression analyses, older age was associated with higher tumor grades in patients with esophageal squamous cell carcinoma (P < 0.0001) and anal squamous cell carcinoma (P < 0.0001). In contrast, older age was related to lower tumor grades in patients with esophageal adenocarcinoma (P = 0.0177), gastric adenocarcinoma (P < 0.0001), pancreatic adenocarcinoma (P < 0.0001) and rectal adenocarcinoma (P < 0.0001). In piecewise regression analyses, positive associations of age and tumor grade were only observed in specific age groups in some types of tumor, e.g., anal adenocarcinoma (> 66 years), gallbladder adenocarcinoma (> 49 years), pancreatic adenocarcinoma (> 56 years), hepatocellular carcinoma (35-90 years), rectal adenocarcinoma (<59 years in White; < 52 years in Non-White) and anal squamous cell carcinoma (<51 years in White; < 58 years in Non-White). Patients with well-differentiated tumors had better long-term prognoses compared to those with poorly-differentiated tumors (all P < 0.05). Conclusion: The patterns of relationship between age and tumor grade were different in patients with different types of digestive tumor, which may be a reflection of the distinct molecular subtypes of these tumors.