(1) Background: Recent studies have reported elevated risks of multiple cancers in the World Trade Center (WTC) affected community members (also called WTC “Survivors”). The large variety of WTC-cancers created a need to develop a comprehensive cancer database. This paper describes the development of a pan-cancer database at the WTC Environmental Health Center (EHC) Data Center. (2) Methods: A new REDCap-based pan-cancer database was created using the pathology reports and available biomarker data of confirmed cancer cases after review by a cancer epidemiologist, a pathologist, physicians and biostatisticians. (3) Results: The WTC EHC pan-cancer database contains cancer characteristics and emerging biomarker information for cancers of individuals enrolled in the WTC EHC and diagnosed after 11 September 2001 and up to 31 December 2019 obtained from WTC EHC clinical records, pathological reports and state cancer registries. As of 31 December 2019, the database included 3440 cancer cases with cancer characteristics and biomarker information. (4) Conclusions: This evolving database represents an important resource for the scientific community facilitating future research about the etiology, heterogeneity, characteristics and outcomes of cancers and comorbid mental health conditions, cancer economics and gene–environment interaction in the unique population of WTC survivors.