Background: Familial clustering of upper gastrointestinal (UGI) cancers and the significance of family history has been addressed previously. We aimed to elucidate the familial risk based on the specified tumor location and histology. Method: In the Swedish Family-Cancer Database, we determined the familial risk of UGI cancer patients diagnosed (1958–2015) with esophageal and gastric cancer by tumor location using standardized incidence ratios (SIRs). Results: Risk of esophageal cancer in first-degree relatives (FDRs) of patients with esophageal cancer increased 2.4-fold (SIR 95% CI 2.0–2.8), whereas risk of esophageal cancer in cases with family history of cancer in the middle third of the esophagus increased 3.4-fold (SIR 95% CI 2.1–5.1). Risk of gastric cancer in FDRs increased 1.6-fold (SIR 95% CI 1.5–1.7), occurrence of concordant subsite gastric cancer in the antrum, body, and cardia was 5.5-fold (SIR 95% CI 2.4–11), 4.6-fold (SIR 95% CI 2.6–7.4), and 1.7-fold (SIR 95% CI 1.1–2.5), respectively. Familial risk of concordant histological subtype in esophageal cancer was 4.1-fold for squamous cell carcinoma (SIR 95% CI 3.2–5.2) and 3.6-fold for adenocarcinoma (SIR 95% CI 2.5–5.1). The risk of concordant gastric adenocarcinoma was 1.6-fold for one affected FDR (SIR 95% CI 1.5–1.7), 6.1-fold for two FDRs (SIR 95% CI 4.4–8.4), and 8.6-fold among twins (SIR 95% CI 2.3–22). Conclusion: Family history of cancer in the lower third of the esophagus and stomach cancer in specific locations such as the antrum, body, and cardia can be considered as important predictive evidence for cancer in the same location in relatives. Our findings might guide endoscopy-based surveillance by introducing subgroups of populations with a higher risk for UGI cancer with particular attention to concordance of location of lesions, which could be a reasonable strategy for early detection, and thus help save more lives.
