Abstract
Gastric cancer ranks as the fourth most common cancer and the second most frequent cause of cancer death worldwide.1 The aetiology includes causes such as Helicobacter pylori infection (for distal gastric cancer but not for cardia cancer),2 dietary imbalance, smoking, and genetic factors.2,3 Estimation of the incidence of second primary cancers may provide valuable insight into the aetiology and shared risk factors with the initial cancer. However, as gastric cancer patients have poor survival,4 a study of second malignancies after primary gastric cancer may not be informative. Instead, we examined the occurrence of second gastric cancers following any first cancers, based on the nationwide Swedish Family Cancer Database. This database has been described in detail previously.5 Briefly, it was created by linking information from the Multigenerational Register, censuses, Cancer Registry, and death …