What happened, in summary

A 28-year-old Vietnamese man sought care after 5 months of epigastric pain, weight loss and painful swollen lymph nodes in his neck. Gastroscopy found an ulcer larger than 3 cm in the stomach. Biopsy showed Stage IV diffuse-type gastric cancer with signet-ring cells and no Helicobacter pylori infection.

Because of financial constraints, he declined further staging tests such as lymph-node biopsy, CT and PET/CT, and he did not proceed with anticancer treatment. His health deteriorated rapidly, and he died 4 months after diagnosis.

Because the cancer developed at such a young age and had diffuse, signet-ring features, genetic testing was performed. Blood testing identified a novel CDH1 nonsense mutation, c.639G>A (p.W213*), which creates an early stop signal in the gene. Tumor tissue also showed decreased E-cadherin expression. The same CDH1 alteration was found in his father and one uncle, even though neither had gastric cancer at the time of testing. His father’s gastroscopy showed gastritis, intestinal metaplasia and low-grade dysplasia but no cancer.

The finding supported hereditary diffuse gastric cancer despite the absence of a known family history of the disease and prompted testing and surveillance discussions for relatives.