What happened, in summary

A man underwent living kidney donation and was later treated for early gastric cancer at age 71. The cancer was removed successfully by endoscopic submucosal dissection, allowing treatment through an endoscope rather than open stomach surgery. Endoscopic removal completed his gastric cancer treatment.

Eight years after the gastric procedure, when he was about 80, routine follow-up detected significant protein in his urine. He had donated a kidney to his daughter 9 years earlier and had maintained stable kidney function since donation. A kidney biopsy showed NELL-1-positive membranous nephropathy. Because this kidney condition can sometimes be associated with cancer, he underwent a broad evaluation that included tumor markers, upper and lower gastrointestinal endoscopy, and imaging. The assessment found no recurrence of the gastric cancer and no other malignancy. The original stomach-cancer tissue was no longer available, so NELL-1 staining could not be performed on the tumor and a direct connection between the earlier cancer and the later kidney disease could not be established.

The kidney condition was managed conservatively with losartan 25 mg daily and dietary changes. Proteinuria gradually declined to 0.13 g/gCr over 3 years, while kidney function remained stable. From the cancer perspective, the important long-term finding was the absence of recurrent gastric cancer 8 years after endoscopic treatment.