What happened, in summary

A Japanese man was diagnosed at age 53 with Stage IV poorly differentiated gastric adenocarcinoma involving distant lymph nodes. His first treatment was 8 cycles of S-1 plus cisplatin, followed by 3 cycles of S-1. He then received 7 cycles of nab-paclitaxel plus ramucirumab and later nivolumab. When the cancer progressed, additional treatment included irinotecan, trifluridine/tipiracil, and capecitabine plus oxaliplatin.

At age 57, 3 years 4 months after diagnosis, a gastric biopsy and paired blood sample were sent for tumor genomic profiling. A pathogenic TP53 variant appeared in both samples, raising concern for an inherited or mosaic cancer-predisposition finding, especially because several relatives had developed cancer later in life.

Follow-up testing compared blood, cheek-swab and fingernail DNA. The TP53 variant was found in blood and cheek cells but not in fingernails. The tumor specimen also contained many blood-derived cells, supporting clonal hematopoiesis rather than a germline TP53 mutation. He and two of his children received genetic counseling, and the family was reassured that the finding was unlikely to represent inherited Li-Fraumeni syndrome. Regular blood-count monitoring was recommended.