Useful DNA typing using AmpFlSTR Identifiler Kit for formaldehyde-fixed paraffin-embedded (FFPE) tissues in early gastric cancer patient with lymph node metastasis.

After distal gastrectomy in a patient with early gastric cancer, 27 regional lymph nodes around the stomach were evaluated for the existence of metastasis. There was a 0IIa+IIc type tumor 2.0 x1.5 cm in size in the gastric angle of the lesser curvature according to the Japanese Classification of Gastric Carcinoma (JCGC). Histologically, the lesion extended no deeper than the muscularis mucosae. The cancer stage was so early that no metastasis was expected to occur but a lymph node with metastasis was found in one lymph node along the common anterior hepatic artery (station No.8a). This histological type was a little different from that of a primary tumor. The doctor began to suspect that the lymph node with metastasis might have been from another patient by mistake. Therefore, DNA typing using the AmpFlSTR Identifiler kit was performed in formaldehyde-fixed paraffin-embedded (FFPE) tissues: 2 parts of gastric mucosa without cancer, one part of gastric mucosa with cancer, 4 lymph nodes without metastasis, and the lymph node station No.8a with metastasis. STR typing was successful in 6~14 STR loci and amelogenin gene, and the detected STR type was the same in all samples. Compared with the STR type using DNA from the patient's blood, the lymph node station No.8a was from the same patient. The lymph node with metastasis turned out to be not from another patient. Therefore, we suggest that DNA typing using the AmpFlSTR Identifiler Kit for FFPE samples is useful in such clinical cases.