PIK3CA Mutations in Small Bowel Adenocarcinoma

Abstract

Aims and Background

PIK3CA mutations involving exons 9 and 20 are among the most common aberrations seen in human malignancies. The identification of PIK3CA mutations in small bowel adenocarcinoma (SBA) is sparse. There is some evidence that tumors with this mutation may be a good target for inhibitors of the PI3K pathway.

Case report

We report an exon 9 (G1624A: E542K) hot spot mutation in a 69-year-old man with sporadic jejunal cancer (T3, NI). A systemic search was made for other reports using Medline/Embase along with Sangers Institute Cancer Genome Project database. We analyzed and describe this mutation in these patients, including one of ours.

Results and Conclusion

A total of 8 tumor samples with confirmed somatic mutations out of a total of 86 samples were noted: rate 9.3% (95% confidence interval 4.5% to 17.5%). Overall, PIK3CA mutations were more common in duodenum (62.5%) and located most commonly on exon 9. The significance of PIK3CA mutation in SBA is unclear. Further studies on mutation analysis in larger cohorts with SBA are in order to identify and confirm relationships between these mutations and various clinical and pathologic variables such as age, lymph node status, distant metastasis, stage, and progression-free survival and association with other gene mutations.