Tumor genomic profiling to determine tissue origin of cancers of unknown primary: a single institute experience with its utility and impact on patient management

Abstract

Tumor genomic profiling represents a promising tool in diagnosis and management of cancer of unknown primary. We report our experience on the impact of genomic profiling in elucidating primary tumor site, correlation with pathologic findings and patient management. Tissue or cytology specimens from 22 cancers of unknown primary were referred for genomic profiling. Reports were available to review in 18 cases; 3 samples were inadequate for analysis. of the remaining 15 cases, primary tumor site was suggested in 12 cases (80%), whereas it remained indeterminate in 3 (20%). of the 12 cases, molecular profiling was concordant with light microscopy findings in 3 patients, whereas in 2 cases molecular testing identified a sarcoma, contradicting light microscopy and immunohistochemistry findings. The suggested primary was confirmed by additional immunohistochemistry in 1 case and by endoscopic biopsy in another. In 5 cases, follow-up biopsy or additional testing were not considered necessary for patient management. Three patients received palliative care and 12 received various chemotherapy regimens. Five patients died within a year, whereas 9 were alive more than a year after diagnosis, 3 of who were alive >3 years after diagnosis. In conclusion, genomic profiling helped confirm the original diagnosis and suggested primary sites in two third of our cases. Although many patients may be at a disease stage too advanced to withstand further investigations or underg aggressive therapy, molecular testing improves diagnostic accuracy and may thus assist in selection of the most appropriate therapy.