A retrospective study of treatment outcomes in patients with carcinoma of unknown primary site and a colorectal cancer molecular profile.

BACKGROUND

Molecular tumor profiling is a new method of identifying the tissue of origin in patients with carcinoma of unknown primary (CUP) site. However the value of this information in improving treatment outcomes is undefined. We evaluated results of site-specific treatment in a group of patients with CUP in whom molecular profiling predicted a colorectal site of origin.

PATIENTS AND METHODS

Tissue of origin predictions by a 92-gene real-time polymerase chain reaction (RT-PCR) molecular profiling assay (CancerTYPE ID; bioTheranostics, Inc, San Diego, CA) from March 2008 to August 2009 were reviewed. One hundred twenty-five of 1544 patients (8%) assayed were predicted to have a colorectal tissue of origin with > 80% probability. Surveys were sent to the physicians of these 125 patients requesting deidentified patient information.

RESULTS

Information was provided for 42 of 125 patients (34%). Thirty-two patients received either first- or second-line therapy with colorectal cancer regimens; the overall response rate was 50%. Patients who received first-line empirical therapy for CUP had an overall response rate of 17%. The median survival of patients who received site-specific therapy for colorectal cancer was 27 months.

CONCLUSIONS

Patients predicted to have a colorectal site of origin by molecular tumor profiling had median survival when treated with site-specific regimens that was similar to survival in patients with known metastatic colon cancer. The median survival in this group was substantially better than the historical median survival for patients with CUP (range 8-11 months) when treated with empirical CUP regimens. Molecular tumor profiling seems to improve survival by allowing specific therapy in this patient subgroup; prospective trials are ongoing to confirm these observations.