Positron emission tomography combined with computed tomography for diagnosis of synchronous tumors

The hybrid method 18F-FDG PET/ CT has been proven as a method of choice in oncology for diagnostics, staging, restaging of the tumor and evaluation of the therapeutic effect. The aim of the study was to determine the value of 18F-FDG PET/ CT for detection of synchronous tumors and consequently the influence on the patients management.

The examinations were performed on Discovery, GE Healthcare PET/ CT using standard protocol. Among the patients, examined by 18F FDG  PET/ CT for one year (n = 1 408), unsuspected synchronous tumors were detected in 11 cases (0.8%).

Five pulmonary carcinomas, four head and neck squamous cell carcinomas (HNSCC), one ovarian carcinoma and one tumor of the sigma were detected as second malignancies. The histology verification was done in five cases (all HNSCC and one sigma carcinoma). In one patient with ovarian carcinoma, histology was obtained after surgery. In the rest of patients, no verification was undertaken because of the patients refusal and the advanced stage of the diseases, demanding systemic chemotherapy. Four patients (three with HNSCC and one with ovarian secondary malignancy) had favorable outcome during the nine  month  follow up.

The hybrid method PET/ CT, combining the metabolic and morphologic findings, can help detection of synchronous malignancies in a small percentage of cases, but with a positive influence on management of considerable part of such patients.