MAR 26, 2012
Ocular Pathology/Oncology
This large retrospective case series reports on the use of combined whole-body positron emission tomography/computed tomography (PET/CT) screening for metastasis at the time of diagnosis of primary uveal melanoma. The use of this technology improved the yield of detecting metastases from uveal melanomas. A positive correlation was found between patients’ American Joint Committee on Cancer–International Union Against Cancer (AJCC-UICC) T-stage and the presence of metastatic disease.
This study also revealed a 3 percent incidence of synchronous nonocular primary cancers, suggesting an increased risk for cancer among patients with uveal melanoma. The results also suggest that PET/CT imaging has value for initial screening of patients diagnosed with choroidal melanoma.
The study included 333 consecutive patients diagnosed with uveal melanoma since August 2003 and examined with whole-body screening for metastatic disease with PET/CT. They also underwent liver function tests and physical examination. Abnormal findings prompted further biopsies, blood tests, imaging or clinical evaluations for confirmation.
Using the AJCC tumor, node, metastasis (TNM) seventh edition criteria, 104 tumors were classified T1 (31 percent), 162 T2 (49 percent), 37 T3 (11 percent) and 30 T4 (9 percent). Seven of 333 (2.1 percent) patients had metastatic melanoma. One tumor was a T3 and six were T4. Thus, 3 percent of T3 and 20 percent of T4 melanomas were found to have metastases at the time of initial diagnosis. Ten patients (3.3 percent) had synchronous second cancers and 28 (8.4 percent) concurrent benign lesions. The most common metastatic sites were liver (7/7) and bone (2/7).
These results suggest that PET/CT improves the yield of detecting both extrahepatic metastases, especially from tumors defined as AJCC-T4, and synchronous primary cancers, irrespective of the size of the uveal melanoma. PET/CT demonstrated high sensitivity and positive predictive values with respect to liver metastases, indicating an overall better performance than conventional screening procedures.
Although uveal melanoma remains the leading cause of death among patients diagnosed with this cancer, the study’s authors say that the potential benefit of detecting second cancers early with PET/CT should not be downplayed.