Metastasis is the leading cause of death amongst patients, diagnosed with uveal melanoma (UM).1-3 Depending on, the AJCC cT category and method of detection, overall, 1.9% (cT1–cT4) and up to 20% of select cT4 patients, have demonstrable metastatic disease at the time of ocular, diagnosis.4,5 However, even after local treatment, a, tumor-size-based risk of metastasis (mean 50%, range, 10%–90%) exists within 10 years (Fig. 27-1).4,6-8 This is, attributed to the slow growth of previously seeded metastatic, tumor cells, which are undetectable to all existing, screening methods. It is widely accepted that subclinical, metastases remain occult for years until they grow, to a certain size to become radiologically detectable.9,10, Therefore, multiple research studies have focused on, extending life for patients with metastatic UM utilizing, early detection as to allow time for palliative and sometimes, curative treatment.2,9,11, The hunt for metastatic UM starts at initial diagnostic, staging. Large multicenter international studies have, revealed that clinical characteristics (e.g., ciliary body, origin, presence of extrascleral extension, greater tumor, thickness, and largest basal diameter) are associated with, a greater risk for metastases at initial presentation.2,4-6,9, The most common metastatic sites at presentation are, the liver (91%), lung (16%), bone (9%), brain (6%), skin, (4%), and others (5%).4,5,7,12 In that multiorgan disease has, been identified in over 80% of patients with metastatic, disease, this data supports multiorgan screening (Figs., 27-2 and 27-3).4,5,7,9,12 In addition, multiple centers have, reported that UM patients are at risk for second nonocular, primary cancers, suggesting a genetic predisposition, to cancer (Fig. 27-2)., Genetic studies support mutations in BAP1, GNAQ,, GNA11, LZTS1 (8p22), DDEF1 (8q24.21), PTP4A3, (8q24.3), TCEB1 (8q21.11), EIF1AX, and SF3B1 (see, Abbreviations section) as predisposing factors for UM, metastasis (see Chapter 26).2,13 Structurally, monosomy, 3, 1p loss, 1q gain, 6q loss, 6p gain, 8p loss, and 8q gain, are common chromosomal abnormalities in UM.14-19, The data suggests that both AJCC cT-category, genetic, information, and the patient’s health status may be selectively, employed to modify the intensity or periodicity, of post-treatment systemic surveillance (Mind map, 27-1).4,6,9,14,18-22, However, to date, no consensus guidelines have been, established for methods of diagnosis, surveillance, or, treatment for metastatic UM. In 1985, the COMS methods, for metastatic surveillance included a combination of, physical examination for hepatomegaly, enlarged lymph, nodes, and subcutaneous nodules, as well as ancillary, chest X-rays (CXR) and liver function tests (LFT). These, methods were specific but not sensitive, thus typically, diagnosing only late-stage disease.20,21, In the modern era, a shift toward radiographic systemic, screening has allowed metastatic screening to, be more sensitive and specific for early asymptomatic, metastasis.5,23 Today, we rely more heavily on PET/CT,, abdominal CT or MRI, CXR, or abdominal-hepatic, ultrasound (USG).4,5,23-26 Of these radiographic methods,, only whole-body, PET/CT offers radiographic screening, that can reveal both hepatic and extrahepatic UM, metastasis.4,5 PET/CT has also been found to reveal second, nonocular primary cancers and help differentiate, melanoma from uveal metastasis in this population.5,25,27, Clearly, hematologic surveys now play a less prominent, role. In general, current options for surveillance of metastatic, UM include physical examination, hematologic, screening, and radiographic imaging (Table 27-1).