Caren van Roekel

62 Chapter 2 8.3. Other tumor types Radioembolization is also increasingly used for hepatic metastases of other primary tumors, such as intrahepatic cholangiocarcinoma, breast carcinoma, pancreatic adenocarcinoma, renal cell carcinoma and uveal melanoma. In all these tumor types, radioembolization shows promising results with limited toxicity (133-137). 9. FUTURE DIRECTIONS 9.1. Retreatment Radioembolization is usually performed as a mono-therapy (i.e. one shot), after failure of other therapeutic options. However, sometimes there is an indication for repeated radioembolization. Patients may have an impaired liver function after a previous radioembolization treatment, which raises questions regarding safety. Two studies have investigated the safety of repeated radioembolization. Lam et al. describe 8 patients that underwent repeated treatment, defined as multiple treatments to the same target volume. The second procedure was done with a reduced radioactivity dose. The interval between treatments was 203-968 days. After the second treatment, 3 patients had stable disease, 4 patients partial response and 1 patient complete response. After the second radioembolization procedure, two patients developed REILD and deceased shortly after treatment. The authors concluded that a higher administered activity per target volume increased the risk of REILD (138). Zarva et al. analyzed repeated radioembolization in 21 patients with HCC or hepatic metastases from different primary tumors. Sixteen patients received 3 lobar treatments, 4 patients received 4 lobar treatments and 1 patient received 5 lobar treatments. The interval between sessions was 4-6 weeks. The most frequent adverse events were ascites, elevation of bilirubin or liver enzymes and decrease of serum albumin levels. There were no grade IV or V toxicities. Median time to progression after the first treatment session was 3 months and median OS was 18 months (139). Despite the possible increased risk of REILD, repeated radioembolization may be a good option for patients with progressive disease after radioembolization.