Case histories in unresectable liver-dominant metastatic colorectal cancer

The most common cause of death from advanced colorectal cancer is disease progression of hepatic metastases. Selective internal radiation therapy (SIRT) is a technique for administering resin or glass microspheres that contain yttrium-90 to unresectable primary or secondary hepatic malignancies via the liver’s arterial supply in a single procedure. Chemoradiation studies suggest that the greatest clinical benefit from yttrium-90 microsphere SIRT is gained by rational combination with radiosensitizing systemic chemotherapy (Figure 1) [1,2] in order to achieve both temporal modulation and biological cooperation between these treatment modalities. There is an established evidence base for rational combinations of SIRT with fluoropyrimidine-, oxaliplatinand irinotecan-based regimes, based on radiobiological principles [3–5]. In particular, patients who cannot tolerate infusional 5-fluorouracil (5-FU) or capecitabine who have liver-only or liver-dominant metastatic disease should be considered for SIRT [6,7]. Detailed histological analysis of the liver tissue in patients resected 4–9 months after chemotherapy and SIRT shows that a complete pathological response can be achieved. Furthermore, fibrosis, ectatic vessels and vascular changes were predominantly observed (i.e., histological evidence of a direct local radiotherapy effect), rather than a cellular inflammatory response (which would be suggestive of histopathological changes induced by embolization or by chemotherapy; Figure 2) [6].