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Gastrointestinal Cancer Stereotactic Radiotherapy for Liver Metastases Rute Pocinho, MD 1 and David Roberge, MD 2 1. Radiation Oncology Resident, Department of Radiotherapy, Francisco Gentil Portuguese Oncology Institute of Lisbon; 2. Department Head, Radiation Oncology, Notre Dame Hospital, Montreal Abstract Liver metastases are common in oncologic patients, causing substantial morbidity and mortality. Systemic therapy is now standard palliative treatment for most patients with liver metastases, often providing transient responses and increased overall survival. In selected oligometastatic patients, local treatment can lead to long disease-free intervals and even permanent disease control. Although surgery remains the gold standard of local treatments, most patients will not be appropriate surgical candidates. For these patients, alternate local treatments have been developed. Among these, stereotactic body radiotherapy (SBRT) presents an attractive non-invasive option for selected patients with limited hepatic involvement. This article reviews the development, indications, methods, and results of SBRT in the management of liver metastases. Keywords Stereotactic body radiotherapy, liver metastases, colorectal cancer, radiotherapy, review Disclosure: The authors have no conflicts of interest to declare. Received: January 8, 2012 Accepted: January 13, 2012 Citation: Oncology & Hematology Review, 2012;8(1):43–7 Correspondence: David Roberge, MD, Head, Department of Radiation Oncology, 1560 Sherbrooke Street East, Lachapelle Pavilion, room TS-3340, Montreal, Quebec, Canada H2L 4M1. E: david.roberge.chum@ssss.gouv.qc.ca The liver is a common site of metastatic disease from some of the most prevalent malignancies, in particular gastrointestinal tumors for which metastatic deposits travel through the portal venous system. Approximately one-third of patients with solid tumors will develop liver metastases. In a large autopsy series the prevalence of liver involvement was 86 % for pancreatic cancer, 60 % for breast cancer, and 42 % in colorectal cancer. 1 Hepatic involvement is often life-limiting and can result in severe morbidity. Approximately half of metastatic deaths from breast and prostate cancers are associated with liver metastases. Death due to colorectal cancer is frequently related to liver metastases, often as the only site of metastatic disease. Background to the Role of Stereotactic Body Radiotherapy Ablative Therapy of Liver Metastases Systemic therapy is usually the primary therapy for metastatic liver disease, 2 as it may allow for transitory responses and increased median survival. For patients with metastatic colorectal cancer treated with current palliative chemotherapy, median survival now approaches two years. 3 Although whole liver radiotherapy has long been abandoned as an anti-cancer therapy, current (infrequent) use in symptomatic patients may still offer symptomatic relief. 4 The goal of aggressive local treatment is long-term disease control for selected patients. 5–8 Its benefits are now supported by large retrospective series. With a long history, surgical resection remains the gold standard © TOUCH BRIEFINGS 2012 local treatment of hepatic metastases—typically of colorectal origin. 2,9 Surgery is associated with an acute risk of death (typically in less than 5  %) 10 but can lead to five-year overall survival rates of up to 58  %. 10–13 When Wilson and Adson retrospectively analyzed patients with limited liver metastases of colorectal cancer, approximately one-quarter of the resected patients were alive at five years. All long-term survivors in this series had solitary metastases, while none of the patients with multiple metastases or comparable non-resected patients were alive at five years. 14 Adson et al. reported similar results, with 25 % five-year survival rate for resected patients versus 2.5 % in a non-resected group. 15 Fong et al. studied 456 consecutive patients with liver metastases of colorectal cancer resections. They reported a 38  % five-year survival rate with a median survival of 46 months. 10 Despite the apparent benefits of surgery, clinical and technical limitations narrow eligibility to metastasectomy. Limitations may relate to: location of the metastases; surgical plans unable to preserve sufficient liver parenchyma; medical comorbidities; or patient refusal. Thus only 10–25  % of patients with liver metastases from colorectal cancer can benefit from curative resection. 2,16 New therapeutic options enable radical treatment instead of, or in combination with, surgery. Minimally invasive thermo-ablative procedures such as radiofrequency ablation (RFA), microwave ablation, cryotherapy, or laser-induced thermo-therapy have been developed. Complementing and competing with these is stereotactic body radiotherapy (SBRT)—a 43