Abstracts
2000 Digestive Disease Week

# 2269 Selective Internal Radiation Therapy (SIRT) for the Treatment of Advanced Colorectal Liver Metastases.
Richard Strawson Stubbs, Rebecca Jane Cannan, Alex William Mitchell, Wellington, New Zealand

50 patients with advanced, non-resectable, colorectal liver metastases and a median age of 61.5yr were treated with SIRT between Feb 97 and June 99. Estimated liver involvement was <25% in 25 patients, 25-50% in 12 and >50% in 13. A titrated single dose of between 2.0-3.0 GBq of90Yttrium microspheres was injected into the hepatic artery via a surgically implanted hepatic artery port and followed at 4-weekly intervals by regional chemotherapy with 5FU 1.0g per day for 4 days by continuous infusion. SIRT was well tolerated though accompanied by liver pain and/or nausea for 24-48 hours in many patients. No treatment related mortality was encountered. Median Hospital stay after SIRT was 2 days. Responses to SIRT as indicated by falling tumour markers (CEA) and serial 3-monthly CT scans are shown in the Table below. Median CEA 1 and 2 months after SIRT (expressed as % of initial CEA) was 19% and 13%. Median survival from SIRT was 8.5 months (1.0-27.8) and estimated survival±sd at 6,12,18 and 24 months was 71.6±8.3%, 45.3±15.5%, 34.5±18.1% and 16.8±22.6%. Patients were arbitrarily assigned to two groups. Group 1 had no sign of extrahepatic metastases within 6 months of SIRT whereas Group 2 did. Median survival from SIRT for Group 1 patients (n=24) was 15.1 mo (1.0-28) with estimated survival±sd at 6,12,18 and 24 months of 83.3±5.4%, 69.3±8.7%, 56.0±11.0%, 30.6±19.0%. For Group 2 patients (n = 26) median survival was 6.3mo (1.25-18.8) and estimated survival at 6,12,18 months was 59.8±11.1%, 16.6±23.7%, 0±27.1%. This difference is statistically significant by Log- Rank test (p<0.001). SIRT is a highly effective and well tolerated modality for the regional treatment of extensive, non-resectable colorectal liver metastases. Tumour marker data suggests that substantial destruction of liver tumour can be achieved in over 90% of patients by a single treatment with SIRT. This benefit can be maintained in most patients with ongoing chemotherapy. Survival times for those treated, and particularly those who do not develop extrahepatic metastases for some time, do seem to be improved over expected natural history outcomes. SIRT warrants further use and investigation in patients with advanced colorectal liver metastases.