3671 Background: Colorectal cancer is one of the most common malignancies in China. X (Xeloda) is an oral fluoropyrimidine that is preferentially converted to 5-FU by exploiting the higher concentrations of thymidine phosphorylase (TP) in tumors compared to normal tissue. When combined with radiotherapy (which also upregulates TP), X is highly active and well tolerated for the preoperative treatment of locally advanced rectal cancer. Because few Chinese data are available, we evaluated X chemoradiation in Chinese pts with advanced/relapsed disease. Methods: We enrolled 100 pts between Jun 2002 and Oct 2003. All had measurable advanced or relapsed rectal carcinoma, and adequate Karnofsky PS, bone marrow, renal and hepatic functions. Adjuvant fluoropyrimidines (≥1 months previously) and/or prior radiotherapy to sites other than those evaluated in the trial were permitted. Pts received a total radiation dose of 60 Gy (1.8 Gy/day) for approximately 6 weeks plus X 825 mg/m2 twice daily for the duration of radiotherapy. Results: Baseline characteristics of the 71 pts currently evaluable: 51 men, 20 women; median age 51 years (range 18–75); median Karnofsky PS 90 (range 60–100); 86% pts had one disease site, 14% had ≥2, the most common being the rectum (51%), pelvis (44%), and skin (7%). 92% pts received the full 6 weeks' treatment, 6% stopped at week 5, 1% each at weeks 3 and 4. To date, at treatment end 46/71 pts have responded (65%) with only 4 progressions. At 4 weeks post-chemoradiation, responses have been confirmed in 34/59 pts (59%), of which 8 are complete (15%). Median progression-free and overall survival have not yet been reached. There were no grade 4 and very few grade 3 adverse events (HFS, 3%; diarrhea, 3%; nausea, 1%), which were easily managed with dose adjustment and supportive treatment when required. Conclusions: X chemoradiation is active and very well tolerated in Chinese pts with advanced or relapsed rectal carcinoma, reflecting the results obtained in Europe and the US. Use of this convenient regimen in the neoadjuvant and recurrent settings is clearly warranted. Author Disclosure Employment or Leadership Consultant or Advisory Stock Ownership Honoraria Research Funding Expert Testimony Other Remuneration AstraZeneca Pharmaceuticals