The purpose of this study is to seek the proper dose of capecitabine in post-operative concurrent chemotherapy for stage II/III elderly rectal cancer patients receiving radical surgery, and evaluate the toleration of this modality in such patients.

For those "younger" locally advanced (stage II/III) rectal cancer patients (usually means patients less than 70), it is suggested that after radical surgery, patients should receive concurrent chemo-radiation. Capecitabine is a widely used chemotherapy medicine under such condition. Based on experience, the investigators think this modality can also be tolerated by patients over 70, and will increase local control rate as which has been proved in younger ones. As the first step to test this hypothesis, we designed this phase I study to seek the proper dose of capecitabine, a widely used oral chemotherapy medicine, in postoperative concurrent chemo-radiation for stage II/III rectal cancer patients over 70, and to evaluate the safety of this modality in this group of patients.

Inclusion Criteria:

• rectal adenocarcinoma, pathological stage II/III(T3-4 or N+, UICC 2002), radical surgery received.
• interval between surgery and enrollment no less than two week and no more than 3 months.
• KPS status no less than 70; life expectancy no less than 6 months.
• without life-threatening complications, such as severe hypertension, coronary heart disease, cerebral vascular disease, uncontrolled diabetes, etc.
• without severe drug allergy history.
• hemoglobin >= 100g/L, white blood cell >= 3.5*10E9/L, neutrophil >= 1.5*10E9/L, platelet >= 100*10E9/L.
• Creatin <= 1.5* ULN(upper limit of normal), Total bilirubin <= 2.5 ULN, AST and AST <= 2.5* ULN, AKP <= 2.5*ULN
• do not receive chemotherapy before six months from enrollment.
• no previously pelvic irradiation history
• informed consent signed

Exclusion Criteria:

• other cancer history, except curable non-melanoma skin cancer or cervix in-situ carcinoma
• allergy history to thymidine phosphorylase
• previous pelvic irradiation history
• receiving adjuvant chemotherapy in six months before enrollment
• active infection existed
• severe complication, such as acute myocardial infarction in 6 months, uncontrolled diabetes ( Plasma glucose concentrations in any time of a day≥11.1mmol/L）, severe cardiac arrhythmia， etc.
• life expectancy less than 6 months
• estimated cannot finish treatment
• attend other clinical trials in four weeks before enrollment
• receive other anti-cancer treatment currently
• other conditions which regarded illegal by censors with full reasons. for example, some conditions may conflict from the protocol.

9 weeks