Effect of Adjuvant Chemotherapy on Stage II Rectal Cancer Outcomes After Preoperative Short-Course Radiotherapy.
Adjuvant chemotherapy (AC) is offered to patients with stage II rectal cancer, but its use is controversial. We examined population-based outcomes of patients with pathologic stage II rectal cancer treated with AC after preoperative short-course radiotherapy.



We included patients diagnosed with pathologic stage II tumors from 1999 to 2009 in British Columbia. The disease-specific survival (DSS), relapse-free (RFS), and overall survival (OS) were assessed. Multivariate models adjusting for age, gender, Eastern Cooperative Oncology Group, and high-risk features (ie, pT4, poor differentiation, < 12 lymph nodes removed, lymphovascular invasion, perineural invasion, or obstruction or perforation) were constructed.



Of 851 patients reviewed, 330 had received preoperative short-course radiotherapy, of whom 123 (37%) subsequently received AC. Patients treated with AC were younger (median age 61 vs. 73 years; P < .0001), reported better Eastern Cooperative Oncology Group status (P < .0001), and had more high-risk features (P < .0001). On univariate analysis, AC was associated with improved DSS (hazard ratio [HR], 0.58; 95% confidence interval [CI], 0.36-0.94; P = .028), RFS (HR, 0.62; 95% CI, 0.39-0.98; P = .043), and OS (HR, 0.42; 95% CI, 0.30-0.59; P < .0001). On multivariate analysis, these outcomes were not significant (DSS HR, 0.83; 95% CI, 0.43-1.61; P = .58; RFS HR, 0.82; 95% CI, 0.44-1.50; P = .51; OS HR, 0.62; 95% CI, 0.37-1.03; P = .064). Subgroup analysis suggested AC improved DSS (HR, 0.25; 95% CI, 0.07-0.89; P = .033), RFS (HR, 0.24; 95% CI, 0.07-0.85; P = .027), and OS (HR, 0.22; 95% CI, 0.069-0.70; P = .011) only in patients with ≥ 2-high risk features.



In the present population-based cohort of patients with stage II rectal cancer, AC did not improve the outcomes in unselected patients. In a small subgroup of patients with ≥ 2 risk factors, we noted improved outcomes with AC use.
Division of Medical Oncology, University of British Columbia, British Columbia Cancer Agency, Vancouver, BC, Canada.
Jonathan M
JM
Loree
Division of Medical Oncology, University of British Columbia, British Columbia Cancer Agency, Vancouver, BC, Canada.
Hagen F
HF
Kennecke
Division of Medical Oncology, University of British Columbia, British Columbia Cancer Agency, Vancouver, BC, Canada.
Daniel J
DJ
Renouf
Division of Medical Oncology, University of British Columbia, British Columbia Cancer Agency, Vancouver, BC, Canada.
Howard J
HJ
Lim
Division of Medical Oncology, University of Ottawa, The Ottawa Hospital Cancer Centre, Ottawa, ON, Canada.
Michael M
MM
Vickers
Cancer Control Research, Gastrointestinal Cancers Outcomes Unit Database, University of British Columbia, British Columbia Cancer Agency, Vancouver, BC, Canada.
Caroline H
CH
Speers
Division of Medical Oncology, University of British Columbia, British Columbia Cancer Agency, Vancouver, BC, Canada. Electronic address: WCheung@bccancer.bc.ca.
Winson Y
WY
Cheung
D000328:Adult; D000368:Aged; D059248:Chemoradiotherapy / Q000379:methods*; D017024:Chemotherapy, Adjuvant; D015331:Cohort Studies; D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D020360:Neoadjuvant Therapy; D016016:Proportional Hazards Models; D018714:Radiotherapy, Adjuvant; D012004:Rectal Neoplasms / Q000188:drug therapy* / Q000473:pathology* / Q000532:radiotherapy*; D012307:Risk Factors; D016896:Treatment Outcome
Chemoradiotherapy; Colorectal; Locally advanced; Rectal neoplasms; Risk factors