Background: Adjuvant oxaliplatin is now a standard treatment option for patients with early-stage colon cancer. However, treatment delivery and outcomes achieved in routine practice are not well described. Methods: All cases of colon cancer diagnosed in Ontario from 2002 to 2008 were identified using the Ontario Cancer Registry. Pathology reports were obtained for a 25% random sample to identify stage II and III cases; patients treated with adjuvant oxaliplatin were included in this analysis. Treatment records were reviewed to identify oxaliplatin dose reductions or omissions. Modified Poisson regression was used to evaluate factors associated with dose reduction/omission. Cox proportional hazards model was used to explore factors associated with cancer-specific survival (CSS) and overall survival (OS). Results: The study population included 532 patients; 88% (469/532) had stage III disease. The mean/median number of oxaliplatin cycles delivered was 10/12. A dose reduction/omission of oxaliplatin occurred in 54% of cases (288/532), and the dose was subsequently escalated in 34% of these (97/288). Women were more likely than men to have dose reduction/omission (relative risk, 1.29; 95% CI, 1.10–1.51). Dose reduction/omission was not associated with inferior CSS (hazard ratio [HR], 0.76; 95% CI, 0.51–1.14) or OS (HR, 0.81; 95% CI, 0.59–1.13). Five-year CSS and OS of all cases were 77% (95% CI, 72–81) and 72% (95% CI, 68–76), respectively. On-treatment mortality rates were 1% and 3% within 30 and 90 days of oxaliplatin, respectively. Conclusions: Dose reductions of adjuvant oxaliplatin are common in routine practice but are not associated with inferior survival. Long-term survival achieved in the general population is comparable to the results of clinical trials.
Natasha Satkunam, Xuejiao Wei, James J. Biagi, Sulaiman Nanji and Christopher M. Booth
Christopher M. Booth, Sulaiman Nanji, Xuejiao Wei, Yingwei Peng, James J. Biagi, Timothy P. Hanna, Monika K. Krzyzanowska and William J. Mackillop
Background: International guidelines recommend adjuvant chemotherapy (ACT) for patients with stage III colon cancer. Whether efficacy observed in clinical trials translates to effectiveness in routine practice is less well understood. Here we describe use and outcomes of ACT in routine practice. Methods: All cases of colon cancer treated with surgery in Ontario 2002–2008 were identified using the population-based Ontario Cancer Registry. Linked electronic records of treatment identified surgery and ACT use. Pathology reports were obtained for a random 25% sample of all cases; patients with stage III disease were included in the study population. Modified Poisson regression was used to evaluate factors associated with ACT. Cox proportional hazards model and propensity score analysis were used to explore the association between ACT and cancer-specific survival (CSS) and overall survival (OS). Results: The study population included 2,801 patients with stage III colon cancer; 66% (n=1,861) received ACT. ACT use rates varied substantially across age groups; 90% among patients aged 20 to 49 years versus 68% among those aged 70 to 79 years (P<.001). ACT use was inversely associated with comorbidity (P<.001) and socioeconomic status (P=.049). In adjusted analyses advanced age is associated with inferior CSS and OS. Use of ACT was associated with decreased risk of death from cancer (hazard ratio [HR], 0.63; 95% CI, 0.54–0.73) and decreased risk of death from any cause (HR, 0.63; 95% CI, 0.55–0.71). This result was consistent in the propensity score analysis. Conclusions: One-third of patients with stage III colon cancer in the general population do not receive ACT. Use of ACT in routine practice is associated with a substantial improvement in CSS and OS.