Assimilation of evidence-based medicine into clinical practice: Adjuvant radiotherapy in the multidisciplinary treatment of rectal cancer.

Abstract

552 Background: Implementation of evidence based standards is recognized to be problematic. Level 1 evidence supports the superiority of neoadjuvant therapy for stage II/III rectal cancer. The purpose of this study was to determine to what extent evidence based medicine has impacted clinical practice. Methods: Stage II/III rectal cancer patients undergoing surgery from 1998-2007 were identified in the SEER tumor registry using SEER*Stat 6.2. Variables were extracted and analyzed in SPSS; trends were evaluated with regression models and survival with log rank test. Results: A total of 25,129 patients were identified, 15,769 (63%) were treated with adjuvant radiotherapy. A majority were > 60 years old (56%), white (82.8%), male (60.9%), had stage III cancers (59.2%) and treated with neoadjuvant radiotherapy (54.5%). Significant changes in timing of adjuvant radiotherapy were noted over the study period. In 1998 28.1% of patients were treated neoadjuvantly, this increased to 74% in 2007, a 263% increase. Scatter plot best fit lines intersect in approximately year 2002, p value of trend <0.001. On univarate analysis race (p=0.018), sex (p<0.001), year of diagnosis (p<0.001), age (p<0.001), and stage (p<0.001) were associated increased likelihood of neoadjuvant radiotherapy. Logistic regression found male sex (OR 1.14, p<0.001), year (OR 1.223, p<0.001) and stage II (OR 1.39, p<0.001) were predictors of neoadjuvant therapy. Significant increases in preoperative radiotherapy were observed for all races and cancer stages (p<0.001). There was a significant survival advantage for those treated with adjuvant radiotherapy, median survival 39 vs. 93 months p<0.0001. There, however, was no survival advantage to neoadjuvant vs. postoperative radiotherapy, median survival 94 vs. 93 months, p=0.749. Conclusions: When adjuvant radiotherapy is utilized, there has been rapid adoption of evidence based standards for Stage II/III rectal cancer. However, substantial numbers of patients are not receiving care recognized to improve outcomes.