Adjuvant chemotherapy for resected stage II and III colon cancer: comparison of two widely used prognostic calculators

Abstract

Two Web-based prognostic calculators (Adjuvant! and Numeracy) are widely used to individualize decisions regarding adjuvant therapy among patients with resected stage II and III colon cancer. However, these tools have not been directly compared. Hypothetical scenarios were formulated for the Numeracy calculator based on all potential combinations of age, lymph nodes status, tumor stage, and grade of tumor. These were then applied to three postsurgical therapy choices: observation, 5-fluorouracil (5-FU), or FOLFOX (5-FU, leucovorin, and oxaliplatin chemotherapy) to obtain the predicted 5-year disease-free survival (DFS) and overall survival (OS). Wilcoxon signed rank tests were used to compare the numerical predictions between the Adjuvant! and Numeracy calculators for each combination. A total of 192 hypothetical patient scenarios were obtained. For these patients, DFS and OS predictions from Adjuvant! were statistically significantly different than Numeracy (P <.05), except for four of 144 categories. While the estimated benefit in DFS and OS for 5-FU compared to surgery obtained from Adjuvant! and Numeracy were similar, the benefit in DFS and OS for FOLFOX over 5-FU, obtained from the Adjuvant! tool was slightly lower than that estimated from Numeracy. Among patients with resected stage II and III colon cancer, the DFS and OS estimates obtained from Numeracy and Adjuvant!, regarding the benefit of 5-FU over surgery, are similar, but the benefits of FOLFOX over 5-FU differ. Validation studies are needed to clarify the discrepancy and to assess the accuracy of these tools for predicting actual patient outcomes.

Figure 1

(A–F) Correlation of DFS estimates for different therapeutic modalities, ie, surgery alone, surgery + 5-FU, and surgery + FOLFOX, between the Adjuvant! and Numeracy colon cancer prognostic tools for all potential combinations of age, grade of tumor, stage of tumor or lymph node status of tumor, among males and females. Curved lines represent a lowess smoothed estimate of association.

Figure 2

(A–F) Correlation of OS estimates for different therapeutic modalities, ie, surgery alone, surgery + 5-FU, and surgery + FOLFOX, between the Adjuvant! and Numeracy colon cancer prognostic tools for all potential combinations of age, grade of tumor, stage of tumor or lymph node status of tumor, among males and females. Curved lines represent a lowess smoothed estimate of association.

Figure 3

(A–H) Calculated absolute difference in DFS and OS estimates for 5-FU over surgery, and FOLFOX over 5-FU, from both Adjuvant! and Numeracy colon cancer prognostic tools for all potential combinations of age, grade of tumor, stage of tumor or lymph node status of tumor, among males and females. Curved lines represent a lowess smoothed estimate of association.