Previous analyses of data from trials included in ACCENT comparing surgery alone with surgery followed by fluorouracil (FU) -based chemotherapy demonstrated Paclitaxel human endothelial cells that patients age �� 70 years experienced a similar benefit from chemotherapy compared with younger patients.4 Recently, data from seven newer studies comparing either intravenous (IV) combination regimens with oxaliplatin or irinotecan or oral fluoropyrimidine chemotherapy with IV FU and leucovorin (LV) in stages II and III colon cancer were added to ACCENT (Table 1).5�C10 These studies included > 14,500 participants, of whom 18% were age �� 70 years. We sought to determine the impact of age on cancer recurrence and mortality after combination chemotherapy or oral fluoropyrimidines compared with single-agent IV FU as adjuvant colon cancer treatment.

Table 1. Adjuvant Colon Cancer Trials Included PATIENTS AND METHODS Study Design and Trial Selection The ACCENT group identifies and obtains individual patient data from phase III adjuvant trials in patients with colon cancer. Our analysis used seven phase III trials recently added to ACCENT that either compared standard IV FU and LV with combination regimens or oral fluoropyrimidine therapy.5�C10 The trials accrued 14,528 patients between 1997 and 2004 (Table 1). Beyond age, available data include patient sex, disease stage, treatment arm, survival status, and recurrence status at last follow-up time point. Data on toxicity and comorbidities were not consistently available across all studies and were therefore not included in this analysis.

Statistical Considerations All patients were included in the analyses according to the intention-to-treat principle. Disease-free survival (DFS) was defined as the time from random assignment to either recurrent disease or death, whichever occurred first. Overall survival (OS) was defined as the time from random assignment to death resulting from any cause. Time to recurrence (TTR) was defined as the time to colon cancer recurrence; deaths without recurrence were censored at the time of death. Second primary colon or noncolon tumors were not counted as events in the DFS and TTR analyses. The definitions of DFS and TTR used in the primary analysis of each individual trial were not consistent across the seven trials; thus, the definitions for our analyses may differ from those used in the original trials.

The primary analyses pooled individual patient data from the seven trials, stratified by the patient’s original trial, and considered age as a two-level dichotomous variable: age < 70 versus �� 70 years. Hazard ratios (HRs) were calculated using the Cox proportional hazards regression model, adjusting for sex, treatment arm, and disease stage. Models tested for an age-by-treatment interaction Entinostat using the likelihood ratio test.