Abstract 401P
Background
The pivotal IDEA trial showed marginal differences in survival outcomes for 3 vs 6 months of adjuvant chemotherapy (ACT) in stage II and III colon cancer (CC). Severe treatment toxicity was substantially lower in the short treatment regimen. Therefore, in 2017 the Dutch colorectal cancer (CRC) guideline was revised and currently recommends 3 months of oxaliplatin (OX)-based ACT. In addition, the definition of high-risk stage II CC was restricted to include only pathological T4 (pT4) tumors (instead of presence of poor differentiation, lymph node harvest <10, lymphovascular invasion and perforation/obstruction at presentation). We evaluate adherence to the revised guideline in The Netherlands.
Methods
From the Netherlands Cancer Registry (NCR) all 16,721 patients ≥18 years with resected high-risk (risk factors according to previous guideline) stage II and III CC during 2015-2019 were selected. The impact of implementation of guidelines was analyzed by comparing differences in patient characteristics (Chi-square tests) and in duration of ACT between incidence years (one-way analysis of variance). Treatment patterns and ACT regimens were analyzed according to stage and age.
Results
Of all patients receiving ACT (n=8,170), the proportion treated with CAPOX increased from 75% in 2015/2016 (before guideline revision) to 83% in 2018/2019 (after guideline revision). Intravenous 5-fluorouracil containing ACT was administered in 5% of patients in 2015/2016 and decreased to 2% in 2018/2019. Mean duration of OX-based ACT decreased from 18.6 (± 8.0) weeks in 2015 to 9.5 (± 3.8) weeks in 2019. The proportion of patients receiving ACT was stable over time, 61-69% in stage III and 26-29% in pT4 stage II. ACT in patients with previous high-risk pT3N0 disease decreased from 15% to 3% before and after guideline revision. At the same time the use of OX-based ACT increased from 27% to 49% in patients ≥75 years old.
Conclusions
The revised Dutch CRC guideline, recommending 3 months of ACT and restriction of ACT in stage II to pT4N0 CC, was rapidly implemented in clinical practice. The shortened duration of ACT led to an increase in elderly patients that received OX-based ACT.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.