Timing of adjuvant chemotherapy affects outcomes after colorectal cancer surgery
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Key takeaways:
- Patients who started adjuvant chemotherapy more than 6 weeks after colorectal cancer surgery achieved poorer DFS.
- Adverse events did not differ based on timing of adjuvant chemotherapy.
Timing of adjuvant chemotherapy initiation may affect outcomes among patients who undergo surgery for colorectal cancer, according to data published in JAMA Surgery.
An analysis of patients with high-risk stage II or stage III disease showed those who started adjuvant chemotherapy more than 6 weeks after surgery achieved shorter DFS.
“The results suggest that efforts toward facilitating the early start of adjuvant chemotherapy may improve long-term oncological outcomes,” Mikail Gögenur, MD, research fellow at Center for Surgical Science in Denmark, and colleagues wrote.
Background and methods
Surgery is the only curative treatment for patients with nonmetastatic colorectal cancer. Prior studies have assessed timing of adjuvant chemotherapy initiation; however, the subject has not been investigated in a large prospective, well-controlled trial, according to study background.
Gögenur and colleagues conducted a post hoc analysis of the randomized phase 3 SCOT trial to analyze the potential association between DFS and timing of adjuvant chemotherapy after colorectal cancer surgery.
The analysis included 5,719 patients (mean age, 63.4 years; 60.6% men) with high-risk stage II or stage III nonmetastatic colorectal cancer who underwent curative-intended surgery at one of 244 centers in six countries.
Under SCOT trial protocol, researchers randomly assigned patients to either 3 months or 6 months of adjuvant chemotherapy with fluoropyrimidine and oxaliplatin regimens.
In the post hoc analysis, Gögenur and colleagues analyzed outcomes based on whether patients started adjuvant chemotherapy less than 6 weeks or more than 6 weeks after surgery.
DFS served as the primary endpoint. Secondary endpoints included adverse events in the total treatment period or in the first cycle of adjuvant chemotherapy.
Results, next steps
Researchers determined 914 patients started adjuvant chemotherapy less than 6 weeks after surgery. The other 4,805 patients started chemotherapy more than 6 weeks after surgery.
A median 56 days (interquartile range, 41-66) elapsed between surgery and chemotherapy.
Median follow-up was 72 months (interquartile range, 47.3-88.1).
Researchers observed a higher 5-year DFS rate in the early chemotherapy initiation group (78% vs. 73.2%; adjusted HR = 1.24; 95% CI, 1.06-1.46).
Adjusted analyses showed no association with adverse events in the total treatment period (OR = 0.82; 95% CI, 0.65-1.04) or in the first cycle of treatment (OR = 0.77; 95% CI, 0.56-1.09).
Researchers acknowledged study limitations, including the fact SCOT trial participants were not randomly assigned according to adjuvant chemotherapy start. In addition, the mean age in the cohort — 63.4 years — was younger than the typical population of patients with colorectal cancer.
“Based on others’ and our findings in this field, efforts should be made to facilitate circumstances that allow patients to quickly recover from [colorectal cancer] surgery so adjuvant treatment can be initiated,” researchers wrote.
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Gögenur M, et al. JAMA Surg. 2024;doi:10.1001/jamasurg.2024.1555.
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