SCOT: tumor sidedness and the influence of adjuvant chemotherapy duration on disease free survival (DFS)
Saunders, Mark P Iype, Rohan Kelly, C. Crosby, J. Kerr, R. Harkin, A. Allan, K. McQueen, J. Pearson, S. R. Cassidy, J.
Saunders, Mark P
Iype, Rohan
Kelly, C.
Crosby, J.
Kerr, R.
Harkin, A.
Allan, K.
McQueen, J.
Pearson, S. R.
Cassidy, J.
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Abstract
Aim: Patients with loco-regional right-sided colorectal tumors have a worse overall survival (OS). Here we investigate the difference in disease free survival (DFS) between colorectal patients with right and left sided tumors in the SCOT study.
Methods: The SCOT study showed 3-months of oxaliplatin-containing adjuvant chemotherapy (OxFp) is non-inferior to 6-months for patients with stage III and high-risk stage II colorectal cancer. We divided the cohort into patients with left and right sided tumors, and evaluated the effect on DFS and the principle 3 versus 6-months analysis.
Results: 6088 patients with Stage III/high risk Stage II colorectal cancers were randomized between 27th March 2008 and 29th November 2013 from 244 centers internationally. In February 2017 (3-years FU) information on sidedness was available for 3309 patients (1238 R-sided, 2071 L-sided). Patients with right-sided tumors had a significantly worse DFS (3-year DFS right: 73.3% (se = 1.3%), left: 80.2% (se = 0.9%) HR 1.423 (95% CI 1.237-1.637; P < .0001). Adjusting for T and N-stage reduced the HR to 1.230 (95% CI 1.066-1.420, P = .005). The data did not suggest that sidedness affected the impact of chemotherapy duration on 3-year DFS (R: HR 1.024 [0.831-1.261], L: HR 0.944 [0.783-1.139]). Test for heterogeneity, P = .571. Further sub-set analysis was limited due to cohort size.
Conclusions: This is the first study to show that unselected patients with right-sided tumors had a worse DFS compared to left-sided tumors. Tumor sidedness did not impact upon the 3-months versus 6-months comparison in SCOT.
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Date
2023
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Article
Citation
Saunders MP, Iype R, Kelly C, Crosby J, Kerr R, Harkin A, et al. SCOT: Tumor Sidedness and the Influence of Adjuvant Chemotherapy Duration on Disease Free Survival (DFS). Clinical colorectal cancer. 2023 Feb 22. PubMed PMID: 36967267. Epub 2023/03/27. eng.