Tailoring adjuvant chemotherapy by circulating tumor DNA (ctDNA) in older patients with stage II-III colon cancer

Colorectal cancer is the third most frequent cancer worldwide and the fourth most common cause of cancer mortality [ [1] Arnold M. et al. Global patterns and trends in colorectal cancer incidence and mortality. Gut. 2017; 66: 683-691 Crossref PubMed Scopus (2841) Google Scholar ]. The average age of patients with colorectal cancer in Western countries is around 70 years old [ [2] Siegel R.L. Miller K.D. Jemal A. Cancer statistics, 2016. CA Cancer J Clin. 2016; 66: 7-30 Crossref PubMed Scopus (22348) Google Scholar ]. Surgery is the current gold standard for treating early-stage colon cancer, with adjuvant chemotherapy (ACT) in most cases to improve cure rates [ [3] Benson A.B. et al. Colon cancer, version 2.2021, NCCN clinical practice guidelines in oncology. J Natl Compr Cancer Netw. 2021; 19: 329-359 Crossref PubMed Scopus (436) Google Scholar ]. The goal of ACT in patients with colon cancer is to increase the likelihood of cure while minimizing the risk of toxicity. The ACT is the standard of care in stage III colon cancer [ [4] Shah M.A. et al. Impact of patient factors on recurrence risk and time dependency of oxaliplatin benefit in patients with colon cancer: analysis from modern-era adjuvant studies in the adjuvant colon cancer end points (ACCENT) database. J Clin Oncol. 2016; 34: 843 Crossref PubMed Scopus (102) Google Scholar ], while in stage II disease, additional clinical risk factors are used to optimize patient selection for adjuvant treatment [ [5] Labianca R. et al. Early colon cancer: ESMO clinical practice guidelines for diagnosis, treatment and follow-up. Ann Oncol. 2013; 24 (vi64-72) Abstract Full Text Full Text PDF Scopus (681) Google Scholar ]. Furthermore, the risk of toxicity is an important concern in aiding adjuvant treatment selection for individual patients.