Colorectal cancer (CRC) is one of the most common malignancies in Western countries. Over the last 20 years, and the last decade in particular, the clinical outcome for patients with metastatic CRC (mCRC) has improved greatly due not only to an increase in the number of patients being referred for and undergoing surgical resection of their localised metastatic disease but also to a more strategic approach to the delivery of systemic therapy and an expansion in the use of ablative techniques. This reflects the increase in the number of patients that are being managed within a multidisciplinary team environment and specialist cancer centres, and the emergence over the same time period not only of improved imaging techniques but also prognostic and predictive molecular markers. Treatment decisions for patients with mCRC must be evidence-based. Thus, these ESMO consensus guidelines have been developed based on the current available evidence to provide a series of evidence-based recommendations to assist in the treatment and management of patients with mCRC in this rapidly evolving treatment setting.

Small bowel adenocarcinomas are rare tumours, but their incidence is increasing. Their most common primary location is the duodenum. The few studies that have collected data regarding small bowel adenocarcinoma are not homogeneous and are widely spread over time. Even though these tumours are most often sporadic, some predisposing diseases have been identified, among which Crohn's disease and genetic syndromes. Early diagnosis of small bowel adenocarcinoma remains difficult despite significant radiological and endoscopic progress. After surgical resection the main prognostic factor is node invasion; in this case, adjuvant chemotherapy can be expected to be beneficial, although this has not been established by randomised trials. For metastatic disease, platinum-based chemotherapy seems to be the most effective treatment. Targeted therapies have not yet been evaluated in this type of cancer.

Opinion Statement TNM stage remains the key determinant of patient prognosis after surgical resection of colorectal cancer (CRC), and informs treatment decisions. However, there is considerable stage-independent variability in clinical outcome that is likely due to molecular heterogeneity. This variability underscores the need for robust prognostic and predictive biomarkers to guide therapeutic decision-making including the use of adjuvant chemotherapy. Although the majority of CRCs develop via a chromosomal instability pathway, approximately 12-15% have deficient DNA mismatch repair (dMMR) which is characterized in the tumor by microsatellite instability (MSI). Tumors with the dMMR/MSI develop from a germline mutation in an MMR gene (MLH1, MSH2, MSH6, PMS2), i.e., Lynch syndrome, or more commonly from epigenetic inactivation of MLH1 MMR gene. CRCs with dMMR/MSI status have a distinct phenotype that includes predilection for the proximal colon, poor differentiation, and abundant tumor infiltrating lymphocytes. Consistent data indicate that these tumors have a better stage-adjusted survival compared to proficient MMR or microsatellite stable (MSS) tumors, and may respond differently to 5-fluorouracil-based adjuvant chemotherapy. To increase the identification of dMMR/MSI patients in clinical practice that includes those with Lynch Syndrome, it is recommended that all resected CRCs to be analyzed for MMR status. Available data indicate that patients with stage II dMMR CRCs have an excellent prognosis and do not benefit from 5-FU-based adjuvant chemotherapy which supports their recommended management by surgery alone. In contrast, the benefit of standard adjuvant chemotherapy with the FOLFOX regiment in stage III dMMR CRC patients awaits further study and therefore, all patients should be treated with standard adjuvant FOLFOX.

ObjectiveTo evaluate sintilimab versus placebo in combination with chemotherapy (cisplatin plus paclitaxel or cisplatin plus 5-fluorouracil) as first line treatment of unresectable locally advanced, recurrent, or metastatic oesophageal squamous cell carcinoma.DesignMulticentre, randomised, double blind, phase 3 trial.Setting66 sites in China and 13 sites outside of China between 14 December 2018 and 9 April 2021.Participants659 adults (aged ≥18 years) with advanced or metastatic oesophageal squamous cell carcinoma who had not received systemic treatment.InterventionParticipants were randomised 1:1 to receive sintilimab or placebo (3 mg/kg in patients weighing <60 kg or 200 mg in patients weighing ≥60 kg) in combination with cisplatin 75 mg/m2 plus paclitaxel 175 mg/m2 every three weeks. The trial was amended to allow investigators to choose the chemotherapy regimen: cisplatin plus paclitaxel or cisplatin plus 5-fluorouracil (800 mg/m2 continuous infusion on days 1-5).Main outcome measuresOverall survival in all patients and in patients with combined positive scores of ≥10 for expression of programmed cell death ligand 1.Results659 patients were randomly assigned to sintilimab (n=327) or placebo (n=332) with chemotherapy. 616 of 659 patients (93%) received sintilimab or placebo in combination with cisplatin plus paclitaxel and 43 of 659 patients (7%) received sintilimab or placebo in combination with cisplatin plus 5-fluorouracil. At the interim analysis, sintilimab with chemotherapy showed better overall survival compared with placebo and chemotherapy in all patients (median 16.7 v 12.5 months, hazard ratio 0.63, 95% confidence interval 0.51 to 0.78, P<0.001) and in patients with combined positive scores of ≥10 (17.2 v 13.6 months, 0.64, 0.48 to 0.85, P=0.002). Sintilimab and chemotherapy significantly improved progression free survival compared with placebo and chemotherapy in all patients (7.2 v 5.7 months, 0.56, 0.46 to 0.68, P<0.001) and in patients with combined positive scores of ≥10 (8.3 v 6.4 months, 0.58, 0.45 to 0.75, P<0.001). Adverse events related to treatment occurred in 321 of 327 patients (98%) in the sintilimab-chemotherapy group versus 326 of 332 (98%) patients in the placebo-chemotherapy group. Rates of adverse events related to treatment, grade ≥3, were 60% (196/327) and 55% (181/332) in the sintilimab-chemotherapy and placebo-chemotherapy groups, respectively.ConclusionsCompared with placebo, sintilimab in combination with cisplatin plus paclitaxel showed significant benefits in overall survival and progression free survival as first line treatment in patients with advanced or metastatic oesophageal squamous cell carcinoma. Similar benefits of sintilimab with cisplatin plus 5-fluorouracil seem promising.Trial registrationClinicalTrials.gov NCT03748134.