Gastrointestinal stromal tumours: ESMO Clinical Practice Guidelines for diagnosis, treatment and follow-up.

diagnosis When small oesophagogastric or duodenal nodules <2 cm in size are detected, endoscopic biopsy may be difficult, and laparoscopic/laparotomic excision may be the only way to get to a histological diagnosis. Many of these small nodules, if diagnosed as GIST, will be low risk, or entities whose clinical significance remains unclear. Therefore, the standard approach to these patients is endoscopic ultrasound assessment and then follow-up, reserving excision for patients whose tumour increases in size or becomes symptomatic. Alternatively, the decision can be shared with the patient to make a histological assessment. If follow-up is the choice, an evidence-based optimal surveillance policy is lacking. A logical choice may be to have a short-term first control (e.g. at 3 months), and then, in the case of no evidence of growth, a more relaxed follow-up schedule may be selected. In histologically proven small GIST, standard treatment is excision, unless major morbidity is expected. Alternatively, the decision can be shared with the patient to follow up the lesion, in the case of a low-risk GIST. However, the standard approach to rectal (or recto-vaginal space) nodules is biopsy/excision after ultrasound assessment regardless of the tumour size, because the risk of a GIST at this site is higher and the local implications for surgery are more critical. However, a follow-up policy may be an option, to be shared with the patient, in the case of small lesions. On the other hand, the standard approach to nodules >2 cm in size is biopsy/excision, because, if GIST, they imply a higher risk. If there is an abdominal nodule not amenable to endoscopic assessment, laparoscopic/laparotomic excision is the standard approach. If there is a bigger mass, especially if surgery is likely to be a multivisceral resection, multiple core needle biopsies are the standard approach. They should be obtained preferably through endoscopic ultrasound guidance, or otherwise through an ultrasound/CT-guided percutaneous *Correspondence to: ESMO Guidelines Working Group, ESMO Head Office, Via L. Taddei 4, CH-6962 Viganello-Lugano, Switzerland; E-mail: [email protected]