[Expert consensus on primary tumor management for metastatic colorectal cancer (2026 edition)]

Advances in comprehensive treatment primarily based on drug therapy have significantly improved the prognosis of metastatic colorectal cancer (mCRC) in recent decades. Patients who undergo surgical resection or local treatment after conversion therapy demonstrate relatively better outcomes. Consequently, in clinical practice, an increasing number of mCRC treatments as well as the patients themselves are seeking a state of no evidence of diseases. The management of the primary tumor constitutes an important component of this approach; however, compared to locally advanced disease, mCRC presents numerous distinct characteristics. Within the framework of systemic treatment for metastatic colorectal cancer, there are still numerous issues, such as the indications, timing, risks versus benefits of the primary tumor management, feasibility of watch-and-wait strategies, surgical planning and principles, coordination with systemic treatment, and follow-up for primary tumor treatment. We have noticed substantial discrepancies between physician and patient perceptions, lack of professional consensus, non-standardized technical criteria, and insufficient in-depth research in this field. To address these issues, therefore, the Chinese Watch and Wait Database Research Collaboration Group (CWWD), together with Chinese Society of Colorectal Surgery, Chinese Medical Association, and Colorectal Cancer Committee, Chinese Anti-Cancer Association, and relevant experts to construct this consensus. Based on the multidisciplinary team (MDT) model and incorporating the latest evidence-based medical evidence and clinical practice, this consensus was formulated addressing clinical decision-making and surgical indications for primary tumor treatment in mCRC, preoperative assessment and management in special scenarios, principles of surgery and implementational techniques, as well as postoperative management and comprehensive rehabilitation. The aim is to provide guidance for precise and individualized management of the primary tumor in mCRC, to standardize clinical practice, to improve patients' long-term survival and quality of life, and ultimately enhance the overall diagnosis and treatment standards of colorectal cancer in China.