10.

Treatment principles for synchronous metastatic rectal cancer^a

Stratificationb		Class I recommendation	Class II recommendation	Class III recommendation
Primary lesion	Metastatic lesion
a, Comprehensive consideration of local treatment for primary rectal cancer and systemic treatment for metastases is required for synchronous metastatic rectal cancer. Rational arrange of the two aspects is needed under the multidisciplinary team (MDT) framework, with prioritized treatment for the greater threat to health. b, The risk of local recurrence of rectal primary tumor was assessed by European Society for Medical Oncology (ESMO) classification. Medium risk: extremely low T2, low/medium/high T3a/b, N1−2 (non-extranodal implantation), MRF−, EMVI−. High risk: extremely low T3, low/medium T3c/d, N1−N2 (extranodal implantation), MRF−, EMVI+. Very high risk: very low T4, low/medium/high T3 with MRF+, T4b, lateral lymph node+. c, For the detailed content of radiotherapy, please refer to the 4.1.3 Treatment of cT3/cT4N+ rectal cancer. d, For details of systemic chemotherapy, see the relevant section for colon cancer. e, Synchronized or staged resection of rectal and distant metastatic cancer.
Resectable, ≤ moderate risk of recurrence	Resectable	Similar to Section 3.2.1.1 Treatment for initially resectable metastatic colon cancer
	Unresectable	Similar to 3.2.1.2 Treatment for initially unresectable metastatic colon cancer
Resectable, high and extremely high risk of recurrence	Resectable	Concurrent radiochemotherapyc + systemic therapyd + surgerye	Systemic therapyd ± concurrent radiochemotherapyc + surgerye	—
	Unresectable	Systemic therapyd MDT assessment of resectability	Short-course radiotherapy + systemic therapyd	—
Unresectable	Resectable	Systemic therapyd + concurrent radiochemotherapyc MDT assessment of resectability	Systemic therapyd ± radiotherapyc	—
	Unresectable	Systemic therapyd ± radiotherapyc	—	—