Understand the significance of MSI-H status in Stage II Colon Cancer

A 55 yo old man was diagnosed with and underwent surgical resection with end to end anastomosis 4 weeks ago for a poorly differentiated ascending colon adenocarcinoma. The tumor was 2.8 cm across and invaded through the muscularis propria into pericolorectal tissues. Fifteen lymph nodes were resected and none were positive for adenocarcinoma. Molecular analysis confirmed the presence of MSI-H. The CT scan of the chest, abdomen and pelvis showed no distant metastasis. He healed well and was referred to Oncology department.

Which of the following is the most appropriate option?