Spontaneous Regression of Mismatch Repair-Deficient Colon Cancer: A Case Series

Spontaneous regression of cancer is a rare phenomenon, with 33 colorectal cancer cases reported between 1900 and 2020.1-4 Spontaneous regression is defined as the partial or complete disappearance of a tumor without treatment.1,3 Several factors may be involved in this process, including biopsy, mechanical stress, humoral factors, and infection.1,5 However, no concrete evidence for the mechanistic insights has been indicated.