Spontaneous Regression Of Advanced Transverse Colon Cancer With Deficient Mismatch Repair: A Case Report

Harata, S. 2023Colorectal cancer

Harata, S., Takahashi, H., Ando, N., Kato, A., Watanabe, K., Yanagita, T., Suzuki, T., Ushigome, H., Shiga, K., Ogawa, R., Matsuo, Y., Mitsui, A., Kimura, M., & Takiguchi, S. (2023). Spontaneous regression of advanced transverse colon cancer with deficient mismatch repair: a case report. Surgical case reports, 9(1), 64. https://doi.org/10.1186/s40792-023-01595-x

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Abstract

BACKGROUND: Spontaneous regression (SR) of cancer occurs in 1 in 60,000-100,000 patients. This phenomenon has been reported in almost all cancer types, most commonly neuroblastoma, renal cell carcinoma, malignant melanoma, and lymphoma/leukemia. However, SR in colorectal cancer (CRC) is extremely rare, particularly in advanced cases. Hence, this report describes a very rare case of spontaneous regression of advanced transverse colon cancer. CASE PRESENTATION: A 76-year-old female with anemia was diagnosed with a type II well-differentiated adenocarcinoma in the middle transverse colon. Two months later, a second colonoscopy examination was performed for preoperative marking, and it revealed tumor shrinkage and a shift to type 0-IIc morphology. Endoscopic tattooing was then performed, followed by a laparoscopic partial resection of the transverse colon with D3 lymph node dissection. However, the resected specimen contained no tumor, and colonoscopy showed no tumor remnants in the remaining colon. Histopathological examination revealed mucosal regeneration and a mucus nodule in between the submucosal and muscular layers, with no cancer cells detected. Immunohistochemical analysis revealed the loss of MutL homolog 1 (MLH1) and postmeiotic segregation increased 2 (PMS2) expression in the cancer cells of biopsied specimens, suggesting deficient mismatch repair (dMMR). The patient continues to be followed up until 6 years postoperatively, and no recurrence has been observed. In this study, we also reviewed similar reported cases of spontaneous regression of cancer involving dMMR. CONCLUSION: This study presents a rare case of spontaneous regression of advanced transverse colon cancer wherein dMMR is strongly involved. However, further accumulation of similar cases is needed to elucidate this phenomenon and to develop new treatment strategies for CRC.

Case Details

Disease Location

Colon

Personal Characteristics

76-year-old female. Her previous medical history included endoscopic submucosal dissection 1 year prior for early gastric cancer, appendectomy, and hypertension. The patient was postmenopausal.

Clinical Characteristics

Presented with anemia. Laboratory examinations revealed pancytopenia, suggesting myelodysplastic syndrome. Ca19-9 levels were elevated. Colonoscopy revealed a type ii tumor, which measured 30 mm in diameter and was located in the middle transverse colon. Biopsy demonstrated a well-differentiated adenocarcinoma. Barium enema examination revealed an arc-shaped deformation in the transverse colon, further indicating that the lesion was a type ii tumor. After size reduction, laparoscopic partial resection of the transverse colon with d3 lymph node dissection was performed

Remission Characteristics

Two months later, a colonoscopy revealed that the tumor had shrunk to a diameter of 15 mm and a shift to type 0–iic morphology. Surgical specimen examination revealed mucosal regeneration and a mucus nodule in between the submucosal and muscular layers, with no residual cancer cells noted.