Abstract
Spontaneous regression (SR) of many malignant tumors has been well documented, with an approximate incidence of one per 60,000–100,000 cancer patients. However, SR of colorectal cancer (CRC) is very rare, accounting for less than 2% of such cases. We report a case of SR of transverse colon cancer in an 80-year-old man undergoing outpatient follow-up after surgical treatment of early gastric cancer. Colonoscopy (CS) revealed a Borrmann type II tumor in the transverse colon measuring 30 × 30 mm. Because the patient underwent anticoagulant therapy, we did not perform a biopsy at that time. A second CS was performed 1 week after the initial examination and revealed tumor shrinkage to a diameter of 20 mm and a shift to the Borrmann type III morphology. Biopsy revealed a poorly differentiated adenocarcinoma. One week after the second CS, we performed a partial resection of the transverse colon and D2 lymph node dissection. Histopathology revealed inflammatory cell infiltration and fibrosis from the submucosal to muscularis propria layers in the absence of cancer cells, leading to pathological staging of pStage 0 (T0N0). The patient had an uneventful recovery, and CS performed at 5 months postoperatively revealed the absence of a tumor in the colon and rectum. The patient continues to be followed up as an outpatient at 12 months postoperatively, and no recurrence has been observed.
Highlights
Spontaneous regression (SR) of a malignant tumor is defined as a partial or complete disappearance of a tumor without treatment or in response to a treatment that is considered inadequate to exert a significant influence on neoplastic disease [1]
A review of During the current investigation, only five cases of SR of primary colorectal cancer (CRC), including our case, have been reported since 2006 (Table 1) [6,7,8,9]. In four of these five cases, SR without lymph node metastasis was pathologically proven in surgical specimens, and the duration of confirmed SR was less than 6 months
In all cases except ours, tumor reduction was revealed after biopsy, and heavy inflammatory cell infiltration was observed in the biopsy and/or excised specimens from all cases
Summary
Spontaneous regression (SR) of a malignant tumor is defined as a partial or complete disappearance of a tumor without treatment or in response to a treatment that is considered inadequate to exert a significant influence on neoplastic disease [1]. We report a case of SR of transverse colon cancer in which we could morphologically observe the course of shrinkage. No lymph node or distant metastasis was detected (Fig. 2a, b). Partial surgical resection of the transverse colon and D2 lymph node dissection were performed. Immunohistochemical staining of the excised specimen revealed a significant amount of CD3+CD4+ T cells as well as CD20+ B cells and a few CD8+ T cells (Fig. 8). Immunohistochemical staining of the dissected lymph nodes revealed a significant amount of CD3 + CD4+ T cells and a few CD8+ T cells (Fig. 9). CS performed 5 months postoperatively revealed an absence of tumors in the colon and rectum, and his CA19-9 level decreased to within the normal range. The patient remains under outpatient follow-up at 12 months postoperatively, with no observed recurrence
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