Medullary Carcinoma of the Colon (MCC) is a rare histological subtype of colon cancer, and there is currently no recognized optimal treatment plan for it, with its prognosis remaining unclear. The aim of this study is to analyze the independent prognostic factors for MCC patients and develop and validate nomograms to predict overall survival (OS). A total of 760 patients newly diagnosed with MCC from 2004 to 2020 were selected from the Surveillance, Epidemiology, and End Results (SEER) database. All patients were randomly allocated to a training group and a validation group in a 7:3 ratio. Univariate and multivariable Cox regression analyses were conducted to identify prognostic factors and construct nomograms. The nomogram prediction model was evaluated and validated using receiver operating characteristic (ROC) curves, calibration curves, and decision curve analysis (DCA). The study found that elderly women are more susceptible to MCC, and the ascending colon and cecum are the most common sites of involvement. MCC is poorly differentiated, with stages II and III being the most common. Surgery is the primary treatment for MCC. The prognosis for patients with stage IV MCC is poor, with a median survival time of only 10 months. Independent prognostic factors for MCC include age, N stage, M stage, surgery, chemotherapy, and tumor size. Among them, age < 75 years and completion of chemotherapy were protective factors for colon medullary carcinoma, while N2 (HR = 2.18, 95%CI 1.40-3.38), M1 (HR = 3.31, 95%CI 2.01-5.46), no surgery (HR = 27.94, 95%CI 3.69-211.75), and tumor diameter > 7 cm (HR = 1.66, 95%CI 1.20-2.30) were risk factors for colon medullary carcinoma. The results of ROC, AUC, calibration curves, and DCA demonstrate that the nomogram prediction model exhibits good predictive performance. We have updated the demographic characteristics of colon medullary carcinoma and identified age, N staging, M staging, surgery, chemotherapy and tumor size as independent prognostic factors for colon medullary carcinoma. Additionally, we have established nomograms for prognostic prediction. These nomograms can provide personalized predictions and serve as valuable references for clinical decision-making.

Medullary carcinoma (MC) is a rare subtype of colorectal cancer, which presents with poorly differentiated histology and is often confused with conventional adenocarcinoma of the colon. While this form of colorectal cancer is rare, it often does not meet the high-risk criteria to qualify for adjuvant chemotherapy even with a favorable prognosis. Diagnosis of MC is a proven difficulty because of the lack of immunohistochemical stains on pathology seen in adenocarcinoma of the colon. Unlike adenocarcinoma of the colon, distant metastasis is rare. Patients diagnosed with MC have one- and two-year survival rates of 93% and 74%, respectively. The patient was a 75-year-old female diagnosed with MC of the sigmoid colon and a large uterine fibroid. In this case report, we discuss the high-risk indications of colorectal cancer and the recommended treatment of patients with stage II MC of the colon.

BACKGROUND: Most colon cancers are adenocarcinoma of the colon, which present with a typical histological type. However, a relatively newly-recognized subtype, called medullary carcinoma of the colon, has been characterized. This type is generally divided into subtypes of poorly-differentiated and undifferentiated medullary carcinoma. Only a handful of studies have been conducted thus far, mostly focusing on immunohistochemical and clinical characteristics of the disease.
METHODS: Herein we present two cases seen at our hospital within one academic year. The first is the case of a 79-year-old African-American woman, who presented with generalized weakness and gait unsteadiness ultimately diagnosed with a Stage IIIB medullary carcinoma of the proximal colon at the time of surgery, but later found to have metastases to a single paraesophageal lymph node. The second is a case of a 79-year-old Caucasian woman, who presented with several weeks of malaise, nausea, and diarrhea leading to diagnosis of a stage IIB medullary colon carcinoma now receiving chemotherapy.
CONCLUSIONS: Although these tumors tend to be right-sided and therefore present at an advanced stage, distant metastasis is rare at presentation and is primarily to the liver or regional lymph nodes. Only one study has been performed regarding short-term outcomes, which failed to reach statistical significance, but trended towards better prognosis compared to poorly-differentiated and undifferentiated colonic adenocarcinomas.