From the Guidelines
Mucinous adenocarcinoma of the colon is a specific subtype of colon cancer characterized by cancer cells that produce excessive amounts of mucin, making up at least 50% of the tumor volume, as defined by the international collaboration on cancer reporting (ICCR) in 2022 1.
Definition and Characteristics
Mucinous adenocarcinoma is recognized and defined as a subtype of adenocarcinoma with >50% of the tumor comprised of pools of extracellular mucin, containing malignant glands, or individual tumor cells, according to the ICCR recommendations 1. This cancer typically appears as a gelatinous mass within the colon wall and is more commonly found in the proximal (right) colon.
Clinical Features and Treatment
Mucinous adenocarcinomas tend to be diagnosed at more advanced stages compared to conventional adenocarcinomas, often with regional lymph node involvement or distant metastasis. They are associated with microsatellite instability and certain genetic mutations, such as the activating BRAF V600E mutation 1. Treatment generally follows standard colorectal cancer protocols, including surgical resection of the tumor and affected lymph nodes, followed by chemotherapy regimens. The prognosis for mucinous adenocarcinoma is generally considered slightly worse than conventional adenocarcinoma, particularly in rectal cancers, though outcomes vary based on stage at diagnosis, microsatellite status, and response to treatment.
Prognosis and Outcomes
Patients with proximal colon tumors, where mucinous adenocarcinomas are more frequently found, have a worse prognosis independently of the applied treatments, as noted in the ESMO clinical practice guideline for diagnosis, treatment, and follow-up of metastatic colorectal cancer in 2023 1. However, the treatment approach should prioritize standard colorectal cancer protocols, including surgical resection and chemotherapy, to optimize outcomes for patients with mucinous adenocarcinoma of the colon. Key factors influencing prognosis include stage at diagnosis, microsatellite status, and response to treatment, highlighting the importance of personalized management strategies.
From the Research
Definition and Characteristics of Mucinous Adenocarcinoma of the Colon
- Mucinous adenocarcinoma of the colon is a distinct subtype of colorectal cancer characterized by the presence of abundant extracellular mucin, which accounts for at least 50% of the tumor volume 2, 3.
- It is found in 10%-20% of colorectal cancer patients and occurs more commonly in female and younger patients 2.
- Mucinous adenocarcinoma is more frequently located in the proximal colon and diagnosed at an advanced stage 2, 3, 4.
Molecular Features and Prognosis
- Mucinous adenocarcinoma is associated with the overexpression of mucin 2 (MUC2) and mucin 5AC (MUC5AC) proteins 2.
- It shows higher mutation rates in the fundamental genes of the RAS/MAPK and PI3K/Akt/mTOR pathways 2.
- The prognosis of mucinous adenocarcinoma compared to non-mucinous colorectal adenocarcinoma is debatable, with some studies suggesting a poorer response to chemotherapy and a higher rate of microsatellite instability (MSI) 2, 5, 3.
- The poor prognosis of rectal mucinous adenocarcinoma has been confirmed by various studies, while the prognosis of colonic mucinous adenocarcinoma is still controversial 3, 4.
Diagnosis and Treatment
- Biopsy is the main diagnostic method for mucinous adenocarcinoma, but magnetic resonance imaging is superior in accuracy, especially for rectal carcinoma 3.
- Surgical resection is the primary potentially curative approach for mucinous adenocarcinoma, and adjuvant chemotherapy may be used in some cases 4.
- The management of mucinous adenocarcinoma requires a multidisciplinary approach, including input from surgeons, pathologists, oncologists, and radiologists 5.