Appendiceal adenocarcinoma is a rare cancer originating in the appendix, a small finger-shaped organ in the lower right abdomen. It affects approximately 1 to 2 individuals per million annually in the United States. Recent studies indicate a slight increase in its incidence, particularly among those 50 to 55 years old, though it can occur at any age.
What is Appendiceal Adenocarcinoma?
The appendix is a small, tube-like pouch extending from the large intestine. Its exact function is unclear, though some theories suggest an immune system role. Appendiceal adenocarcinoma develops from the epithelial cells lining the appendix. These cells produce mucin, a jelly-like substance that helps protect the intestinal lining.
Several types of appendiceal adenocarcinoma exist. Mucinous and non-mucinous types are common. Mucinous adenocarcinoma produces mucin, which can accumulate and spread cancerous cells throughout the abdominal cavity if the appendix ruptures. This can lead to pseudomyxoma peritonei (PMP), where mucin builds up in the abdomen, causing pressure on other organs. Non-mucinous or colonic-type adenocarcinoma behaves similarly to colorectal cancer and often develops near the base of the appendix. Other types include goblet cell carcinoids and signet-ring cell adenocarcinomas, which are aggressive.
Appendiceal adenocarcinoma is distinct from acute appendicitis, a sudden inflammation of the appendix. While both cause abdominal pain, appendiceal adenocarcinoma involves uncontrolled growth of abnormal cells forming a tumor. It is sometimes discovered incidentally during surgery for suspected appendicitis.
Signs and Diagnosis
Appendiceal adenocarcinoma often presents with non-specific symptoms, making early detection challenging. Patients may experience vague abdominal discomfort, bloating, or changes in bowel habits like constipation or diarrhea. In many cases, the cancer is discovered incidentally during imaging tests or surgical procedures for other conditions, such as suspected appendicitis or ovarian masses. Over half of individuals with this cancer may not experience symptoms at all.
When appendiceal cancer is suspected, diagnosis involves imaging and pathological examinations. Computed tomography (CT) scans or magnetic resonance imaging (MRI) are used to visualize the abdomen and pelvis. These scans can reveal an enlarged or abnormal appendix, tumors, or mucin spread within the abdominal cavity.
A definitive diagnosis relies on a biopsy, obtaining a tissue sample for microscopic examination by a pathologist. This biopsy is often taken during surgery, such as an appendectomy. Pathological examination identifies cancer cells and determines the tumor’s specific type and grade. Blood tests may also check for elevated tumor markers, such as carcinoembryonic antigen (CEA) or CA 19-9, associated with certain cancers. Staging the cancer, which determines its spread, is important for guiding treatment decisions.
Treatment Strategies
Surgical intervention is the primary approach for treating appendiceal adenocarcinoma. For very early-stage disease confined to the appendix, a standard appendectomy may be sufficient. If the tumor is larger or has spread beyond the appendix, a more extensive procedure called a right hemicolectomy might be performed, involving the removal of the appendix along with a portion of the right colon and nearby lymph nodes.
For advanced or mucinous types of appendiceal adenocarcinoma, particularly when cancer has spread within the abdominal cavity, a specialized treatment is Cytoreductive Surgery (CRS) combined with Hyperthermic Intraperitoneal Chemotherapy (HIPEC). CRS is an extensive surgical procedure where all visible tumors and affected tissues from the abdominal cavity are meticulously removed.
Following cytoreductive surgery, HIPEC involves circulating a heated chemotherapy solution directly within the abdominal cavity for a short period. The heat enhances its penetration into tissues and helps destroy any remaining microscopic cancer cells or hidden tumors. This direct delivery allows for a higher concentration of chemotherapy drugs to reach cancer cells within the abdomen, with fewer systemic side effects compared to traditional intravenous chemotherapy. Systemic chemotherapy, administered intravenously, may also be used for cases where the cancer has spread beyond the abdomen or as an additional treatment after surgery. The choice of chemotherapy regimen often draws from treatments used for colorectal cancer, though appendiceal cancer has different biological characteristics.
Outlook and Ongoing Care
The long-term outlook for individuals with appendiceal adenocarcinoma is influenced by several factors. These include the cancer’s stage at diagnosis, the tumor’s specific histological type (e.g., mucinous versus non-mucinous, low-grade versus high-grade), and the completeness of surgical removal. Low-grade tumors have a more favorable prognosis. Conversely, aggressive tumors or those that have spread extensively tend to have a lower survival rate.
Long-term follow-up and surveillance are important for monitoring for any signs of cancer recurrence. This involves regular imaging scans and periodic blood tests to check tumor marker levels. The frequency of these follow-up appointments and tests is determined by the patient’s individual circumstances and the nature of their disease. Managing this rare disease requires a multidisciplinary team of specialists, including surgical oncologists, medical oncologists, and pathologists, working together in specialized cancer centers.