Cancer of the appendix is extremely rare, Most patients are diagnosed after undergoing surgery for acute appendicitis or when an abdominal mass is seen during a CT scan for an unrelated condition.
Tumors of the appendix can be divided into two major groups: Carcinoid Tumors and Non carcinoid tumors. It’s the non carcinoid tumors that have a propensity to spread to the peritoneal cavity and those are discussed here
Non-carcinoid tumors of the appendix originate from the epithelial cells lining the inside of the appendix. Most of the cells creating these tumors produce a gelatinous material known as mucin. Due to the anatomic structure of the appendix and the mucin production of these tumors, patients with non-carcinoid tumors of the appendix are at risk for spread of tumor cells and mucin within the abdominal cavity. Most of these tumors are slow growing low grade tumors that remained confined to the peritoneal cavity for a long time. If left untreated, both tumor cells and mucin can accumulate over time and lead to life-threatening bowel obstruction and weight loss, loss of appetite, fatigue. Prognosis and treatment for these tumors depend on a number of patient and tumor-related factors.
Figure 1: A typical low grade mucinous tumor of the appendix, arises near the tip, ruptures and causes spread over the entire peritoneal cavity leading to pseudomyxoma peritonei
Appendiceal non carcinoid tumors can be of a high grade also. These tumors behave like colorectal cancer and are treated in the same way.
Figure 2: A typical high grade tumor that arises from the base andgrows along the large intestine. This tumor will cause peritoneal spread that is around the tumor and later spreads to other areas. It also has a propensity to spread to the glands and other organs of the body like the liver and lungs
This tumor may not produce any signs or symptoms till it has spread to the peritoneal cavity. Sometimes it produces a dull ache, bloating and discomfort.
This is one cancer which does not have a known cause. It s not a hereditary cancer, nor is it related to any particular lifestyle.
When the tumor is confined to the appendix, it may mimic acute appendicitis. Sometimes it is detected during surgery or as a mass on CT scan. When wide spread, it presents as a pseudomyxoma peritonei. Pseudomyxoma produces classic signs on a CT scan that helps in the diagnosis. Sometimes it may mimic ovarian cancer and the diagnosis is only made during for surgery for the same.
When the tumor is confined to the appendix, patients will undergo surgery to remove the appendix and/or right colon.
For patients with non-carcinoid tumors that have spread within the abdominal cavity, the most effective therapy appears to be a combined approach of cytoreductive (tumor debulking) surgery and hyperthermic intraperitoneal chemotherapy(HIPEC). (Read the section on HIPEC)
Low grade tumors have an excellent outcome with this kind of treatment, with patients surviving for 5-10 years and even more.
The high grade tumors are treated as colorectal cancer and do not have such a favourable outcome.