Pseudomyxoma peritonei (PMP) is a rare cancer characterized by the accumulation of mucin, a gelatinous substance, within the abdominal cavity. This condition typically originates from a tumor in the appendix, although other primary sites are possible. PMP is often referred to as “jelly belly” due to the significant buildup of this jelly-like material. Given its rarity, affecting approximately one to two people per million each year, PMP requires specialized management.
Understanding PMP Cancer
PMP most commonly originates from a mucinous tumor in the appendix. While the appendix is the primary source, PMP can also arise from other organs such as the colon, ovaries, or stomach, though these are less common. The disease spreads uniquely, with cancer cells and mucin disseminating within the peritoneal cavity, which lines the abdomen and covers its organs. Unlike many cancers, PMP rarely spreads through the bloodstream or lymphatic system to distant parts of the body.
Instead, the tumor cells and the mucin they produce accumulate and spread across the surfaces within the abdomen. This accumulation of gelatinous mucin can cause pressure on internal organs, leading to various complications. The condition is classified based on the appearance of the cancer cells under a microscope, typically as low-grade or high-grade mucinous tumors. Low-grade tumors grow slowly and are less aggressive, while high-grade tumors are more aggressive.
Symptoms and Diagnosis
Symptoms of PMP often develop slowly and can be non-specific, making early detection challenging. Common indicators include abdominal swelling or an increase in waist size, general abdominal discomfort, or pain. Changes in bowel habits, such as constipation, loss of appetite, or unexplained weight changes, can also occur as the mucin buildup affects digestive function. In women, PMP may sometimes be mistaken for ovarian issues due to similar symptoms like an enlarged ovary.
Diagnosis typically involves a combination of imaging techniques and tissue analysis. Computed tomography (CT) scans, magnetic resonance imaging (MRI), and sometimes positron emission tomography (PET) scans are used to visualize the extent of mucin accumulation and tumor spread within the abdomen. While imaging provides important clues, a definitive diagnosis requires a biopsy. A biopsy involves taking a tissue sample, often during a laparoscopic procedure or exploratory surgery, for microscopic examination to confirm PMP’s presence and grade. Tumor markers like Carcinoembryonic Antigen (CEA) and Cancer Antigen 125 (CA-125) may be elevated in blood tests and can support diagnosis or monitor disease activity, but they are not definitive on their own.
Treatment Approaches
The primary treatment strategy for PMP is a specialized two-part procedure known as Cytoreductive Surgery (CRS) combined with Hyperthermic Intraperitoneal Chemotherapy (HIPEC). CRS involves the meticulous surgical removal of all visible tumors and accumulated mucin from the abdominal cavity. This extensive surgery may include removing affected parts of organs like the peritoneum, spleen, gallbladder, and portions of the intestines. The goal of CRS is to leave behind no visible disease, or at least minimal residual tumor.
Immediately following CRS, while the patient is still in the operating room, HIPEC is administered. This involves circulating a heated chemotherapy solution directly within the abdominal cavity for a specific period, typically 60 to 120 minutes. The chemotherapy is heated to around 106-109 degrees Fahrenheit (41-43 degrees Celsius) to enhance its ability to penetrate tissues and destroy microscopic cancer cells. This direct application minimizes systemic side effects compared to traditional intravenous chemotherapy.
CRS and HIPEC is considered the most effective approach for PMP, offering a potential for long-term control. In some situations, systemic intravenous chemotherapy may be used, particularly for high-grade PMP or if the disease has spread more widely. However, systemic chemotherapy is a secondary therapy, as its effectiveness in PMP is less pronounced than CRS and HIPEC. This combined treatment requires specialized expertise and is performed at centers with experience in managing rare peritoneal surface malignancies.
Outlook and Follow-Up Care
The outlook for individuals with PMP is often favorable, particularly for low-grade cases that undergo complete CRS and HIPEC. PMP is a slow-growing cancer, and with comprehensive treatment, many patients experience long-term survival. Factors influencing prognosis include the tumor’s grade, with low-grade tumors having a better outlook than high-grade ones. The completeness of tumor removal during cytoreductive surgery also significantly impacts long-term outcomes.
Long-term follow-up care is important to monitor for any recurrence of the disease. This typically involves regular imaging scans, such as CT or MRI, to detect any new mucin accumulation or tumor growth. Blood tests to check tumor marker levels, like CEA and CA-125, are also part of ongoing surveillance. While PMP can be a persistent condition, effective management often allows individuals to maintain a good quality of life following treatment.