Good Doctor·Hyperthermic Perfusion | Hyperthermic Intraperitoneal Chemotherapy (HIPEC) for Pseudomyxoma Peritonei (PMP)

What is pseudomyxoma peritonei (PMP)?

PMP is a rare clinical syndrome primarily caused by the dissemination of mucinous tumor cells through peritoneal implantation, leading to the accumulation of mucinous ascites. Mucinous tumor cells can originate from virtually any intra-abdominal organ, with the appendix being the most common primary site; although the ovaries are frequently involved, such involvement is usually secondary. According to the literature, PMP arising from the appendix accounts for approximately 87.2% to 94% of all cases, with an annual incidence of about 2 per million.

What are the clinical manifestations of PMP?

The early symptoms of PMP are typically subtle and atypical, often presenting as abdominal distension and pain, gastrointestinal dysfunction, an abdominal mass, weight loss, or fatigue. These symptoms develop gradually as mucinous material slowly accumulates within the peritoneal cavity, making the condition prone to misdiagnosis as other diseases.

01. Abdominal distension, pain, or discomfort

In the early stages, patients often experience a dull, vague abdominal distension or ache, which may result from increased intra-abdominal pressure due to mucus secretion or from traction on the viscera. These symptoms can persist for months to years, gradually worsening, yet the pain is typically mild and easily overlooked.

02. Other gastrointestinal symptoms

Mucus accumulation may compress the intestines or impair digestive function, leading to decreased appetite, postprandial fullness, nausea, and changes in bowel habits, such as constipation or diarrhea.

03. Abdominal mass or lump

In a small number of patients, localized clustering of myxomas may be palpated as an ill-defined, firm or gelatinous mass in the abdomen; however, early-stage lesions are often small and deeply situated, making them difficult to detect. Patients may exhibit abdominal distension—resembling ascites—but the abdominal wall feels resilient upon palpation.

04. Weight Loss and Fatigue

Chronic malabsorption or tumor‑related catabolism may lead to gradual weight loss, accompanied by nonspecific systemic symptoms such as fatigue and anemia, which are often mistakenly attributed to fatigue or stress.

05. Abdominal CT Scan

Figure 1: Abdominal CT findings in pseudomyxoma peritonei (PMP). A large volume of fluid is seen within the abdominal cavity, with a density higher than that of pure water and comparable to soft tissue—typically exhibiting a CT value of approximately 10–30 HU, versus 0–10 HU for water alone. The intra-abdominal viscera, including the small and large intestines, demonstrate compression and displacement.

Differential diagnosis of PMP from other abdominal tumors

Progressive onset of symptoms: Early symptoms often recur and gradually worsen, but there are no signs of acute exacerbation. Lack of specificity: The clinical presentation resembles that of gastroenteritis, irritable bowel syndrome, ovarian tumors, and other conditions, necessitating confirmation through imaging studies (such as CT or MRI) or pathological biopsy. In women, gynecologic associations should be carefully considered: Female patients may experience lower abdominal distension or menstrual irregularities due to mucinous neoplasms or ovarian mucinous tumors, requiring differentiation from gynecologic disorders.

Treatment methods for PMP

Cytoreductive surgery (CRS) combined with hyperthermic intraperitoneal chemotherapy (HIPEC) is currently the internationally recognized standard treatment for peritoneal malignant mesothelioma (PMP). In the past, standalone CRS typically addressed only grossly visible lesions, resulting in high recurrence rates and short disease-free survival. By contrast, the combination of CRS and HIPEC leverages surgery, regional chemotherapy, thermal therapy, and large-volume fluid lavage to thoroughly remove and eradicate free cancer cells and microscopic tumor foci within the peritoneal cavity, thereby significantly improving clinical outcomes for PMP. The core advantage of CRS plus HIPEC lies in its ability to maximize tumor debulking: while CRS aims to excise all macroscopic tumors, HIPEC further eliminates microscopic tumor deposits that remain after surgery and are diffusely distributed, achieving maximal cytoreduction and effectively reducing recurrence while prolonging both overall survival and disease-free survival.

Figure 2: Appendiceal pseudomyxoma—Intraoperative hyperthermic intraperitoneal chemotherapy (GDHIPEC) treatment

Experts say

In the era before cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC)

PMP is considered a rare syndrome characterized by the accumulation of mucin throughout the peritoneal cavity, typically resulting from the rupture of an appendiceal mucinous neoplasm. Prior to the 1990s, treatment generally consisted of surgical interventions such as appendectomy or limited bowel resection; mucin evacuation; repeated mucinoma removal in cases of recurrence; and palliative procedures for intestinal obstruction or abdominal distension. However, because PMP is diffusely distributed throughout the entire abdominal cavity and surgery cannot completely eradicate microscopic foci, the rate of postoperative recurrence remains high, with an overall survival rate of only about 20%.

Conceptual shift: “Malignant tumors of the peritoneal surface” are a treatable, localized disease.

In the early 1990s, surgeons led by John Spratt and Paul Sugarbaker began to recognize that PMP is not “advanced cancer,” but rather a peritoneal surface malignancy that can be locally controlled. This conceptual shift was grounded in two major breakthroughs:

A. Cytoreductive Surgery (CRS): That is, to achieve the most complete removal possible of all macroscopically visible tumor lesions. This includes excising all macroscopically visible tumor foci and mucin; dissecting the peritoneum; and, when necessary, resecting the affected organs.

B. Hyperthermic Intraperitoneal Chemotherapy (HIPEC): This involves eradicating residual microscopic tumor foci after surgery. Although surgery can remove macroscopically visible mucinous tumors, minute lesions often remain. Consequently, surgeons have incorporated intraperitoneal chemotherapy into tumor resection to eliminate microscopic tumor deposits on the peritoneal surface; this approach later evolved into hyperthermic intraperitoneal chemotherapy (HIPEC), as heat enhances the tissue penetration of chemotherapeutic agents and increases their cytotoxicity.

Standardization of CRS Surgical Techniques

From the late 1990s to the early 21st century, peritoneal tumor surgeons led by Paul Sugarbaker established quantitative evaluation criteria for patient selection, surgical techniques, and treatment goals in CRS. Specifically, they used the Peritoneal Cancer Index (PCI) score to identify patients suitable for CRS, with the aim of achieving complete cytoreduction (CC‑0 or CC‑1).

HIPEC Equipment Optimization and Standardization of Clinical Application

As CRS surgical techniques have become standardized, HIPEC equipment and clinical applications have likewise undergone continuous refinement and standardization, aiming to achieve precise temperature and flow control, individualized selection of chemotherapeutic agents, and thorough eradication of free cancer cells and microscopic tumor foci. These efforts seek to reduce postoperative recurrence rates in peritoneal malignancies, prolong both overall survival and disease-free survival, and minimize perioperative and post‑HIPEC treatment toxicities.

CRS plus HIPEC is currently the treatment of choice for PMP, as recommended by experts.

Among peritoneal malignancies, PMP has been shown to be one of the conditions most suitable for combined CRS plus HIPEC therapy. CRS plus HIPEC significantly improves survival outcomes in PMP, with a median overall survival of up to 15–16 years, a 5-year survival rate of 60–90%, and a 10-year survival rate as high as 55% (Fu YB, et al. Int J Hyperthermia. 2025;42(1):2467296).

Expert Profile

Dr. Liu, M.D., Ph.D.

Professional Society Member:

• American Society for Cell Biology (2006–present)

• American Heart Association (2006–present)

• American Thoracic Society (1997–present)

• 2023–2025.5 Associate Professor, Division of Cardiology, University of Miami, USA

• 1999–2023 Assistant/Associate Professor, Division of Pulmonary and Critical Care Medicine, University of Nebraska Medical Center, USA

• 1996–1999 Postdoctoral Fellow, Division of Pulmonary and Critical Care Medicine, University of Nebraska Medical Center, USA

• 1992–1995: Master of Medicine, Department of Respiratory Medicine, Xijing Hospital, Fourth Military Medical University (under Professor Sun Bin)

• 1986–1992: Clinical Physician, Department of Respiratory Medicine, General Hospital of Shenyang Military Region

• 1981–1986 Bachelor of Medicine, Department of Clinical Medicine, Fourth Military Medical University