Surgery for peritoneal carcinomatosis

What is peritoneal carcinomatosis?

Peritoneal carcinomatosis occurs when tumor cells spread through the peritoneum, the membrane that lines the abdominal cavity and its organs. This spread can originate from different types of cancer, the most common being colorectal, gastric and ovarian cancer, peritoneal mesothelioma and appendiceal tumors such as pseudomyxoma peritonei.

It is an advanced condition, although not necessarily terminal. Today there are treatments with curative intent, especially when surgery is combined with HIPEC in cases of pseudomyxoma peritonei, peritoneal mesothelioma and ovarian cancer.

Symptoms of peritoneal carcinomatosis

Peritoneal carcinomatosis can present with progressive abdominal swelling, fluid build-up in the abdomen (ascites), diffuse abdominal pain or discomfort, early satiety, loss of appetite and weight, and changes in bowel transit that in advanced cases can lead to partial or complete obstruction. Severe tiredness is also a common symptom in these patients.

In many cases, symptoms appear during follow-up of a digestive or gynecological cancer that was already diagnosed. When they occur together, or when a check-up detects signs of new spread, it is advisable to see a team specialized in peritoneal oncology soon to assess the treatment options.

Causes and risk factors of peritoneal carcinomatosis

Peritoneal carcinomatosis is caused by tumor cells spreading from a primary tumor to the peritoneum. The most common origins are digestive tumors (colon, rectum, stomach, appendix and pancreas), gynecological tumors (mainly ovarian cancer), primary peritoneal mesothelioma and pseudomyxoma peritonei of appendiceal origin.

The risk of developing peritoneal carcinomatosis depends largely on the characteristics of the original tumor: involvement of the serosa, tumor perforation during the course of the disease or during surgery, and an advanced stage at initial diagnosis are factors that increase the likelihood of peritoneal spread. Knowing these factors helps guide oncological follow-up and detect peritoneal involvement earlier.

What the scientific evidence says about HIPEC

The PRODIGE 7 trial, led by Dr. François Quénet and published in The Lancet Oncology, compared cytoreductive surgery alone with cytoreduction plus short-course oxaliplatin HIPEC in patients with peritoneal metastases of colorectal origin. With that specific protocol, HIPEC did not increase overall survival and was associated with a higher rate of late postoperative complications.

The relevant reading of the study is not that surgery no longer makes sense, but the opposite: both groups exceeded 40 months of median survival, far above what would be expected with systemic treatment alone. What supports that result is complete cytoreduction, that is, the real ability to remove all visible disease. The surgical technique and patient selection weigh more than adding the perfusion.

An international analysis published in BJS Open in 2024, of more than 2,000 patients, found variable results between different HIPEC regimens, but its retrospective nature prevents concluding that any one of them is superior. That is why at Quenet-Torrent Institute HIPEC is not applied automatically: it is indicated according to the origin of the tumor, the protocol available, previous treatments and the board's assessment.

The peritoneal cancer index (PCI)

The peritoneal cancer index is the standard tool for measuring how much disease there is and where it is. It divides the abdomen into 13 regions and scores the size of the tumor implants in each one from 0 to 3, up to a maximum of 39 points.

A low score indicates more limited disease and therefore a greater likelihood of achieving complete cytoreduction. But no single figure automatically indicates or rules out surgery: the location of the implants can weigh as much as their number. A moderate PCI with diffuse involvement of the small bowel and its mesentery may be much less operable than a higher PCI concentrated in accessible areas.

It is also worth knowing that imaging tends to underestimate the real PCI, because millimeter-sized implants are not always visible. The final index is established in the operating room, during exploration.

How the case is studied before surgery

Before proposing surgery, the real extent of the disease needs to be estimated as precisely as possible. The workup is built in layers, adding tests only when they provide information that can change the decision.

The role of systemic chemotherapy

HIPEC does not replace intravenous chemotherapy. They are treatments with different ranges of action: HIPEC acts locally inside the abdominal cavity, while systemic treatment reaches the whole body, including any disease that may exist outside the peritoneum.

In most cases both are combined within the same strategy. Chemotherapy before surgery also shows how the disease behaves, which is in itself a selection criterion: a tumor that responds offers a very different surgical scenario from one that progresses despite treatment.

What is the life expectancy with carcinomatosis?

There is no single figure, and be wary of anyone who gives you one without having seen your case. The prognosis in peritoneal carcinomatosis depends mainly on three variables: the origin of the primary tumor, the extent of the disease measured by the PCI and, above all, whether or not complete cytoreduction is achieved.

That last factor is the one that changes the picture most. In well-selected patients in whom all visible disease can be removed, published results are far above those of systemic treatment alone, and cure can be achieved in around 20% of cases. In the PRODIGE 7 trial, with peritoneal disease of colorectal origin and complete cytoreduction, median survival exceeded 40 months in both groups of the study.

The origin of the tumor also makes important differences. Pseudomyxoma peritonei and peritoneal mesothelioma have the best long-term results; carcinomatosis of ovarian origin and colorectal origin are in an intermediate position; carcinomatosis of gastric origin is the most demanding in terms of selection.

Applying these figures to a specific case requires reviewing the tests, the histology and the previous course of the disease. That is exactly the purpose of a second opinion at a specialized unit.

Recovery and possible complications

Cytoreductive surgery with HIPEC is a high-complexity procedure, and explaining it openly is part of the treatment. The operation usually lasts between 6 and 12 hours in a single procedure.

Depending on the size of the procedure, the first hours may be spent in the intensive care unit. The hospital stay is, as a guide, between 7 and 14 days, although it depends on the extent of surgery and individual progress. After discharge, several weeks are usually needed to recover strength, appetite and the ability to carry out daily activities.

Like any major abdominal surgery, it carries risks that should be known: infection, bleeding, respiratory complications, thrombosis, changes in kidney function, delayed recovery of bowel transit, healing problems at the digestive joins and effects of the drugs used in HIPEC. The team's accumulated experience and case volume are consistently associated with lower rates of serious complications, but they do not eliminate them.

Follow-up after discharge includes checking healing, analyzing the final pathology results and deciding on subsequent systemic treatment.

What happens if surgery is not indicated?

The fact that complete cytoreduction is not feasible does not mean there is nothing to be done. It means the goal changes: from a potentially curative intent to control of the disease aimed at gaining time and quality of life.

In that scenario systemic treatment remains the core, and in selected cases PIPAC may be considered: chemotherapy given as a pressurized aerosol by laparoscopy, much less aggressive than cytoreductive surgery and repeatable over several sessions. It is especially useful for controlling ascites and the symptoms associated with peritoneal spread.

An initially unfavorable assessment is not always final. If the disease responds well to systemic treatment, a case can be reassessed and may become surgical.