Tumors of the peritoneum

Pathology

The peritoneum is a thin serous membrane that lines the inner wall of the abdomen and surrounds many abdominal organs, such as the stomach, intestines, liver, and uterus. It has the function of protecting and holding these organs in place, as well as enabling their proper movement. Tumors of the peritoneum are a group of rare neoplasms that can have a primary or secondary origin.

Types

Primary forms arise directly in the peritoneum and are less common. Among these, the most frequent are:

  • peritoneal mesothelioma, which develops from mesothelial cells in the peritoneum;
  • primary carcinoma of the peritoneum, a tumor similar in histologic features to serous ovarian carcinoma but originating independently of the latter.

Much more common are secondary forms, also called peritoneal carcinosis, which result from the spread of cancer cells from other abdominal organs. The most common origins are cancers of the colorectum,ovary, stomach, and, more rarely, pancreas or liver.

Once considered a terminal condition treatable only with palliative care, peritoneal carcinosis is now recognized as a loco-regional disease that, in selected cases, can be treated with combined and potentially curative therapeutic approaches. Among these, cytoreductive surgery combined with hyperthermic intraperitoneal chemotherapy (HIPEC) represents one of the most innovative and promising strategies.

The numbers in Italy

According to data from the AIRTUM (Italian Association of Cancer Registries) Registry, primary tumors of the peritoneum are rare and account for less than 1% of all malignancies, while secondary forms are found more frequently in patients with advanced abdominal cancers.

Risk factors

Tumors of the peritoneum, in both primary and secondary forms, can be favored by several elements that increase the likelihood that the peritoneal membrane will be involved. The main recognized risk factors are summarized below:

  • previous advanced abdominal neoplasm: in particular, colorectal cancer, stomach cancer, ovarian cancer, or appendix cancer that have characteristics of local spread have a higher probability of developing peritoneal carcinosis;
  • exposure to asbestos: in the case of peritoneal mesothelioma, occupational or environmental exposure to asbestos is the main known risk factor for the occurrence of this primary cancer of the peritoneal membrane;
  • advanced age and female sex: some primary forms of the peritoneum, especially those similar to carcinoma of the ovary, affect women over 60 more frequently;
  • Genetic predisposition and family history: genetic mutations (e.g., of BRCA1, BRCA2 genes or those associated with Lynch syndrome) and a family history of ovarian, tubal, or peritoneal cancer increase the risk of peritoneal neoplasia;
  • Obesity and hormonal factors: in some primary forms of the peritoneum, factors such as obesity or history of hormone replacement therapy have also been identified as associated.

Symptoms

In the early stages, tumors of the peritoneum may not show obvious signs of disease. In fact, symptoms often appear at a more advanced stage, when the tumor has spread within the peritoneal cavity.

The most common disorders include:

  • presence of ascites, which is an accumulation of fluid in the abdomen that causes bloating and a sense of abdominal tightness;
  • Progressive increase in abdominal girth, unrelated to changes in body weight or diet;
  • Widespread or persistent abdominal pain, often described as a sense of heaviness or constant discomfort;
  • Alterations in alvus, such as constipation, diarrhea, or bowel irregularities;
  • breathing difficulties, due to the pressure exerted by the ascitic fluid on the diaphragm;
  • Loss of appetite and early sense of satiety, related to compression of internal organs.

Because these symptoms may also be common to other benign conditions, it is important not to be alarmed but to consult a specialist promptly in case of persistent or rapidly evolving complaints. A thorough medical evaluation allows for the determination of whether further diagnostic investigations are needed and, if disease is confirmed, for the initiation of an individualized course of treatment.

Diagnosis and examination

Diagnosis of peritoneal tumors requires a careful, multidisciplinary approach, as symptoms can be unspecific and similar to those of other abdominal conditions. The goal is to identify the presence of the disease early, assess its extent, and define the most appropriate course of treatment.

Level 1 examinations

The diagnostic course generally begins with a specialist examination and noninvasive imaging tests, which are useful in assessing the presence of ascites or abdominal masses:

    • Abdominal ultrasound

    • CT scan of abdomen and pelvis with contrast medium

    • Magnetic resonance imaging (MRI)

    • PET/TC

Second level examinations

When radiological examinations suggest the presence of peritoneal disease, it is necessary to obtain histological confirmation, that is, a microscopic diagnosis of the tumor cells.
This is done through:

    • diagnostic paracentesis

    • percutaneous or laparoscopic biopsy

Diagnostic laparoscopy

In many cases, diagnostic laparoscopy is a key step.
This is a minimally invasive procedure that allows direct observation of the peritoneal cavity, evaluation of the extent of disease, and taking samples for histologic examination. This examination also helps determine the resectability of the tumor, that is, whether the disease can be treated surgically.

Multidisciplinary assessment

All diagnostic findings are discussed within the Interdisciplinary Care Group (ICG).
This approach allows for a personalized treatment plan based on the biological characteristics of the tumor, the extent of the disease, and the patient’s general condition.

Therapies

After the diagnosis is confirmed, specialists in the multidisciplinary team evaluate a number of factors to plan an individualized course of treatment for the patient. In addition to the type of tumor, its size, and whether it has spread to other parts of the body, the patient’s age, general health status, and medical history are also considered. The treatment plan is then discussed with the patient, proposing alternative choices in case of equivalent effectiveness.

For selected patients with particularly aggressive cancers for whom standard therapies had not proven effective, there is also the possibility of receiving experimental therapies within clinical trials conducted by researchers at the Institute. In case this option is considered feasible by the multidisciplinary team, it will be proposed and explained to the patient with whom a shared decision will be made.

Surgery

Success in the treatment of peritoneal carcinosis depends on proper patient selection, high technical and surgical skills, and appropriate postoperative management . All these elements can only be guaranteed in a referral center specializing in the treatment of this specific form of the disease, such as our Institute.

Peritoneal carcinosis

Over the past 20 years, the treatment of peritoneal carcinosis has made important advances through the development of innovative surgical techniques and therapies. Today, this condition-once considered a terminal phase of the disease-can be addressed in a targeted manner and, in some cases, with curative intent.

The most effective and internationally recognized approach is the combined approach, which combines:

  • cytoreductive surgery, aimed at complete or nearly complete removal of visible disease;

  • intraperitoneal chemohyperthermia (HIPEC), a procedure that allows direct treatment of the abdominal cavity with heated chemotherapy drugs.

Cytoreductive surgery

The goal of surgery is to remove all macroscopic tumor implants from the peritoneum.
Because chemotherapy drugs penetrate only a few millimeters into the tissue, physical removal of the tumor is a critical step.

The intervention may include:

  • The removal of the primary tumor and nearby lymph nodes;

  • removal of organs involved in the disease, such as spleen, gallbladder, portions of the stomach or intestines, uterus and adnexa, depending on the spread.

When the disease affects the inner lining of the abdomen, peritonectomy, or partial or total removal of the peritoneum (pelvic, lateral, central, or diaphragmatic), is performed according to now standardized and internationally recognized techniques.
This surgery is performed only when a surgical field free of visible disease can be obtained.

Intraperitoneal chemoperthermia (HIPEC)

After the surgical phase is finished, HIPEC is performed in the same operating session.
During this procedure, the abdominal cavity is “washed” for about 60-90 minutes with a solution of chemotherapy drugs heated to 41-42°C.

Heat enhances the effectiveness of drugs and acts directly on residual cancer cells, damaging their internal structures and reducing the likelihood of recurrence.
Intraperitoneal administration also allows for very high drug concentrations (up to 1000 times higher than in blood) without increasing systemic toxicity.

HIPEC is particularly indicated for tumors that tend to remain confined to the abdominal cavity, such as ovarian, appendicular, and peritoneal tumors.

Pseudomyxoma Peritonei (PMP)

Pseudomyxoma Peritonei (PMP) is a rare form of mucinous neoplasm that originates in most cases from theappendix and, more rarely, from other organs such as the ovary, colon, or small intestine. It is characterized by the production and accumulation of mucin (mucus) within the abdominal cavity, which can result in a progressive increase in the volume of the abdomen and, in advanced cases, alterations in the function of internal organs.

In the past, the treatment of PMP relied on repeated debulking surgeries (i.e., partial removal of mucinous material and tumor masses), which unfortunately offered limited results: recurrences were very frequent and long-term survival was low, with 5-year survival rates around 6% and perioperative mortality of about 2.7%.

Thanks to advances in research and surgical techniques, today the combination of cytoreductive surgery and intraperitoneal chemohyperthermia (HIPEC) is the gold standard of treatment for this condition.
This approach, introduced and developed by U.S. surgeon Paul Sugarbaker, yields significantly better results: in specialized centers, 10-year survival rates can be as high as80 percent in selected cases.

Treatment of PMP requires a high degree of multidisciplinary expertise and must be performed in referral centers with the necessary skills and technologies to ensure maximum effectiveness and patient safety.

Peritoneal mesothelioma

Diffuse malignant peritoneal mesothelioma (DMPM) is a rare form of cancer that originates from the cells of the mesothelium, the thin lining that internally borders the abdominal cavity (peritoneum).
It is a disease mainly related to exposure to asbestos (asbestos) and, in recent years, its incidence has been steadily increasing, parallel to pleural mesothelioma.

DMPM is generally an unresponsive neoplasm to traditional systemic chemotherapy. However, in some cases, this type of treatment can help reduce the volume of disease, making the patient later a candidate for more radical surgery.

As early as 2006, the Consensus Conference of the Peritoneal Surface Oncology Group International (PSOGI) indicated the combination of cytoreductive surgery (CRS) and intraperitoneal chemoperthermia (HIPEC), possibly combined with systemic chemotherapy, as the standard of care for peritoneal mesothelioma.

The clinical progress achieved with this approach is significant: while the median survival with systemic chemotherapy alone was about 12 months, with combined CRS + HIPEC + systemic chemotherapy treatment, the results have more than quadrupled, reaching median survivals of more than 50 months in specialized centers.

Peritoneal carcinosis of colorectal origin

Peritoneal carcinosis of colorectal origin is a condition that can arise as an evolution of colon or rectal cancer, when cancer cells spread within the peritoneal cavity.

Thanks to new systemic treatment regimens and the possibility of combination treatments, the median survival of patients with this form is now significantly improved, reaching about 24 months. These data confirm that peritoneal spread represents a biologically distinct entity compared with other forms of colorectal cancer metastasis.

In carefully selected patients, the combination of cytoreductive surgery (CRS) and intraperitoneal chemohyperthermia (HIPEC) yielded even more encouraging results: a median survival of nearly 30 months and a disease-free interval of more than one year.

In light of this evidence, the Italian Association of Medical Oncology (AIOM) has included, already in the 2016 guidelines, the possibility of employing the combined CRS + HIPEC approach in patients with isolated peritoneal carcinosis, provided they are treated in specialized high-volume centers, with teams experienced in the management of this complex pathology.

Peritoneal carcinosis of ovarian origin

Epithelial ovarian carcinoma represents the most frequent and aggressive form among gynecologic malignancies. It is often referred to as a “silent tumor,” as in many cases it manifests with few initial symptoms and is diagnosed at an advanced stage (III or IV), when the disease has already spread to the peritoneum.

The standard treatment of advanced ovarian cancer is based on two basic pillars:

  • cytoreductive surgery, which aims to remove as much visible disease as possible;

  • systemic chemotherapy, to act on residual cancer cells.

The tendency of ovarian carcinoma to spread primarily in the peritoneal cavity has made this disease an ideal model for the use of locoregional treatments that can act directly on the site of disease.

In this context, the combination of cytoreductive surgery (CRS) and intraperitoneal chemohyperthermia (HIPEC) has shown promising results. Initially used mainly in cases of relapse, this strategy is now considered effective even at the time of initial diagnosis, as shown in recent international studies (Van Driel et al., N Engl J Med, 2018).

The combined approach allows, in selected patients treated in highly specialized centers, to significantly improve both overall survival and quality of life, offering new therapeutic perspectives even in the most advanced stages of the disease.

Chemotherapy

The treatment of peritoneal carcinosis is increasingly based on a multimodal approach, combining different therapeutic strategies to give patients the best chance of treatment.

In this context, systemic chemotherapy can be used:

  • before surgery (in the neoadjuvant phase), to reduce the extent of disease and increase the chance of complete cytoreductive surgery;
  • after surgery (in the adjuvant phase), to decrease the risk of recurrence and prevent the spread of disease outside the peritoneum.

In recent years, the development of increasingly targeted and effective drugs has helped improve the outcomes of these treatments, making a more personalized approach possible. However, there are still no standardized treatment protocols in terms of number of cycles, timing and drug combinations, as each case must be evaluated individually.

For this reason, it is essential that each patient be taken care of by an Interdisciplinary Care Group (ICG) dedicated to the specific disease. This multidisciplinary team-composed of oncologists, surgeons, radiation oncologists, and other specialists-assesses the clinical situation collegially, defines an individualized course of care, and accompanies the patient through all phases of treatment, ensuring continuity, safety, and shared decision-making.

Supportive therapies

Patients with peritoneal carcinosis are supported throughout their diagnostic-therapeutic journey by specialists in palliative care, food and nutrition, and psycho-oncology.

Ongoing support

At the Candiolo Institute, the doctors and nurses of the multidisciplinary team are available to provide the patient with all the support he or she needs to manage the various side effects he or she will face in the course of treatment.

Direct line to specialists

The cancer patient is often a fragile patient, who needs help and support in his or her disease journey: when he or she experiences an ailment, whether related to the disease or a side effect of therapy, he or she should be able to receive a specialist’s opinion quickly, through a “fast track.”

For this reason, at the Candiolo Institute there is an assistance service every day, Monday through Friday from 8 a.m. to 5 p.m.: just call the secretary of the Oncology Day Hospital (011.993.3775 ) reporting the need for an urgent consultation, and the patient is quickly contacted by his or her specialist doctor.

Continuing care and palliative care

At the Candiolo Institute, specialists from different disciplines are available at Candiolo for patients who need or request them to offer:

    • nutritional support

    • psychological support

    • physiotherapy

    • dressing of venous access devices

    • pain therapy

    • Management of other coexisting conditions.

Social work

Social work

The Social Service Department of the Candiolo Institute conducts information and orientation interviews for patients and their families on how to access services in the area and how to obtain welfare and social security benefits provided by law (disability, benefits for aids and prostheses, work leave, etc.).

The service operates on Wednesdays and Fridays from 9 a.m. to 1 p.m. – Phone: 011.993.30

Follow up

With the conclusion of the course of treatment, the follow-up period begins during which, through a series of examinations and visits, the side effects of the therapies performed, their effectiveness, and the patient’s functional recovery are monitored.

Follow-up examinations are especially important to intercept any recurrences early so that appropriate therapy can be intervened. For the patient, they are also a valuable opportunity for dialogue with their medical specialist.

It is the same specialist physician who schedules follow-up visits, in which the patient’s health condition is assessed and the required test reports are viewed.

Checkups are performed at scheduled intervals for the duration of 5-10 years and include examination, blood chemistry tests, CEA marker assay, Ca19.9, and CT chest and abdomen with contrast medium.

They have a shorter cadence at first (three to six months), then gradually thin out over time (once a year). The frequency and type of examinations provided depend on the stage of the tumor and the treatments given.

Interdisciplinary Group

Every cancer requires, in all phases of disease management, a multidisciplinary approach that at the Candiolo Institute is guaranteed by a team of different specialists, belonging to the various clinical and surgical departments of the Institute: this team is called GIC (Interdisciplinary Care Group). The GIC ensures that each patient is taken care of throughout the diagnostic-therapeutic process, including prescribing and booking examinations and communicating with the patient and his or her family members. The GIC defines and shares a personalized care pathway for each patient, based not only on the type and stage of the tumor, but also on the patient’s own characteristics. The goal is to ensure that he or she has the best outcome both oncologically and functionally and the maintenance of a good quality of life.The Group also works closely with researchers at the Institute to ensure that patients have rapid access to the latest research-produced innovations in screening, diagnosis and treatment.

Clinical divisions

The diagnostic and therapeutic pathway of peritoneal tumors or Candiolo involves several clinical divisions, including:

Why choose us

At Candiolo IRCCS Institute, every pancreatic cancer patient is followed in a highly specialized manner, thanks to the synergistic work of a dedicated Interdisciplinary Care Group (ICG).

Clinical experience and tailored approach

Due to the high number of cases treated each year, the Candiolo Institute is a national reference for taking pancreatic cancers. Our experience enables us to deal with even the most complex situations, always with a personalized approach built on the clinical and personal profile of each patient.

Imaging technologies and advanced diagnostics

Establishing the treatment plan always starts with an accurate and timely diagnosis. Patients have access to state-of-the-art imaging technologies that allow accurate assessment of the extent of the disease.

In addition, the Institute offers advanced and sophisticated laboratory investigations, including molecular and genomic analyses, which are critical for identifying biological features of cancer and guiding therapeutic decisions

Minimally invasive surgical techniques and multidisciplinarity

When indicated, surgery is performed with minimally invasive techniques (laparoscopic or thoracoscopic), which reduce operative trauma, promote faster recovery, and improve postoperative quality of life. Every treatment choice is defined within the GIC, ensuring a consistent and integrated approach.

Clinical research and access to trials

As an IRCCS, the Candiolo Institute combines clinical practice with a strong vocation for scientific research. Patients can be evaluated forinclusion in active clinical trials, which represent a real chance to access innovative therapies not yet available in standard practice. Collaboration between care and research is a distinctive value that translates into concrete opportunities for the patient.

Care and support every step of the way

The Interdisciplinary Care Group takes care of the person at every stage: from diagnosis to treatment to follow-up, with attention to nutritional support, psychological health, and reintegration into daily life. The organization of checkups, visits and treatment is designed to ensure continuity and serenity, always valuing the human dimension of care.