What is a Peritoneal Surface Malignancy?

Peritoneal Surface Malignancy (PSM) means the presence of cancer cells on the peritoneum . Peritoneum is the membrane that lines the inner surface of the abdomen and envelopes several intra-abdominal organs – intestines, rectum, uterus,stomach, spleen etc.

PSM may arise from the peritoneum itself (primary peritoneal carcinomatosis); or it can spread from other organs to the peritoneum (secondary spread or metastases, which is more common).

Almost any cancer can spread to the peritoneum, but this is more commonly seen in tumors arising from abdominal organs like the stomach, large intestine (colon), ovaries and uterus. The tumor deposits can be as small as grains of sand, or can be large enough to be felt through the abdominal wall.

Which Cancers Usually Present as Psm?

Cancers which are associated with a high affinity to develop peritoneal metastases (PM) are colorectal cancer, ovarian cancer, gastric cancer, biliary tract cancers, pancreatic cancer and breast cancer.

How Do Cancers Reach the Peritoneum/ Peritoneal Cavity?

Once the cancer of an organ reaches its outermost layers, the cancer cells start shedding into the peritoneal cavity. Once in the peritoneal cavity these cells are carried by the flow of peritoneal fluid to other parts of the abdomen in a predictable manner.

These cancer cells establish adhesions to the peritoneum and develop as peritoneal metastasis. The size of this metastasis varies from microscopic to large nodules.

When Cancer Has Spread to the Peritoneum Is It the Last Stage or Stage 4?

Technically, it is indeed considered as stage 4 for most types of cancers except ovarian cancer, where it is considered as stage 3. However, it is important to realize that stage 4 covers a broad spectrum of disease spread.

For instance, cancer that has spread to peritoneum and cancer that has spread to bones or brain are considered stage 4. In the same line, regardless of the amount of cancer that has spread to peritoneum, all such spreads are categorized as stage 4.

However, limited PM can actually be treated with surgery to achieve excellent outcomes, even though technically it is stage 4.

How Was Psm Treated Traditionally?

The traditional approach to treat these malignancies was to give IV chemotherapy. However, IV Chemotherapy does not reach the peritoneal cavity in adequate concentrations to be effective, due to the inherent blood-peritoneal barrier.

What Is the Rationale Behind Crs and Hipec?

To tackle this drawback of traditional treatment strategies, the CRS+HIPEC protocol was developed. The first step of this treatment is Cytoreductive Surgery (CRS) that removes all of the visibly affected peritoneum and organs.

CRS is the cornerstone for a successful outcome. Once all visible disease has been removed by CRS, the remaining nonvisible microscopic disease is treated by HIPEC. This ensures that all the residual microscopic disease is destroyed and there is no residual disease within the abdomen.

What Does Cytoreductive Surgery (Crs) Involve?

It is a maximal effort surgery where all the visible peritoneal metastasis (PM) are removed. The procedure includes removal of involved peritoneum ,greater omentum and lesser omentum. Technically, the peritoneum covering the abdominal wall and diaphragms can be removed completely (total periental peritonectomy).

Since peritoneum also covers several organs (visceral peritoneum), and peritoneum cannot be stripped off of them, sometimes segments of small and large intestine, spleen, rectum may have to be removed to achieve complete tumour clearance. This is a necessary step before proceeding for HIPEC.

What Is Hipec?

HIPEC stands for Hyperthermic Intra Peritoneal Chemotherapy. It is a process where chemotherapy drugs are circulated inside the abdomen at high temperature for 60-90minutes.

A special HIPEC machine is used to deliver this heated chemotherapy at a sufficiently high flow rate to ensure even distribution of the chemotherapy and the heat within the abdominal cavity.

Studies done in the past have shown that chemotherapy agents of low molecular weight can diffuse across the tumour membrane to cause irreversible damage that finally kills the cancer cells.

It has also been shown that heat has a synergistic effect on some of these chemotherapy drugs, which means that the effect of chemotherapy given in the abdomen is magnified 100-fold by just heating these drugs to 42-43 degrees range.

This ensures an efficient cell kill. It is shown to decrease the recurrence rates and improve survival of patients suffering from several types of PSM.

Hipec – What Is the Aim of Rinsing the Abdominal Cavity With Heated Chemotherapy?

The rinsing of the abdominal cavity with heated chemotherapy aims to kill the microscopic tumor implants that are invisible to the naked eye, and that remain after removal of the visible tumor deposits by CRS.

If left untreated these cells get implanted at the operative site and the surrounding regions and produce a tumor recurrence. Destroying these tumor cells reduces the chances of the cancer coming back.

Are Crs and Hipec Done at the Same Time?

Yes. CRS and HIPEC are done in the same sitting. Once CRS is completed HIPEC is given.

Is Hipec Performed for All Who Undergo Crs?

Performing HIPEC is really demanding on the patient’s physiology. Hence it is performed only in situations which have proven benefit to the patient. Patients undergoing upfront CRS for ovarian cancers, colorectal cancers do not receive HIPEC after CRS.

Patient’s physiological condition at the end of Cytoreductive Surgery (CRS) also impacts the decision. Hence sometimes the decision to perform or not to perform HIPEC is taken during the surgery.