Peritonectomy

Peritonectomy, also known as cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC), has gained widespread acceptance as an effective treatment for peritoneal metastases (PM) from a variety of malignancies. However, this is a complicated treatment that is difficult to perform, and effective outcomes require a careful patient choice. The purpose of cytoreductive surgery is to completely remove all macroscopic diseases. Peritonectomy operations and en-bloc excision of the viscera are used to accomplish this. The extent to which they are used is determined by the amount of PM. Only the diseased peritoneum is removed, not the normal peritoneum.

Patterns of Peritoneal Cancer Spread

Treatment for PM necessitates an understanding of the causes and mechanisms of peritoneal cancer spread. The parietal peritoneum, which lines the abdominal wall, and the visceral peritoneum, which covers the abdominal and pelvic organs, make up the peritoneum. As it surrounds the visceral organs, it reflects and folds, perhaps creating voids between its lining along the abdominal and pelvic walls.

The network of reflections, folds, borders, and potential niches in the peritoneal cavity and between the peritoneal and retroperitoneal spaces provides a conduit for disease to spread inside the peritoneal cavity and between the peritoneal and retroperitoneal spaces. PM is produced by a primary tumor emerging elsewhere. Primary tumors developing from the peritoneum are uncommon, and malignancy disseminated to the peritoneum is the most common cause of PM. Peritoneal carcinoma can spread in four different ways.

1. Direct spread First, tumors can travel from one organ to another directly through the serosa. Tumors of the stomach, colon, and pancreas spread to adjacent and non-adjacent organs in this way.
2. Tumors can also spread through the subperitoneal lymphatic vessels, which run along the ligaments, mesenteries, and omenta, from one noncontagious organ to another. This pattern of dissemination is shown in lymphomas, especially non-Hodgkin's and accounts for a small proportion of PM.
3. Pseudomyxoma peritonei and ovarian cancer have this redistribution tendency along with the flow of ascitic fluid. The cancer cells follow the intraperitoneal fluid flow. The fluid in the pelvis collects due to gravity. The downward migration of the fluid via the paracolic gutter to the subdiaphragmatic area, where it is transferred via the falciform ligament to the lesser and larger omenta and along the intestinal surfaces, is caused by the negative pressure induced by respiratory activity. The pelvis, the lower end of the small bowel mesentery, the right paracolic gutter, the recessions of the diaphragm, and the larger and lesser omenta are the most prevalent PM locations. PM also tends to engage the visceral peritoneum in higher volumes at three specific locations where the intestine is attached to the retroperitoneum. The rectosigmoid colon, where it comes from the pelvis (this site is also dependent and is more frequently strongly involved), the ileocecal valve area, and the pylorus zone are the three. The continual peristaltic action is responsible for small bowel sparing.
4. Hematogenous route: Both intra- and extra-abdominal malignancies, as well as PM originating from breast cancer, lung cancer, and melanoma, use this path to disseminate.

Basic Principles

Peritonectomy and visceral resections are included in CRS. The goal is to eliminate all macroscopic pathology, leaving no residual disease or, in some cases, the disease that is less than 2.5 mm in sizes, such as pseudomyxoma peritonei or peritoneal mesothelioma. The reasoning behind this is because that intraperitoneal chemotherapy is ineffective in the treatment of tumor nodules larger than 2.5 mm in diameter. CRS is used to treat macroscopic disease, whereas HIPEC is used to treat microscopic disease.​ It is possible that complete tumor removal will involve the removal of neighboring viscera. A complete pelvic peritonectomy, for example, often entails the removal of the pelvic sidewalls, the peritoneum overlying the urinary bladder, the cul-de-sac, and excision of the rectosigmoid, with or without a pan-hysterectomy. To perform a thorough resection, metastases in the area of the ileocecal valve may demand the removal of the terminal ileum and a small portion of the right colon. The tumor flowing in from the foramen of Winslow and sometimes the tumor affecting the lesser omentum are frequently confluent with a disease in the sub-pyloric region. To accomplish full cytoreduction, a distal or total gastrectomy may be required. En-bloc peritonectomy and a section of the intestine may be required if cancer layers on the peritoneal surface and a portion of the intestine.

Patient Selection for Peritonectomy

Morbidity and mortality have been the most common criticisms of CRS and HIPEC. Extensive CRS is not beneficial to all patients. In individuals with advanced disease, rapid recurrence of peritoneal metastases with or without lymph node or systemic metastases occurs, causing morbidity without improving survival. To quantify the results of CRS and HIPEC, quantitative prognostic factors have been created, and these should be considered when selecting patients for the treatment. Histopathology, imaging findings, the peritoneal cancer index (PCI), and the adequacy of the cytoreduction score are the indicators. These factors, in addition to the patient's overall fitness and health for the procedure, should be considered before a patient is scheduled for surgery. Every patient should be evaluated by a multidisciplinary team that includes a surgeon, a medical oncologist, and other related specialists.

Histopathology

The grade of the tumor has an effect on the outcome of appendiceal tumors and pseudomyxoma peritonei, regardless of how complete the cytoreduction is. Low-grade cancers do better than high-grade cancers and signet ring cell cancers. Patients with advanced disease benefit from combined modality treatment as well. Other GI malignancies, such as colorectal cancer and gastric cancer, have a smaller impact on survival according to histologic subtype. Histopathology has a big role in peritoneal mesothelioma survival, with epithelioid subtypes faring better than biphasic or sarcomatoid subtypes.

Imaging Studies

The usual study for assessing patients prior to surgery is a contrast-enhanced CT scan of the thorax, abdomen, and pelvis. It can rule out significant distant metastases and anticipate disease severity. Helical CT was reported to have a sensitivity of just 20–50% for peritoneal cancers less than 1 cm, compared to 84–95% for bigger tumor deposits. Esquivel et al. discovered that the preoperative CT PCI score underestimated the amount of carcinomatosis in 34% of patients in multi-institutional research. Some authors have shown that MRI is more reliable for detecting 1 cm nodules in recent investigations, whereas others have found no difference. The interpreter's knowledge is also important in MRI results. Extra-abdominal (mediastinal or supraclavicular) lymphadenopathy can be detected using PET or PET-CT scans, which can provide more information in this direction. However, when it comes to determining the amount and distribution of peritoneal cancer, PET or PET-CT scans provide no more information than a typical, high-quality CT scan. Patients with resectable mucinous carcinomatosis may be distinguished from those with non-resectable carcinoma using a CT scan with two distinct radiographic criteria (segmental blockage of the small bowel and presence of tumor nodules greater than 5 cm in diameter on small bowel surfaces or directly next to small bowel mesentery). However, CT scan sensitivity for malignant nodules smaller than 5 mm, particularly on small intestinal surfaces, remains low.

Peritonectomy Contraindications

CRS and HIPEC are major surgeries that require the patient to be in good health and to have all other systemic disorders (cardiac, pulmonary, and other.) under control. The surgery would be ruled out if any of these conditions were present. If the patient is fit to withstand major surgery under general anesthesia, age is not an absolute contraindication to the combination treatment, though surgical efforts and chemotherapy doses may need to be adjusted. As previously mentioned, there are disease-specific contraindications. For example, a predicted PCI of >17–20 for colon cancer and >12 for stomach cancer would exclude a curative surgery. Growth on neoadjuvant therapy is not a contraindication to CRS and HIPEC in patients with colon cancer and ovarian cancer. Involvement in the urinary tract is not an absolute contraindication if tumor tissue clearance can be achieved and the surgery does not increase morbidity. Multiple extra-abdominal metastases or involvement of the suprarenal retroperitoneal lymph nodes is a strict contraindication. Except for colon carcinomatosis, liver metastases may be a contraindication. Several investigations have found that the presence of a few liver metastases had no effect on mortality when they were surgically removed for PC from colon cancer. The contraindications for PCI in situations when there is no cut-off are as follows:

• Massive bowel removal that is likely to impair future quality of life, such as 2 or more sites of segmental small intestine blockage, patients necessitating a total gastrectomy combined with a total colectomy
• Pancreas head, bladder trigone, and porta hepatis are all involved.
• Pleural space invasion, either extensive or diffuse.

Techniques of Peritonectomy and HIPEC

It is critical for a surgeon working with PSM to obtain the appropriate technical abilities and be adept in electrosurgery dissection. High-voltage electrosurgery leaves a thermal necrosis margin that is devoid of live cancer cells. Traditional scissor and knife dissections will unnecessarily disperse a high number of tumor cells throughout the abdomen during peritonectomies and visceral resections. This reduces the risk of long-term disease and hemorrhage, both of which are critical in these lengthy procedures. Furthermore, hemostasis must be complete before beginning the HIPEC procedure, as no hemostasis can be achieved during that time, and if there is continued bleeding, the procedure may need to be terminated. Ball-tip electrocautery, first described by Dr. Sugarbaker, is the most common method of dissection. Several doctors, however, have preferences for bipolar scissors, ultrasonic scalpels, or a combination of any of the abovementioned.

Patient Positioning and Gaining Access

To provide complete access to the perineum, the patient is put in a supine posture with the gluteal fold at the end of the table. To avoid pressure points and myonecrosis of the calf muscles, modified lithotomy or a leg-split posture is employed with extreme caution. The skin is prepared from the mid-chest to the mid-thigh, as well as the genitalia and catheterization.

A midline cut from the xiphoid to the pubis is used to open the abdominal cavity. The old abdominal cut, as well as the umbilicus, are frequently removed. Because these patients have typically had previous surgery, extreme caution is required when opening the abdomen to avoid injuring the intestines. A self-retaining retractor device is required for adequate abdominal exposure.

Pre-operative imaging or laparoscopy can usually provide a roadmap for the stages involved in the procedure. If diaphragmatic stripping is required, a xiphoidectomy will aid in better exposure and retractor blade placement. When the disease is advanced, a thorough examination is carried out to rule out any contraindications to CRS, and no bowel should be resected until the surgical approach is completed.

Anterolateral Partial Peritonectomy

An extra-peritoneal technique may assist dissection and save time if an anterolateral parietal peritonectomy is planned based on preoperative imaging or laparoscopy. This extra-peritoneal dissection can be extended into the upper abdomen and then into the sub-diaphragmatic plane for diaphragmatic peritonectomy. Once a portion of the peritoneum along the costal margin has been dissected away from the diaphragmatic muscles, the costal retractor blades can be used to raise the parities, making dissection much easier. It's a good idea to make a tiny opening in the peritoneum at this point to palpate the peritoneal surface. An extra-peritoneal method can be used to perform a bilateral anterolateral parietal peritonectomy if there are significant deposits over the anterior parietal peritoneum.

It is critical to maintain steady traction on the abdominal wall and the specimen during this technique in order to reveal the planes, where a high-voltage electrocautery current is used to dissect the parities' peritoneum. When the dissection reaches the paracolic area, it rotates medially, aided by the colon's medial tension, and the dissection can continue in the plane of the Toldt fascia. This dissection can be incorporated into the right and left subphrenic peritonectomy, and it can also be continued inferiorly into the complete pelvic peritonectomy.

Right Subphrenic Peritonectomy

The diaphragmatic muscle is brought into the vision of the abdominal cut by firm traction on the peritoneal specimen, and the plane revealed is subsequently dissected to advance with the subphrenic peritonectomy. To prevent blood loss, several tiny arteries connecting the diaphragmatic muscles and the peritoneum must be coagulated. Just before the tendinous section of the diaphragm, the diaphragmatic vessels will be met, and they should be retained if feasible. Tumor deposits may be infiltrative and involve the diaphragmatic muscle in invasive diseases, particularly in the region of the tendinous section. This may necessitate the removal of a portion of the diaphragm, which can be sutured with a non-absorbable monofilament suture in a continuous or interrupted fashion. This suturing might be done right away or delayed until after the HIPEC to allow the chemotherapy to flow throughout the chest. Injury to the right hepatic vein and the IVC must be avoided at all costs. The dissection continues posteriorly over the top half of the Gerota fascia and the adrenal, which form the dissections' base.

The diaphragmatic peritoneum turns onto and becomes continuous with the Glisson's capsule once the bare portion of the liver is met superiorly. Heavy pathology over the liver, which can create a thick layer over the Glisson's capsule, is frequent in disorders like pseudomyxoma peritonei. Glehen et al. have developed a highly effective treatment for this condition. The sub-Glissonian space is penetrated using either sharp or electrocautery and then the Glisson's capsule, together with the disease, is effectively and quickly pulled off the liver surface by sharply moving the fingers in this plane. If the tumor sample is kept intact, this dissection is substantially aided. Electro-vaporization or dissection can be used to remove isolated tumor deposits.

Homeostasis can be established by covering the liver surface with a surgical pad while the dissection continues to another part of the abdomen. This component of the dissection should be planned earlier in the cytoreduction to ensure ample time for hemostasis. The dissection continues to the right, where the perirenal fat and the adrenal are encountered. There is a danger of traumatizing the vena cava or the caudate lobe veins that run between the vena cava and segment 1 of the liver because the peritoneal reflections at the posterior aspect of the liver are divided. Injury to these tissues, which might result in substantial bleeding, should be avoided.

Left Subphrenic Peritonectomy

The epigastric fat and peritoneum at the margin of the abdominal incision are pulled taut and the posterior rectus muscle is dissected, with the diaphragmatic muscle visible as the dissection progresses cephalad in the left upper quadrant. The peritoneum is separated from the entire diaphragmatic surface, the left adrenal, and the superior half of the perirenal fat by proceeding posterolaterally. By splitting the peritoneum along the Toldt's line, the splenic flexure of the colon is severed from the left parabolic gutter and retracted medially. To guarantee minimal blood loss and adequate hemostasis, the majority of the dissection must be done with electrosurgery.

Resection of Contiguous Structures and Viscera

Full Thickness Diaphragmatic Resection

When the diaphragmatic muscle is infiltrated by tumor, a complete thickness resection is required. Bipolar scissors, electrocautery, or Mayo scissors can be used for this. Before a subphrenic peritonectomy, the total vascular management of the hepatic vessels should be obtained when the lesion is adjacent to the vascular structures on the right side.

Rectosigmoid Colon Resection

To achieve full cytoreduction, removal of the rectosigmoid colon is frequently required. When a rectosigmoid removal was not done with a pelvic peritonectomy, 74 percent of patients with advanced ovarian cancer with possible rectal serosal involvement had residual pathology, according to Hertel et al. Several studies have demonstrated that it does not worsen the morbidity of CRS and that a diverting ileostomy is not required in all patients. An ileostomy can be avoided if 12–15 cm of the rectum is retained. The technique of reversing the stapled anastomosis with a layer of interrupted silk sutures has been reported by Dr. Sugarbaker. When performing a stapled anastomosis on a female, remember to avoid the left ureter and the vaginal stump.

Partial/total Gastrectomy

A total or partial gastrectomy may be required if there is a tumor surrounding the stomach or if the left gastric artery is involved. Sugarbaker employed a phased technique to drain the intestinal secretions, which included a high jejunostomy followed by a Roux-en-Y anastomosis a few months later. Recent investigations have shown that fast recovery of gastrointestinal continuity is possible and safe in experienced centers.

Colectomy, Distal Pancreatectomy, and Hepatic Resection

In individuals with significant omental deposits or bowel surface/mesenteric deposits, removal of the right or transverse colon is frequently required. A whole or subtotal colectomy may be limited to cases of more advanced cancer. In patients with pseudomyxoma peritonei, a right hemicolectomy may not be required to treat an appendiceal primary. Patients who have distal pancreas involvement with or without splenic hilar invasion, pancreatic capsule involvement, or iatrogenic damage may require a distal pancreatectomy. This treatment has been demonstrated to be safe when performed as part of CRS and HIPEC in experienced centers; while it increases morbidity, it does not increase death. The morbidity induced by a pancreatic fistula in ovarian cancer patients may cause a delay in initiating adjuvant treatment. In patients with significant deposits on the liver wall, non-anatomical liver resection may be indicated. CRS can be used to accomplish synchronous excision of intraparenchymal liver metastases in ovarian cancer patients, especially in those with single liver metastases.

Conclusion

Peritonectomy is a difficult treatment with a lengthy learning curve. A surgeon performing a peritonectomy must be experienced operating on all sections of the abdomen cavity and have a thorough understanding of the anatomy of each location. The choice of patients is just as crucial as the technical skill necessary for this treatment. Collaboration and a multidisciplinary approach are also necessary for achieving the best results: possibly curative treatments with low postoperative mortality and morbidity, and appropriate long-term quality of life impact.