Retroperitoneal Cancer

Retroperitoneal cancer is a rare group of tumors that develop in the back of the abdomen, often growing silently to very large sizes before they are discovered. Understanding this uncommon disease and finding expert care can make a critical difference in treatment outcomes.

Table of contents

• What is Retroperitoneal Cancer?
• Types of Retroperitoneal Cancer
• Risk Factors
• Symptoms
• Diagnosis
• Treatment
• Multidisciplinary Care

What is Retroperitoneal Cancer?

Retroperitoneal cancer is a rare group of tumors that occur in the retroperitoneum, which is the space in the back of the abdomen, between the lining of the abdominal cavity and the back abdominal wall^[1]. This area contains important organs including the kidneys, pancreas, and major blood vessels like the aorta and vena cava^[1].

These tumors are quite uncommon. Approximately 15 percent of soft tissue sarcomas arise in the retroperitoneum, and sarcomas make up about one third of all malignant tumors that develop in this location^[1][3]. In the United States, approximately 8,600 new cases of soft tissue sarcoma are diagnosed annually, representing less than one percent of all newly diagnosed cancers^[1]. In England and Wales, retroperitoneal sarcomas are expected to compose approximately 15% of the 2,000 cases of soft tissue sarcomas each year, with an estimated 250 to 300 new diagnoses annually in the UK^[3].

One of the challenges with retroperitoneal tumors is that they often grow slowly and can reach very large sizes before they are detected. Retroperitoneal sarcomas can grow to 20 to 30 centimeters, and about 50% are larger than 20 cm at the time of diagnosis^[2][6]. Tumors smaller than five centimeters are rarely seen because patients do not notice them until they have grown much larger^[1].

Types of Retroperitoneal Cancer

The two most common types of retroperitoneal cancer are liposarcoma, which originates in fat cells, and leiomyosarcoma, which originates in smooth muscle tissue^[2][4].

Liposarcoma is most common in middle-aged men between the ages of 50 and 65^[2]. Patients with liposarcoma can have slow growing tumors that don’t spread, or tumors that grow rapidly and aggressively spread to other organs. There are five subtypes of liposarcoma: well differentiated, dedifferentiated, myxoid, round cell, and pleomorphic^[2].

Leiomyosarcoma is a form of soft tissue sarcoma that accounts for about seven to 11 percent of all cases of soft tissue sarcoma. This cancer can occur in both men and women and is more common in adults than in children or adolescents^[2].

Other less common types of retroperitoneal cancer include solitary fibrous tumor, pleomorphic sarcoma, malignant nerve sheath tumor, synovial sarcoma, and Ewing’s sarcoma^[2][4].

Risk Factors

A risk factor is anything that increases your chance of getting a disease. Having a risk factor does not mean that you will get cancer, and not having risk factors doesn’t mean that you will not get cancer^[1].

At this time, the exact cause of retroperitoneal sarcomas is unclear. Research suggests that abnormalities in DNA can lead to abnormal genetic changes and the growth of cancerous cells^[2]. Some cases appear to be “bad luck” with no clear link to genetics or lifestyle^[14].

Risk factors for retroperitoneal sarcoma include several inherited disorders^[1][2]:

• Li-Fraumeni syndrome
• Familial adenomatous polyposis (FAP; Gardner syndrome)
• Neurofibromatosis type 1 (NF1; von Recklinghausen disease)
• Tuberous sclerosis (Bourneville disease)
• Werner syndrome (adult progeria)
• Nevoid basal cell carcinoma syndrome (Gorlin syndrome)
• Hereditary retinoblastoma

Other risk factors may include^[2]:

• Prior radiation exposure from previous radiation treatment
• Damage to the lymph system
• Family history of cancer
• Long-term exposure to certain toxic chemicals such as vinyl chloride, herbicides, arsenic, and dioxin

Symptoms

Retroperitoneal sarcomas can be difficult to diagnose in their early stages due to their location and the absence of specific symptoms, despite reaching large sizes^[5]. These tumors usually present late and often are not noticed by the patient until they have become larger in size^[1][3].

Retroperitoneal sarcomas most commonly present as an abdominal mass, often without other symptoms^[1]. Although the median patient age is approximately fifty years, retroperitoneal sarcomas can occur at any age and arise equally in women and men^[1]. The early stages of this cancer may be asymptomatic, meaning there are no symptoms^[2].

When symptoms are present, they relate to the mass effect of the tumor or to local invasion of surrounding structures^[1]. Symptoms of retroperitoneal cancer can vary depending on the size and location of the tumor and may include^[1][2][4]:

• A noticeable lump or mass in the abdomen
• Abdominal swelling or increase in abdominal size
• Abdominal pain or dull pain in the abdomen or back
• Loss of appetite or weight loss
• Early satiety (feeling full after eating only a small amount)
• Blood in stools
• Lower extremity swelling
• Constipation
• Nausea and vomiting

Leiomyosarcoma tumors may cause bleeding in the gastrointestinal tract and lead to black, tarry, foul-smelling stools, abdominal discomfort, and even vomiting of blood^[2].

Patients who notice any of these signs should schedule an appointment with their doctor^[2].

Diagnosis

A diagnosis of retroperitoneal sarcoma may start with a visit to your doctor, who will then refer you to a specialist^[4]. Some retroperitoneal sarcomas are discovered through investigations for another medical condition or are diagnosed after surgery for a different problem^[4]. Often, discovery of these tumors is an incidental finding^[5].

Your symptoms will be investigated using a series of tests that may identify sarcoma. Tests may include^[4]:

• Physical examination – looking at and feeling any lump
• A scan – taking pictures of the inside of the body
• A biopsy – taking and testing a tissue sample

Computed tomography scan (CT-scan) is the most useful diagnostic tool for retroperitoneal sarcoma^[1]. This imaging provides good visualization of the tumor and its relationship with adjacent organs and their potential involvement^[3]. A CT scan of the chest is often sufficient to complete staging, which means determining if cancer cells have spread to other parts of the body^[3].

Magnetic resonance imaging (MRI) can be used in patients with allergies to intravenous contrast as well as in cases where an assessment of spinal structures, nerves, and muscles is necessary^[3].

Tissue diagnosis prior to initiating treatment is important^[3]. Image-guided, percutaneous core needle biopsy uses a hollow needle to remove tissue samples^[11]. Core needle biopsies can help tell the difference between a sarcoma and other conditions occurring in the abdomen and can help decide the correct treatment^[4]. A clear diagnosis will be made after a pathologist with experience of sarcoma has examined the tissue sample^[4].

Treatment

Surgery is the primary treatment for retroperitoneal sarcoma and the only potential curative treatment^[1][2][3]. Complete surgical resection with negative margins remains the cornerstone of treatment and is the only chance for cure^[11]. The quality of the first surgical intervention performed after diagnosis depends on the evolution and the best possible survival rates, as well as the reduction of recurrences^[5].

The surgeon will remove the tumor and will aim to take out an area of normal tissue around it when possible. This is known as taking a margin^[4]. In order to achieve negative margins, multivisceral en bloc resection, meaning removal of the tumor along with any organs next to it as a whole, is often necessary^[4][11].

Because of how large these tumors can be, they may touch, compress, displace, or invade major organs and blood vessels^[2]. Depending on the size and location of the tumor, surgery may require removal of part of or whole organs such as the kidney, colon (bowel), pancreas, spleen, or bladder, which can have implications on quality of life^[4]. A small number of people will need a colostomy or urostomy following surgery^[4].

Surgery typically requires the efforts of multiple teams to carefully remove the tumors, multiple organs, and even major blood vessels. As a result, surgery can last for eight hours or more and demand significant physical and mental energy^[2].

In cases where it is not possible to remove the tumors completely, surgery is unlikely to be recommended^[4].

Patients may also undergo radiation and or chemotherapy^[2]. Neoadjuvant therapies (chemotherapy, external beam radiation, or combination radiation and chemotherapy) given before surgery are safe in well-selected patients and may be considered after careful review by a multidisciplinary sarcoma tumor board when the recurrence risk is high^[11]. However, there is currently insufficient evidence to determine if these nonsurgical treatments are effective^[2].

It is highly likely that the cancer will return and require additional surgery, which is usually more complex and with greater risk than the previous surgery^[2]. The ability completely to resect a retroperitoneal sarcoma and tumor grade remain the most important predictors of local recurrence and disease-specific survival^[3].

Multidisciplinary Care

The evaluation and treatment of retroperitoneal sarcomas are challenging because these tumors are relatively rare and frequently present with advanced disease in an anatomically complex location^[1]. This is why it is essential to have an interdisciplinary team with the experience to carry out each intervention correctly^[5].

Complete surgical resection is best performed in high-volume centers by a multidisciplinary sarcoma team^[3]. The treatment team includes surgical oncologists, medical and radiation oncologists, plastic surgeons, vascular surgeons, nutritionists, pathologists, traumatologists, interventional radiologists, nuclear medicine specialists, radiologists, nurses, and anesthesiologists^[1][5].

If you are being told by anyone that this is something that cannot be taken care of from a surgical standpoint, you really need to get in to see someone who specializes in this disease, because your first operation is your best bet for a cure, so you want to make sure it’s done right^[13].

Careful monitoring and the involvement of an experienced surgical oncologist are important to the successful outcome for patients with retroperitoneal sarcoma^[1].