Sarcoma is a rare cancer that develops in the connective tissues: muscle, bone, nerves, cartilage, tendons, blood vessels and the fatty and fibrous tissues.

Retroperitoneal sarcomas occur in the retroperitoneum. The retroperitoneum is deep in the abdomen (tummy) and pelvis, behind the abdominal lining, where organs such as the major blood vessels, kidneys, pancreas and bladder are located.

The main types of sarcoma that occur in the retroperitoneum are:

Signs and symptoms

Symptoms of retroperitoneal sarcomas can vary depending on the size and location of your tumour. They may include:

  • A noticeable lump in the abdomen 
  • Increase in abdominal girth
  • Dull pain in the abdomen or back
  • Intense abdominal pain with bleeding

Other rare symptoms include early satiety (meaning feeling full after eating a small amount of food), weight loss, hernia or anaemia. 

Types of diagnostic scans

A diagnosis of retroperitoneal sarcoma may start with a visit to your GP who will then refer you to a specialist doctor. Some retroperitoneal sarcomas are discovered through investigations for another medical condition or are diagnosed after surgery for a different problem. 

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

  • Physical examination – looking at and feeling any lump
  • A scan – taking pictures of the inside of the body using ultrasound, x-ray, CT or MRI
  • A biopsy – taking and testing a tissue sample. Core needle biopsies use a core (meaning hollow) needle to remove the tissue.

A clear diagnosis will be made after a pathologist with experience of sarcoma has examined a tissue sample. The biopsy can also help to tell the difference between a sarcoma and other conditions occurring in the abdomen. It can also help to decide the correct treatment for other retroperitoneal conditions.

Types of diagnostic scans and tests


A scan that uses sound waves to create images from within the body.


Uses x-radiation to take images of the dense tissues inside the body such as bones and tumours.


The Computer Tomography (CT) scan takes a number of x-rays to make a 3D image of an affected area.


Magnetic Resonance Imaging (MRI) uses magnets to create an image of the tissues of the body.

Blood test

Laboratory analysis of a blood sample.


Taking and testing a sample of tissue from the tumour.


Examination of a tissue sample by a pathologist under a microscope to identify disease.

Understanding the diagnosis

The diagnosis of a retroperitoneal sarcoma is mostly made from a needle biopsy and analysis of tissue by a pathologist in combination with the CT scan appearance. A diagnosis of
retroperitoneal sarcoma should be confirmed by a specialist sarcoma pathologist who will identify the type of sarcoma and grade of the tumour.

Identifying the stage and grade of a cancer means your doctor can advise on the best course of treatment for you. It also describes the cancer in a common language which is useful when your doctor is discussing your case with other doctors or healthcare professionals.

The stage of cancer is measured by how much it has grown or spread. This can be seen on the results of your scans or tests. The results from a biopsy can tell what grade the cancer is. 


  • Low-grade means the cancer cells are slow-growing, look quite similar to normal cells, are less aggressive, and are less likely to spread
  • Intermediate-grade means the cancer cells are growing slightly faster and look more abnormal
  • High-grade means cancer cells are fast growing, look very abnormal, are more aggressive and are more likely to spread


Most sarcomas are staged by looking at:

  • The size and grade of the tumour
  • Whether the tumour is deep in the body or superficial. This means closer to the surface.
  • Whether it has spread to another part of the body 

Most retroperitoneal sarcomas are more than 5cm in size and deep in the body. This makes the grade of the cancer a more important factor when finding out the stage of your cancer. 

  • Stage 1 means the cancer is low grade, small (less than 5cm) and has not spread to other parts of the body
  • Stage 2 means the cancer is of any grade, usually larger than stage one but has not spread to other parts of the body
  • Stage 3 means a high grade cancer that has not spread to other parts of the body
  • Stage 4 means a cancer of any grade or size that has spread to any other part of the body


In England and Wales, the National Institute for Health and Care Excellence (NICE) recommends that anyone with sarcoma should be referred to a specialist sarcoma team for daignosis and treatment.

People with a retroperitoneal sarcoma should be referred to a sarcoma centre with special expertise in managing this type of tumour. Treating retroperitoneal sarcomas has particular challenges, and experience of treating this tumour type will vary between sarcoma treatment centres. Outcomes for people with retroperitoneal sarcoma will be improved by concentrating their treatment at centres with staff who are experienced in managing this type of tumour.

In Northern Ireland, retroperitoneal sarcoma is diagnosed and treated across a number of hospitals in Belfast. People in Scotland should be referred to the Scottish Sarcoma Service
for treatment. Your case will be managed by a team of experts from a wide range of health care professions called a multidisciplinary team (MDT). Your MDT will include your sarcoma clinical nurse specialist, surgeon and other healthcare professionals involved in your care.

The European Society of Medical Oncology (ESMO) Guidelines for soft tissue sarcoma recommends that all patients with a suspected retroperitoneal sarcoma should be referred to a high-volume sarcoma centre for confirmation of diagnosis and treatment. This means a centre that sees a large number of retroperitoneal sarcoma patients a year. 

Types of treatment

The treatment for retroperitoneal sarcoma is highly individualised and depends on the size and location of your tumour. The main types of treatment are: 


Surgery is the main treatment for this type of sarcoma. The surgeon will remove the tumour and will aim to take out an area of normal tissue around it too when possible. This is known as taking a margin. Retroperitoneal sarcomas can sometimes touch or press on surrounding organs. In  these cases, the surgeon will aim to remove the tumour along with any organs next to it ‘en bloc’, meaning as a whole. 

Depending on the size and location of your tumour, the surgery you have may take away part of or whole organs such as the kidney, colon (bowel), pancreas, spleen or bladder which can have implications on your quality of life. Your surgeon will explain to you if this is required and the implications of removing the organ attached or next to your tumour. A small number of people will need a colostomy or urostomy following surgery. In cases where it is not possible to remove the tumours completely, surgery is unlikely to be recommended.

The treatment you receive should take into account your individual situation and your doctor or clinical nurse specialist should talk you through all possible treatment alternatives. You should also have the opportunity to ask any questions you may have regarding the future implications of your surgery. 

Surgery for retroperitoneal sarcoma can be complex and only a small number of surgeons in the UK are specialists in this type of surgery. Your surgeon should also be a core or extended member of your sarcoma MDT. The quality of surgery received is critical to a patient’s outcome so it is important that the surgeon operating on you has sufficient expertise in operating on sarcomas that occur in the retroperitoneum. Surgeons with this expertise include gastrointestinal surgeons. 

Rarely a colostomy is formed during surgery to divert a section of the large intestine (colon) through an opening in the abdomen (tummy). The opening is known as a stoma. A pouch
is placed over the stoma to collect waste products that would usually pass through the colon and out of the body through the anus (back passage).

If you have had your bladder removed you will need a urostomy. A urostomy is formed during surgery to allow drainage of urine through an opening in the abdomen (tummy). The opening is known as a stoma. A pouch is placed over the stoma to collect waste products that would usually pass through the bladder and urethra. The potential need for a colostomy or urostomy should be discussed with your surgeon.


This treatment uses high-energy radiation beams to destroy cancer cells. It is not routinely used to treat retroperitoneal sarcomas.

In some cases, radiotherapy to the tumour can be used before surgery to treat the tumour when it is close to vital structures, such as the organs in the retroperitoneum.  It can also be used after surgery to kill any local cancer cells. If the tumour is located near to an organ and there is a risk that the organ will be damaged by radiation, then this treatment will not be used.  


This treatment uses anti-cancer drugs to destroy cancer cells. Different sarcoma sub-types respond in different ways to chemotherapy. The use of chemotherapy as a treatment for retroperitoneal sarcomas is dependent on the types of cells that make up the tumour. In some sub-types it is used to try and shrink a large tumour so it is safe to be operated on. Sometimes the tumour completely disappears when treated by chemotherapy. In this case, radiotherapy is used to kill off any local cancer cells that remain in the area of the tumour. 

Chemotherapy is sometimes used after surgery to prevent the cancer coming back. Chemotherapy is also used to treat sarcomas that have spread to other parts of the body.

Discuss chemotherapy treatment with your specialist team who will be able to give you specific information about your sub-type.

Clinical trials

You may be offered an opportunity to take part in a study to investigate new diagnosis methods, drugs or treatments. Some studies also look at the care and well-being of patients. Your doctor or nurse can give you more information on opportunities for you to take part in a clinical trial.

After treatment

After treatment, you will have regular follow-up appointments for several years. You should receive a follow-up schedule from your sarcoma clinical nurse specialist. The usual practice will include:

  • A chance to discuss symptoms
  • A physical examination and CT, ultrasound or MRI to look for any signs of the sarcoma returning


Retroperitoneal sarcoma can reappear in the same area after treatment. This is called a local recurrence. 

Retroperitoneal sarcoma can come back near the site of your first tumour or spread through to the abdomen. If the sarcoma does reappear, it is important to get guidance on further management from the specialist sarcoma centre. Your further treatment will be assessed on an individual basis. 

It is useful to check for recurrences yourself through self-examination: your doctor or sarcoma clinical nurse specialist can tell you what to look for.

If you are worried about your sarcoma returning, contact your doctor or nurse. They may decide to bring forward the date of your follow up appointment to investigate your concerns.

You may experience side effects from your treatment. If you have had major abdominal surgery, it may affect how you eat. Specialist dieticians can give you advice and support on making changes to your diet.

What if my cancer spreads?

Sometimes sarcoma can spread to other parts of the body. This is called metastasis or secondary cancer. In retroperitoneal sarcoma patients, secondary cancer may appear in the lungs, which is why a chest x-ray is taken at follow-up appointments.

Treatment for secondary cancer may involve surgery, radiotherapy or chemotherapy as appropriate. Your treatment will be assessed on an individual basis.