Small Intestine Leiomyosarcoma

Small intestine leiomyosarcoma is a rare and aggressive cancer that develops in the smooth muscle cells of the small bowel. Early diagnosis is challenging because the tumor grows slowly and may not cause symptoms until it reaches an advanced stage, making surgical removal the cornerstone of treatment.

Table of contents

• What is Small Intestine Leiomyosarcoma?
• Where Does It Occur?
• How Common Is This Cancer?
• Signs and Symptoms
• How Is It Diagnosed?
• Treatment Options
• Prognosis and Survival

What is Small Intestine Leiomyosarcoma?

Small intestine leiomyosarcoma is a type of cancer that originates from smooth muscle cells. These muscle cells are found within layers of the small bowel called the muscularis mucosa (the thin layer of muscle beneath the lining) or the muscularis propria (the thicker outer muscle layer)^[1]. This cancer belongs to a larger group of cancers called soft tissue sarcomas, which are malignant tumors that develop in the body’s soft tissues^[2].

Leiomyosarcoma (often abbreviated as LMS) is known for being aggressive and fast-growing. The cancer cells can travel through the bloodstream and spread to other soft tissues in the body^[2]. What makes this cancer particularly challenging is that it can double in size in as little as one month^[2].

Before the year 2000, small intestine leiomyosarcoma was often confused with another type of tumor called gastrointestinal stromal tumors (GISTs). These two cancers look similar under the microscope, but they are actually different diseases with different treatments and outcomes^[1][12]. Today, doctors can tell them apart using special tests that look at markers inside the cells.

Where Does It Occur?

• Jejunum
• Ileum
• Duodenum

The small intestine, also called the small bowel, is a long tube-like organ that connects the stomach to the large intestine. It is responsible for absorbing nutrients, vitamins, minerals, and water from the food we eat^[18]. The small intestine has three parts: the duodenum (closest to the stomach), the jejunum (the middle section), and the ileum (which connects to the large intestine).

Leiomyosarcoma can develop in any part of the small intestine, but it is most commonly found in the jejunum, ileum, and duodenum^[1][3]. Most of these tumors occur in the part of the small intestine that is near the large intestine^[6][9].

How Common Is This Cancer?

Small intestine leiomyosarcoma is extremely rare. Malignant tumors of the small bowel are uncommon to begin with, representing less than 2% of all tumors in the digestive system^[3][10]. Leiomyosarcoma is just one type of small bowel cancer, making it even rarer.

To put this in perspective, about 15,000 people in the United States are diagnosed with soft tissue sarcomas each year. Of those, leiomyosarcoma accounts for only 10% to 20%^[2]. When leiomyosarcoma occurs specifically in the small intestine, it represents about 2% of all gastrointestinal tumors^[3].

This cancer tends to affect people in their 60s, and studies have shown that the peak incidence is in males in their 60s^[3]. However, in terms of overall leiomyosarcoma (in all body locations), it is most common in females over age 50^[2].

Signs and Symptoms

Many people with small intestine leiomyosarcoma do not develop symptoms until the disease has reached an advanced stage. This delay in symptoms is one reason why the cancer is often discovered late^[1][2]. When symptoms do appear, they can be vague and may be mistaken for other, less serious conditions.

The most common symptom is abdominal pain, which occurred in 85% of patients in one study^[4]. Other symptoms may include:

• Chronic or recurring abdominal pain or cramps, particularly in the middle of the abdomen^[1][6]
• Unexplained weight loss^[2][6]
• Blood in the stool, which may appear as black stools^[2][4]
• A lump or mass that can be felt in the abdomen^[2][4]
• Nausea and vomiting^[2]
• Loss of appetite^[2]
• Anemia (low red blood cell count)^[4]
• Abdominal bloating^[2]
• Fever^[2]
• Fatigue or tiredness^[2]

In some cases, the tumor can cause serious complications like intestinal perforation (a hole in the bowel) or bowel obstruction (blockage). One study found that 30% of patients experienced intestinal perforation^[4].

If you experience any of these symptoms, especially abdominal pain that won’t go away or blood in your stool, you should see a doctor. While these symptoms can be caused by many conditions besides cancer, it’s important to have them checked out.

How Is It Diagnosed?

Diagnosing small intestine leiomyosarcoma is challenging because the symptoms are not specific and standard tests like upper endoscopy and colonoscopy often do not reveal abnormalities^[1]. In fact, in a study of 20 patients, the correct diagnosis of small bowel tumor was made before surgery in only one case^[4].

When small intestine leiomyosarcoma is suspected, doctors use several approaches to confirm the diagnosis:

Physical examination and medical history: A healthcare provider will examine you and ask about your symptoms and medical history, including any past illnesses or conditions^[2].

Imaging tests: Several types of scans can help see inside the body and locate the tumor. These include:

• Computed tomography (CT) scans – These are often the first test used. A CT scan of the chest and abdomen can reveal a mass in the small intestine and show if the cancer has spread to other areas like the lungs^[1][2].
• Magnetic resonance imaging (MRI) – An MRI can provide detailed images of soft tissues^[2].
• CT colonography and magnetic resonance enterography (MRE) – These specialized imaging techniques are particularly good for examining the small bowel^[1].
• Ultrasound – This may be used in some cases.

Biopsy: The most definitive way to diagnose leiomyosarcoma is through a biopsy, where a small sample of tissue is removed and examined under a microscope^[2].

Immunohistochemistry (IHC): This is a special laboratory test that is essential for confirming the diagnosis and distinguishing leiomyosarcoma from other similar-looking tumors, particularly GISTs. IHC looks for specific markers in the tumor cells^[1][7].

Because small intestine leiomyosarcoma looks very similar to GISTs under the microscope, immunohistochemistry is crucial for making the correct diagnosis^[1].

Treatment Options

Surgery is the only treatment that can potentially cure small intestine leiomyosarcoma. The main goal is to remove the entire tumor along with clear margins (cancer-free tissue around the edges)^[1][3].

Surgical resection: The standard surgical approach involves removing the part of the small intestine containing the tumor along with the adjacent tissue. This is called a wide small bowel resection with adjacent mesentery (the tissue that attaches the intestine to the abdominal wall)^[4]. The surgeon will perform an enlarged resection to ensure that all cancer cells are removed, and then reconnect the healthy parts of the intestine^[1].

In some cases, especially when the cancer has spread or returned, surgeons may need to remove multiple organs or perform extensive surgery to obtain cancer-free margins^[3]. This is sometimes called multivisceral resection.

Chemotherapy and radiation therapy: The role of chemotherapy and radiation therapy in treating small intestine leiomyosarcoma remains uncertain. Research has shown that neither chemotherapy nor radiotherapy significantly influenced survival or prognosis in patients with this cancer^[3][12]. These treatments have not been found to be consistently effective in slowing or stopping the progression of small bowel leiomyosarcomas.

However, chemotherapy may be used in some situations, particularly when the cancer has spread to other parts of the body or when the tumor is large^[9]. Some patients may be offered participation in clinical trials testing new treatment approaches.

Because this cancer is so rare, there are currently no standard guidelines specifically for small intestine leiomyosarcoma treatment. Each case should be discussed in a multidisciplinary setting with a team of specialists^[3].

Prognosis and Survival

The prognosis for small intestine leiomyosarcoma is generally poor, mainly because the cancer is often discovered at an advanced stage^[1][7]. However, outcomes are much better when the cancer is detected and treated early, particularly when complete surgical removal is possible^[2].

Several factors affect survival and prognosis:

Surgery makes a major difference: In one study, the 5-year cancer-specific survival rate was 66.5% for patients who underwent surgery, compared to 0% for those who did not have surgery^[12]. Another study found that about half of patients who had surgery survived five years^[4].

Complete tumor removal is critical: When surgeons are able to remove the entire tumor with clear margins (called R0 resection), patients have a much better chance of long-term survival^[3].

Cancer tends to return: Leiomyosarcoma has a high rate of recurrence (coming back after treatment). Studies suggest that the cancer returns nearly 40% of the time, with the highest risk in the first five years after treatment^[3][16].

How cancer spreads: Small intestine leiomyosarcoma typically spreads through several routes. It can spread through the bloodstream to distant organs, implant itself on the lining of the abdominal cavity, or invade nearby tissues directly. Spread through the lymph nodes is uncommon^[4]. In fact, only 7.9% of cases were diagnosed with lymph node spread^[12].

Research has identified several factors that affect survival. A large study found that being female was a protective factor, meaning women tended to have better outcomes. Risk factors that predicted worse outcomes included older age (65-79 years and 80 years or older), poor tumor differentiation (how abnormal the cancer cells look), more advanced tumor stage (T2 or higher), distant spread of the disease, and not having surgery^[12].

In one case series of four patients, the average overall survival was 33 months, ranging from 8 to 84 months^[3].

Despite these challenges, some patients do achieve long-term survival, especially when the cancer is caught early and completely removed through surgery.