Leiomyosarcoma is a rare soft tissue malignant tumor derived from the smooth/involuntary muscles.
In the human body three types of muscles are distinguished: the smooth or involuntary muscles, the heart muscle and skeletal or voluntary muscles. Smooth muscles contract without person’s control and are found in the walls of internal organs. The malignant tumors, which originate from this tissue are called leiomyosarcomas, whereas the tumors derived from the skeletal muscles are known as rhabdomyosarcomas. Since the smooth muscles are found almost everywhere in the body the tumor may arise in all the body parts, commonly the uterus, stomach, intestines and the retroperitoneum are affected. The tumor may originate from the smooth muscles of the blood vessels lining or from the muscular layer of the internal organs itself.
Leiomyosarcomas comprise 8-20% of all soft tissue sarcomas and are the most common type of uterine sarcomas. Mean age of the diagnosis is 54 years (49-60 years), it is seen in persons under 20 extremely rare.
Causes and risk factors
Some researchers suggest that there may be a genetic basis for leiomyosarcoma. Some inherited or sporadic mutations can contribute to the development of the tumor. In some persons leiomyosarcomas appear long after they have undergone the radiation therapy due to another type of malignancy.
Exposure to some chemicals (dioxins, weed killers, vinyl chloride) is known to increase the risk of developing leiomyosarcoma.
- Uterine leiomyosarcoma;
- Cutaneous leiomyosarcoma (originate from the pilo-erector muscles on the skin, which contract to make the hair of the skin to stand on end causing so-called goose bumps);
- Gastrointestinal leiomyosarcoma;
Symptoms may vary according to the location, size and dissemination of the tumor. When the tumor is relatively small it may be totally asymptomatic. As the tumor grows, it may cause pain and swelling. If the tumor arises in the uterus, abnormal vaginal bleeding, pelvic pain and discharge from the vagina may occur.
General cancer symptoms are common for leiomyosarcoma and include bloating in the abdomen, fatigue, fever, nausea, vomiting, weight loss. The tumor of the gastrointestinal tract may cause stomachache, black-colored stools (tarry, foul-smelling stools called melena due to gastrointestinal bleeding) and vomiting with blood. A change in bladder or bowel habits may also occur.
Leiomyosarcomas are highly aggressive tumors that tend to metastasize, especially to the lungs.
- Stage 1 – low grade cancer (slow-growing tumor made of the cells, which look almost like normal ones), the tumor is relatively small (less than 5cm) and has not spread throughout the body yet;
- Stage 2 – the disease of any grade, but larger than 5 cm that hasn’t disseminated;
- Stage 3 – a high grade tumor (the tumor grows fast and is made of non-differentiated highly abnormal cells) that hasn’t spread;
- Stage 4 – a cancer of any grade or size that has disseminated to any part of the body;
The diagnosis is made based on the following examinations:
- X-ray to assess the skeletal metastases;
- Ultrasound to verify the presence of the tumor within the body;
- CT/MRI to examine the suspicious site and find the metastases, identify the stage of the disease;
- EUS (Endoscopic Ultrasound Scan) is performed to investigate the tumors of the gastrointestinal tract;
- Angiography to see the location of the tumor in relation to the blood vessels, especially the major ones;
- Biopsy to verify the diagnosis and assess the prognosis;
Related: Alveolar rhabdomyosarcoma
Leoimyosarcoma is a resistant tumor and does not respond to chemo- or radiotherapy.
The common treatment of leiomyosarcoma is surgery, when the tumor is totally resected (the removal of the neoplasm with the nearby tissues) with a following biopsy. In general leiomyosarcoma is highly resistant to chemotherapy and radiation therapy. Howeverm the combination of surgery, chemo- and radiotherapy is usually used.
Chemotherapeutical agents used to treat leiomyosarcoma usually include:
Targeted drug therapy with pazopanib is used as an additional treatment to radiation therapy and chemotherapy.
The 5-year survival rate is 40% if the tumor originates from the uterus.