Leiomyosarcoma: symptoms, causes, diagnosis and treatment

Sarcoma UK says symptoms depend on the size and location of the tumour, and that you may have all, some or none of them before diagnosis. For soft tissue leiomyosarcoma the typical sign is a lump or swelling under the skin, often on an arm, leg or the trunk, that is increasing in size, larger than 5cm and usually painful, but not always.

The NHS describes the most common symptom of soft tissue sarcoma generally as a lump somewhere on the body, usually deep under the skin, solid to the touch, painless and hard to move around, which continues to grow and can become painful. Other symptoms depend on location, for example tummy pain and constipation near the tummy or a persistent cough near the lungs.

Cancer Research UK says a lump is more likely to be a sarcoma if it is big (for example more than 5 cm across) or getting bigger, is deep in the body tissues, is painful, occurs when you are older, has come back after surgery, or is in an area that has had radiotherapy.

• A lump or swelling that is growing, deep, or more than 5cm.

• Vaginal bleeding after menopause, between periods or that feels unusual (uterine type).

• Pain around the pelvis or stomach.

• Tummy pain or constipation if the tumour is in the abdomen.

The NHS says soft tissue sarcomas are rare cancers that start in soft tissue such as muscle and fat. Leiomyosarcoma arises from smooth muscle cells, sometimes called involuntary muscle because they cause organs to contract without our control. Sarcoma UK says it mostly affects adults and is very rare under 20.

There are two main types. Uterine leiomyosarcoma starts in the womb. Soft tissue (non-uterine) leiomyosarcoma starts in the soft tissues of the limbs, the tummy or the retroperitoneum. Cancer Research UK also lists large blood vessels and skin as possible sites, and describes a rarer inflammatory leiomyosarcoma.

Sarcoma UK says soft tissue leiomyosarcomas are usually found when a patient notices a lump on the leg, arm or trunk, although they may be found during investigation of other symptoms or a routine operation. A specialist doctor will diagnose through a series of tests: a physical examination, a scan (ultrasound, X-ray, CT, EUS, PET or MRI) and a biopsy.

For suspected uterine leiomyosarcoma, you may have a hysteroscopy (a procedure to look inside the uterus), a pelvic ultrasound and an endometrial biopsy. Sarcoma UK says uterine leiomyosarcoma can often be misdiagnosed as benign fibroids, and that fibroids that continue to grow after the menopause need further examination.

The NHS says the GP will examine any lump and may arrange blood tests and an ultrasound scan, then refer you for more tests or to a hospital specialist if needed. This may be an urgent referral and does not definitely mean cancer.

Sarcoma UK says surgery is the most common treatment, regardless of subtype and especially if the cancer has not spread. For uterine leiomyosarcoma limited to the uterus a hysterectomy is often recommended. The NHS says that for sarcomas in an arm or leg the surgeon tries to remove the cancer without removing the limb (limb sparing surgery), with amputation only rarely recommended, usually if the sarcoma returns.

Radiotherapy may be offered if the leiomyosarcoma is in a limb or the trunk, before or after surgery to reduce the risk of recurrence, or if surgery is not possible. Sarcoma UK notes studies suggesting radiotherapy may add no benefit to surgery for retroperitoneal tumours, and is not effective after surgery in uterine leiomyosarcoma, though it may help symptoms in inoperable tumours.

Sarcoma UK says there is limited data on chemotherapy for leiomyosarcoma that has not spread, and that there is potentially a role if the cancer has spread, if surgery is not possible or the tumour cannot be completely removed. The NHS says targeted medicines are sometimes used to slow the growth of certain soft tissue sarcomas.

The NHS says soft tissue sarcoma is rare and it is not always known what causes it. You might be more likely to get one if you are over 65, have had radiotherapy in the past, have untreated HIV (which can cause a type called Kaposi sarcoma), have neurofibromatosis or have had retinoblastoma.

Cancer Research UK says that for most soft tissue sarcomas the cause is unknown, and having a risk factor does not mean you will develop cancer.

Sarcoma UK says that after treatment you will have regular follow-up appointments for several years, with a schedule from your sarcoma clinical nurse specialist. Usual practice includes discussing symptoms, an examination, an MRI or ultrasound if required, and a chest X-ray to rule out secondary cancers in the lungs.

Leiomyosarcoma can reappear in the same area (local recurrence). Sarcoma UK says if it does, it is important to be treated as quickly as possible, possibly with further surgery or radiotherapy, and that new symptoms should be reported to your clinical team, which may bring the next appointment forward. The NHS says you do not need to wait for your next check-up if you are worried.

If the cancer cannot be cured, the NHS says the aim is to slow its growth and spread, help with symptoms and help you live longer, supported by a palliative care or symptom control team.

See a GP about any unexplained lump or swelling, particularly one that is growing, deep, painful or larger than about 5cm, and about vaginal bleeding after the menopause or that is unusual for you. Lumps are very common and most are not cancer, but the NHS says it is important to get them checked, because if symptoms are caused by cancer finding it early may make it easier to treat.

Sarcomas are rare and are treated by specialist sarcoma teams. On the NHS the route is GP, then a suspected cancer referral, with diagnosis and treatment planning through a multidisciplinary sarcoma team; your clinical nurse specialist is the main contact.

Private consultations can provide earlier imaging or a second opinion, but treatment decisions for a rare cancer are best made by a specialist sarcoma multidisciplinary team in either sector, so ask which team will manage your care.