Spindle Cell Sarcoma

What is spindle cell sarcoma?

Spindle cell sarcoma is a rare form of bone cancer or soft tissue cancer. Sarcomas are clumps of abnormal cells (tumors) that form in bone and connective tissue. With spindle cell sarcoma, these cells look like spindles — long and narrow with ends that taper like a candlestick — when viewed with a microscope.

Thanks to modern lab tests, healthcare providers can identify over 75 kinds of sarcoma subtypes. One of these is a spindle cell sarcoma. “Spindle cell sarcoma” is a broad and encompassing term for sarcoma that can’t be classified by specific lab tests, including stains and tests that look for genetic characteristics.

Spindle cell sarcomas most often form in long bones, including your:

• Thigh bone (femur).
• Shin bone (tibia).
• Upper arm bone (humerus).

But people have had spindle cell sarcomas in their pelvis, in regions of their head and neck, and elsewhere.

Types of spindle cell sarcoma

All sarcomas start in soft tissue, including fat, muscle, blood vessels, nerves and tissue surrounding bones. Healthcare providers further classify spindle cell sarcoma based on what type of cells the cancer develops in.

Understanding cell type and characteristics allows healthcare providers to better understand how likely it is that the cancer will spread. It can also help them identify the best treatments.

While “spindle cell sarcoma” is a broad term, some of the main types of spindle cell sarcoma include:

• Undifferentiated pleomorphic sarcoma: Just like the name says, the cells are undifferentiated, meaning it’s unclear in what type of cell the cancer started. The diseased cells in the tumor are “pleomorphic” — coming in all shapes and sizes.
• Fibrosarcoma: Fibrosarcomas develop in cells called fibroblasts. Fibroblasts are key building blocks of connective tissue.
• Leiomyosarcoma: These start in smooth muscle cells. They’re different from those cells in skeletal muscle tissue, which we use for movement and strength. Instead, smooth muscle cells make up soft tissue inside organs, body cavities and some bones.

How common is this condition?

Like sarcomas in general, spindle cell sarcomas are rare. They make up less than 10% of bone and soft tissue cancers. It’s so rare that your healthcare provider may not suspect this type of cancer at first. It may take several appointments, specialists and tests before you receive a diagnosis.

Anyone can get spindle cell sarcoma, but it’s most common in people over 40 years old. People diagnosed with undifferentiated pleomorphic sarcomas are usually between 60 and 70 years old.

What are the symptoms?

Spindle cell sarcoma symptoms vary depending on tumor size, the number of tumors and which bones (or other body parts) contain cancer cells. Signs to look out for include:

• Bone pain that may be constant or that comes and goes.
• A broken bone in the place where cancer has weakened the bone (this is called a pathological fracture).
• Tenderness or swelling at the tumor site.
• Trouble moving a joint that’s near the tumor.
• Fatigue (extreme tiredness that doesn’t improve with sleep or attempts to recharge).
• Malaise (feeling generally unwell without having a reason why).

What causes spindle cell sarcoma?

Like all cancer, spindle cell sarcoma starts when otherwise healthy cells become malignant. Malignant cells grow out of control and form tumors that can damage nearby healthy tissue. The cancer cells can break off from the original tumor and spread, damaging tissues and organs throughout your body. This is called metastasis, or metastatic cancer.

The presence of spindle cells (when they grow appropriately) is usually a good thing. Spindle cells form in places where there’s tissue damage. Spindle cells are a sign that you’re healing. They go away once the injury heals.

With spindle cell sarcoma, the spindle cells continue growing and multiplying. Scientists haven’t identified a single factor that causes the cells to turn malignant.

Researchers have discovered genetic mutations that may make a person more likely to develop this cancer. A mutation is an error in your genes, the instructions that tell your cells how to work. With spindle cell sarcoma, these mutations are likely inherited, which means they run in families.

Risk factors

Several factors may increase your risk of developing spindle cell sarcoma, including:

• Bone infarction: With a bone infarction, bone tissue dies because it’s not getting enough blood. Blood contains the oxygen bone tissue needs to live.
• Fibrous dysplasia: With this condition, fibrous bone-like tissue replaces healthy bone tissue. Fibrous dysplasia increases your risk of fractures and (in rare cases) fibrosarcomas.
• Osteomyelitis: Osteomyelitis is an infection that affects the spongy tissue (marrow) inside some bones. It can happen if bacteria or another germ travels from your bloodstream to your bone and infects the cells there.
• Paget’s disease of the bone: This is a long-lasting (chronic) condition that causes weak bones that break easily. It can increase your risk of developing bone cancers, including spindle cell sarcoma.
• Previous radiation therapy for cancer: Radiation treatment directs energy (usually high-powered X-rays) toward tumors to kill cancer cells. In rare cases, spindle cell sarcomas have formed in sites treated with radiation. When this happens, the sarcoma usually forms several years (seven to 20) following treatment. Radiation-associated cancers occur in far less than 1% of all people who receive radiation therapy treatment.

What are the complications of spindle cell sarcoma?

This cancer can make you more prone to fractures (bone breaks) at the tumor site. When a bone breaks, cancer cells from the tumor can travel to places near the tumor.

It’s controversial as to whether this type of bone break changes the overall cancer prognosis (or likely outcome) or whether outcomes relate specifically to metastatic (distant) spread of the cancer.

How is spindle cell sarcoma diagnosed?

You’ll likely need many procedures and tests before your healthcare provider can diagnose and stage your cancer. Cancer staging allows providers to classify cancer’s severity based on the size and location of the tumor and whether the cancer has spread. Cancer staging for bone cancers considers whether a tumor is high-grade or low-grade. Higher-grade tumors have more abnormal-looking cells. They’re more likely to grow and spread quickly.

Many spindle cell sarcomas are high-grade.

Imaging

Imaging can’t show cancer type, but it can show tumor size and location. It can also show if the cancer has spread from the tumor where it first started (the primary tumor).

• X-rays can show tumors or other abnormalities in your bones. Chest X-rays can show if cancer has spread to your lungs. Metastatic spindle cell sarcoma often spreads to your lungs first.
• An MRI uses a large magnet, radio waves and a computer to take pictures of structures inside your body. Unlike X-rays, an MRI can show soft tissue in fine detail. It’s especially useful in helping providers diagnose soft tissue masses that may be concerning for a sarcoma.
• CT scans use X-rays and a computer to take 3D images of bone and soft tissue. With spindle cell sarcoma, CT scans can show if the cancer has spread to soft tissue, and are best for detecting potential fractures or areas of bone weakening.
• PET scans use a tracer to locate cancer cells throughout your body. They can detect metastasized spindle cell sarcoma. You may also need PET scans to monitor how your treatment is working. PET scans aren’t used for all types of sarcomas. Your healthcare provider will know if a PET scan is appropriate.

Blood tests

There isn’t a specific blood test that can detect spindle cell sarcoma. Still, blood tests provide important information about your health that your provider needs to know. In general, blood tests provide information about your:

• Blood cells.
• Organ function.
• Enzyme levels (enzymes are chemicals that allow organs to carry out important processes).

Biopsy

A biopsy is the best way to know for sure if a tumor is cancerous. It’s also the only way to know the type of cancer and its grade. During a biopsy, a healthcare provider removes a tissue sample from the tumor and sends it to a lab to test the cells.

Most people with spindle cell sarcoma receive a needle biopsy. Healthcare providers numb the tissue surrounding the tumor and then use a small, hollow needle to remove the sample. You may need an X-ray or CT scan to guide the biopsy so your provider can see the exact spot in your body where they should direct the needle.

How is spindle cell sarcoma treated?

Your treatment depends on your health, where the tumors are, their size, their grade and other factors. Treatment also depends on whether you’re receiving treatment for the first time or if the cancer has returned following treatment (recurrent).

Surgery

Surgery aims to remove the tumor while preserving as much of your bone as possible. Removing all signs of cancer in the primary tumor and any secondary tumors can cure the cancer. Still, cancer is much more challenging to eliminate completely once it spreads beyond the primary tumor.

Chemotherapy

Chemotherapy uses drugs to kill cancer cells throughout your body. You may need chemo before surgery to shrink a tumor so it’s easier to remove. Or you may need chemo after surgery to kill any remaining cancer cells. Chemotherapy is also a form of palliative care. Even if the cancer isn’t curable, chemo can still destroy cancer cells to help relieve symptoms like bone pain.

Most people receive a combination of chemotherapy drugs to make treatment more effective. You may need different chemo drugs based on whether you’re receiving treatment for the first time, not seeing a great response to certain chemo drugs or if the cancer has returned after remission. Remission is when cancer improves or disappears following treatment.

Radiation therapy

External beam radiation therapy (EBRT) uses a machine that directs X-rays toward the tumor, killing cancer cells. You may need radiation to destroy the tumor if you’re not a candidate for surgery. Sometimes, a surgeon can’t access the tumor with surgery. It may be deeply embedded in tissue or too close to vital structures to remove safely. In that case, you may need radiation instead.

Like chemotherapy, radiation therapy can relieve symptoms if the cancer isn’t curable.

What are the complications or side effects of treatment?

Chemotherapy and radiation side effects are common during cancer treatment and can continue after treatment, too. Ask your healthcare provider about potential side effects based on the treatments you’ll receive.

Is spindle cell sarcoma curable?

Providers can cure spindle cell sarcomas by removing all signs of cancer. It’s much easier to cure spindle cell sarcoma that hasn’t spread beyond the primary site. It’s much more challenging to treat sarcomas that have spread. Metastatic spindle cell sarcomas are rarely curable.

How serious is spindle cell sarcoma?

This type of cancer is often high-grade, which means it grows and spreads quickly. It often returns following remission, sometimes in the primary tumor site and sometimes in a different place.

Still, every cancer diagnosis is unique. Your healthcare provider can tell you the likely treatment outcomes (prognosis) based on the specific type of cancer, the stage, your overall health, treatment response and various other factors. Your healthcare provider is your best resource for advising you on what this diagnosis means for you.

When should I see my healthcare provider?

Your healthcare provider will tell you how often you’ll need treatments or visits to check if the cancer’s still in remission. Most people in remission need frequent appointments in the beginning. The longer you’re cancer-free, the less often you’ll need follow-up appointments to ensure it hasn’t returned.

What follow-up treatments will I need?

You may need additional procedures depending on how much bone the surgeon had to remove. These procedures can help you maintain function in that bone. For example, you may need a bone graft. A bone graft uses tissue from another part of your body or from a donor to replace the removed tissue. You may need an artificial limb. You may need additional treatments to adjust to these changes.

What questions should I ask my healthcare provider about spindle cell sarcoma?

Questions to ask include:

• Where is the cancer located?
• What stage/grade is the cancer?
• What does the stage/grade mean for my treatment plan?
• What treatment side effects should I expect?
• Is my cancer curable?
• What are the goals of treatment?
• Can you connect me to palliative care resources to help me navigate my cancer diagnosis?

A note from Cleveland Clinic

Spindle cell sarcoma is a stressful diagnosis to receive. The condition itself can make you feel tired and uncomfortable. Treatments are often intensive and may involve challenges like adjusting to a graft or an artificial limb. It’s important to have honest, direct conversations with your healthcare provider in the beginning so you understand your diagnosis, including how treatable your cancer is. Ask about treatment goals and what lifestyle adjustments you may need to make during treatment and recovery. Spindle cell sarcoma is an aggressive cancer, but there are treatments that can slow its growth and, in some cases, cure it completely. Discuss what to expect with your provider.