A new metastatic breast cancer diagnosis is overwhelming, but focusing on what’s in front of you and what you might expect from living with the disease may help. Knowing about potential side effects of chemotherapy or hormonal therapy, such as back pain, can help you recognize and manage issues sooner to make it easier to cope.

Chemotherapy is a long-standing treatment option for metastatic breast cancer. As crucial as it is in increasing survival (and progression-free survival), chemotherapy can have a wide range of side effects and long-term complications. One possible side effect is sciatica, causing pain in your back, legs, feet, and other parts of your body. “After chemo, I really thought something was going on with my leg, as the bone pain in my shin just kept getting worse,” one MyBCTeam member wrote. “It turned out to be pressure on my sciatic nerve.”

The pain can be intense and persistent, lower your quality of life, and — if left untreated — lead to permanent nerve damage. Read on to learn more about sciatica from chemo, including what sciatica pain feels like and how it can be managed.

What Is Sciatica, and What Does It Feel Like?

Sciatica is pain that radiates along the sciatic nerve. The sciatic nerve starts in the lower back and extends down the hips and buttocks to the back of each leg. Sciatica is most often caused by a pinched or compressed sciatic nerve, which leads to inflammation and pain. The pain can range from mild to severe and is often described as a sharp, radiating pain in the hips and lower back that feels like burning or an electric shock. Compression on the nerve from improper back support while sleeping can lead to nighttime or morning back pain. Sometimes, sciatica can lead to tingling or numbness in the leg.

Many MyBCTeam members have shared their experiences with sciatica pain. Some say it’s relentless and unbearable, while others describe it as a dull ache, in comments like these:

• “I went in to have my fifth round of chemo. Fifteen minutes in, I felt a pain that started in my back and ran around to my side and down my leg. It was unbearable.”
• “The pain is from the foot up to my buttock, but the worst is the back of the thigh. I am taking tamoxifen but not sure that is it.”
• “I have been having sharp shooting pain in my left leg. It started as a gradual dull pain around my butt area then went all the way down my leg to my ankles. Can this be related to the chemo and anastrozole I’m taking?”
• “My sciatic pain started midway through my first six chemo treatments and has now progressed to the point where I can hardly function.”

Because sciatica affects people differently, it’s essential to tell your oncology team about any new or worsening symptoms — like low back pain that radiates down your leg — as soon as they occur.

Nerve Damage From Chemotherapy and Sciatica

Although chemotherapy can slow the progression of many types of cancers, it also can cause a variety of side effects, some of which can be severe. Some breast cancer treatments have been shown to affect the nervous system, potentially leading to nerve damage.

Chemotherapy-Induced Peripheral Neuropathy

Chemotherapy-induced peripheral neuropathy (CIPN) is a nerve-damaging complication of chemotherapy that causes numbness, tingling, and pain — often described as pins and needles — in the hands or feet. CIPN can lead to muscle weakness and balance problems that may place additional strain on the lower back and sciatic nerve.

CIPN can not only interfere with simple activities, such as picking up an object or buttoning a shirt but can also lead to serious complications, such as dangerous falls, breathing problems, and even paralysis.

Certain types of chemotherapy drugs are more likely to cause nerve damage. Medications widely used in breast cancer treatment that can cause nerve damage or changes include:

• Taxanes — Paclitaxel (Abraxane, previously also sold in the U.S. as Taxol) and docetaxel (Taxotere, Docefrez)
• Platinum-based drugs — Cisplatin (Platinol), carboplatin (Paraplatin), and oxaliplatin (Eloxatin)
• Vinca alkaloids — Vincristine (Oncovin, Vincrex) and vinorelbine (Navelbine)
• Hormone therapy drugs — Anastrozole (Arimidex), letrozole (Femara), exemestane (Aromasin), and tamoxifen (Soltamox)

The likelihood of developing CIPN depends on the type of chemotherapy drug, its dose, schedule, and whether it’s given with other chemotherapy drugs. Your previous treatments (surgery, radiation, and chemotherapy) and other health conditions also play roles. However, CIPN is one of the most serious complications associated with anticancer drugs.

CIPN occurs in 57 percent to 83 percent of people who’ve received taxanes. Of those people, 2 percent to 33 percent experience severe neuropathy. CIPN typically starts within the first two months of chemotherapy and can last months to years.

Taxane Acute Pain Syndrome

In many cases, CIPN develops from acute (early-onset) pain, usually in the hips, legs, and feet. Taxane chemotherapy drugs often cause this type of pain, called taxane acute pain syndrome (TAPS), which is also known as paclitaxel-associated acute pain syndrome or taxane-induced myalgia-arthralgia syndrome. Compared with CIPN, TAPS pain is described as sharper and more burning or radiating, and it usually goes away in a few days.

TAPS occurs in about 70 percent of people undergoing taxane chemotherapy. The symptoms generally start within 24 to 48 hours of receiving taxane and can last up to a week. The syndrome is believed to be caused by toxic effects of the drug and inflammation. Researchers believe that TAPS nerve pain gradually develops into CIPN.

Aromatase Inhibitor-Induced Musculoskeletal Symptoms

Aromatase inhibitors, such as letrozole, anastrozole, and exemestane, are effective at lowering the risk of breast cancer after menopause. These hormonal therapies are sometimes combined with cyclin-dependent kinase 4/6 inhibitors such as abemaciclib (Verzenio), palbociclib (Ibrance), and ribociclib (Kisqali).

Aromatase inhibitor medications can cause joint pain that affects the hands, knees, back, hips, and shoulders in what is called aromatase inhibitor-induced musculoskeletal symptoms (AIMSS). AIMSS also can cause stiff joints and sore, weak muscles. Aromatase inhibitors work by lowering the body’s estrogen levels, which has been shown to reduce bone density and increase the risks of arthritis and osteoporosis. Although the pain caused by aromatase inhibitors is more of a stiffness than the sharp pain of neuropathy, muscle weakness and inflammation caused by these drugs can affect the lower back and sciatic nerve. As a result, symptoms that resemble sciatica can develop.

One small study found that about 48 percent of participants with breast cancer who were on hormone therapy experienced muscle and joint pain. In a study published in the journal Current Oncology, researchers reported that about 20 percent of people using an aromatase inhibitor stopped the treatment because of the severity of their joint pain. AIMSS generally appears about two months after treatment begins and peaks about four months later. In some cases, AIMSS occurs up to two years after starting the treatment.

Back Pain From Spinal Metastases

Breast cancer that has spread to the spine can also cause back pain. Metastatic breast cancer, by definition, is breast cancer that metastasizes (spreads) to another part of the body, commonly the lungs, bones, liver, or brain. Breast cancer that spreads to the bone (bone metastases) often affects the spine. When this happens, it’s known as spinal metastases.

Studies have shown that about two-thirds of bone metastases are spinal metastases, and one-third of spinal metastases cause symptoms, including:

• Pain
• Neurological issues
• Balance issues

Pain occurs most often, affecting approximately 90 percent of people with spinal metastases from metastatic breast cancer. These symptoms can be debilitating and greatly impact quality of life.

The type of spinal or back pain can give doctors clues to the tumor’s location and severity. For example, shooting pain or a burning sensation may indicate that the tumor is pressing against or irritating certain nerves. Constant, deep, aching back pain that’s worse at night may indicate tumor growth or tumor-induced inflammation.

Talk to your oncologist if you’re experiencing back pain with or without chemotherapy so that they can help you pinpoint its cause and recommend a pain management plan.

How To Manage Sciatica and Lower Back Pain

Lower back and sciatica pain caused by chemotherapy and hormone therapy drugs can greatly diminish quality of life during breast cancer treatment. Sometimes these drugs need to be used long term, making strategies to manage the painful side effects even more important.

To relieve pain and symptoms of nerve damage, your doctor may recommend drugs such as:

• Pain relievers, including nonsteroidal anti-inflammatory drugs (NSAIDs)
• Anti-seizure medications, such as gabapentin or pregabalin
• Antidepressants, such as duloxetine
• Corticosteroids and antihistamines, which may be used short term to control inflammation
• Pain-relieving patches or cream, such as lidocaine or capsaicin

Your doctor might reduce the dose of your chemotherapy or hormone therapy or recommend trying a different drug.

Nondrug ways to manage pain include physical therapy and exercise to help improve mobility, balance, and coordination, as well as practices like acupuncture and massage. Some researchers suggest that cancer rehabilitation should start with prehabilitation — getting ready for treatment before you start it. The goal of prehabilitation is to boost physical and mental health as much as possible before chemotherapy, radiation, or surgery lowers them.

For some people, it might also be helpful to stop smoking or lose weight.

Talk to Your Doctor About Nerve Pain Caused by Chemotherapy

If you develop nerve pain during or after receiving chemotherapy, it’s important to talk to your doctor right away to prevent serious complications and permanent nerve damage. It’s also important to rule out the possibility that your pain is caused by another serious medical condition, such as:

• Diabetes
• An inflammatory or autoimmune disease
• A brain or spinal cord disorder
• Blood vessel problems
• Vitamin deficiency

Your doctor may refer you to a pain specialist, who can guide you through strategies to treat and manage back pain and sciatica pain caused by breast cancer chemotherapy or newer treatments for metastatic breast cancer.

Talk With Others Who Understand

MyBCTeam is the social network for people with breast cancer and their loved ones. On MyBCTeam, more than 68,000 members come together to ask questions, give advice, and share their stories with others who understand life with breast cancer.

Are you experiencing lower back pain and sciatica pain after chemotherapy? What strategies have you used to help manage the pain? Share your experiences in the comments below, or start a conversation by posting on your Activities page.