Shoulder pain is a common and often complex complaint among breast cancer patients and survivors. This discomfort can range from mild stiffness to severe, limiting pain that impacts daily life. Up to 68% of individuals treated for breast cancer experience some degree of shoulder or arm restriction. The causes are varied, stemming from the cancer itself or, more frequently, from the aggressive treatments used to eradicate the disease. Understanding the source of the pain is the first step toward effective management and proper medical evaluation.
Shoulder Pain as a Sign of Advanced Disease
The most concerning, though less common, cause of shoulder pain is the potential spread of the cancer. Breast cancer frequently metastasizes to the bone, targeting the skeletal structures of the shoulder girdle, including the humerus, scapula, and spine. When cancer cells form lesions, they weaken the structure—a process called osteolysis—and cause a deep, persistent ache.
This metastatic pain often presents as a constant, dull, or gnawing sensation not relieved by rest or standard anti-inflammatory medications. The pain may be noticeable at night or worsen with arm movement, sometimes mimicking orthopedic issues. Pain in the right shoulder blade area can also be referred pain from metastasis to the liver.
Treatment-Related Causes of Post-Surgical Pain and Restriction
Most shoulder issues are a direct consequence of the necessary cancer treatments. Surgical procedures, particularly those involving the lymph nodes, can cause trauma to surrounding muscles and nerves. A full axillary lymph node dissection (ALND) carries a higher risk of complications than a sentinel lymph node biopsy (SLNB) because it is more extensive.
The trauma can lead to scar tissue and muscle tightness across the chest wall and armpit, restricting natural shoulder movement and causing chronic stiffness. Furthermore, the intercostobrachial nerve, which supplies sensation to the underarm and upper inner arm, is often damaged during axillary surgery. This nerve injury can result in numbness, tingling, shooting pain, or a burning sensation, known as dysesthesia.
Lymphedema, the buildup of lymphatic fluid, is another significant contributor. When lymph nodes are removed or damaged, the arm’s natural drainage system is compromised, leading to swelling in the arm and shoulder. This increased fluid volume causes an aching, heavy sensation and physically restricts the shoulder’s range of motion.
Radiation therapy, often administered following surgery, also contributes to long-term shoulder dysfunction. Radiation can affect the elasticity of healthy tissues, inducing fibrosis—the hardening and scarring of soft tissues and muscles around the joint. Fibrosis causes the shoulder capsule and chest muscles to tighten, leading to progressive stiffness and chronic pain that may appear months or years after treatment.
Specialized Musculoskeletal Syndromes
Specific combinations of symptoms and structural changes are recognized as distinct clinical syndromes following breast cancer treatment. These conditions require targeted management.
Axillary Web Syndrome (Cording)
Axillary Web Syndrome (AWS), or cording, is characterized by visible or palpable rope-like structures under the skin. These cords typically start in the armpit and can extend down the arm, sometimes reaching the elbow or wrist. The cords are believed to be inflamed or scarred lymphatic vessels and fibrous tissue resulting from lymph node surgery trauma. AWS causes sharp pain and tightness, severely limiting the ability to raise or extend the arm (abduction). This syndrome can appear days to weeks after surgery, but the prognosis is generally favorable with intervention.
Adhesive Capsulitis (Frozen Shoulder)
Adhesive capsulitis, commonly known as frozen shoulder, involves the progressive loss of both active and passive range of motion. The condition is an inflammation and thickening of the connective tissue capsule surrounding the joint. It often develops because of prolonged immobilization or disuse of the arm following surgery. The condition typically progresses through three stages: the “freezing” phase (increasing pain and decreasing motion); the “frozen” phase (less pain but pronounced stiffness); and the “thawing” phase (motion slowly returns). The severe stiffness makes simple tasks like dressing or reaching overhead difficult.
Post-Mastectomy Pain Syndrome (PMPS)
Post-Mastectomy Pain Syndrome (PMPS) is a persistent neuropathic condition, defined as chronic pain lasting at least three months after surgery. It can occur after any breast surgery, including lumpectomy and lymph node procedures. PMPS is primarily caused by damage to peripheral nerves, resulting in symptoms distinct from typical musculoskeletal pain. The pain is frequently described as burning, shooting, stabbing, or tingling in the chest wall, armpit, or arm, sometimes accompanied by intense itching or numbness. This nerve-specific pain often does not respond well to standard over-the-counter pain relievers.
Comprehensive Management and Rehabilitation
Accurate diagnosis is paramount, beginning with a thorough physical examination and detailed pain history. Diagnostic imaging, such as X-rays, MRI, or CT scans, is used to rule out bone metastasis, especially if the discomfort is deep and constant. For musculoskeletal issues, a physical therapy evaluation pinpoints the exact structures involved, such as scar tissue or nerve irritation.
Physical therapy (PT) and occupational therapy (OT) are the primary interventions for restoring function and reducing pain. PT involves manual techniques, including soft tissue and joint mobilization, to improve tissue elasticity and joint mechanics. For conditions like cording, specific stretching and manual therapy gently lengthen the fibrous bands and restore full arm elevation.
Patients experiencing lymphedema benefit from specialized techniques like manual lymphatic drainage, a gentle massage that helps reroute fluid away from the affected limb. Therapeutic exercises are customized to strengthen weakened muscles, improve posture, and regain range of motion.
For neuropathic pain like PMPS, medical management may include nerve blocks or specific medications, such as anti-epileptics or certain antidepressants, effective for nerve-related discomfort. Self-care strategies, including maintaining proper posture, using heat or cold packs, and performing prescribed home exercises, are integral to long-term rehabilitation.