Shoulder Pain in Breast Cancer: Post-Treatment Concerns

Shoulder pain is a common but often overlooked issue for breast cancer survivors, particularly after surgery, radiation, or other treatments. This discomfort can affect daily activities and quality of life, making it important to recognize potential causes and seek appropriate management.

Musculoskeletal Alterations After Treatment

Breast cancer treatments, particularly surgery and radiation, can lead to significant changes in the musculoskeletal system, often manifesting as shoulder pain and restricted mobility. Surgical procedures such as mastectomy or lumpectomy frequently involve the removal of breast tissue, lymph nodes, and portions of the pectoral muscles, disrupting the shoulder girdle’s structural integrity. This may lead to compensatory movement patterns, straining the rotator cuff and scapular stabilizers. Over time, these altered biomechanics can contribute to adhesive capsulitis (frozen shoulder) or rotator cuff tendinopathy, both commonly reported in breast cancer survivors.

Radiation therapy compounds these changes by inducing fibrosis in surrounding soft tissues. Fibrotic changes in the pectoral muscles and axillary region reduce flexibility and increase stiffness, limiting shoulder joint mobility. A study in Breast Cancer Research and Treatment (2021) found that up to 68% of patients who underwent radiation therapy experienced some degree of shoulder dysfunction, with symptoms persisting for months or even years. Radiation-induced fibrosis can also lead to myofascial pain syndrome, where trigger points in affected muscles cause localized tenderness and referred pain into the upper arm and neck.

Post-surgical scarring and soft tissue adhesions further exacerbate musculoskeletal dysfunction. Scar tissue in the axillary region following lymph node dissection can restrict normal shoulder movement, leading to compensatory overuse of the deltoid and trapezius muscles. This increases the risk of secondary issues such as impingement syndrome. A systematic review in The Journal of Cancer Survivorship (2022) found that nearly 50% of breast cancer survivors report persistent shoulder pain linked to post-surgical adhesions, highlighting the lasting impact of these structural changes.

Lymphatic System Changes

Disruptions to the lymphatic system are a frequent consequence of breast cancer treatment, particularly when surgery or radiation affects the axillary lymph nodes. Lymph node dissection can compromise normal drainage, leading to fluid accumulation in the upper extremity. This increases the likelihood of lymphedema, a chronic condition characterized by swelling, heaviness, and discomfort in the arm and shoulder. Individuals who undergo axillary lymph node dissection face a 15-30% risk of developing lymphedema, with symptoms sometimes appearing years after treatment. The resulting swelling places additional strain on the shoulder joint, exacerbating stiffness and limiting mobility.

Radiation therapy can worsen lymphatic disruptions by inducing fibrosis in lymphatic vessels and surrounding tissues, obstructing lymph flow and increasing interstitial fluid pressure. This chronic low-grade inflammation has been linked to increased connective tissue deposition, which further restricts shoulder movement. A 2023 study in Cancer Rehabilitation found that breast cancer survivors with radiation-induced fibrosis were more likely to experience shoulder pain and functional impairments, with a 40% reduction in shoulder abduction and flexion.

The interplay between lymphedema and musculoskeletal adaptations can create a cycle of discomfort and restriction. As swelling increases, patients may unconsciously alter posture and movement patterns to minimize pain, leading to muscle imbalances that place additional stress on the shoulder girdle. This compensatory movement often results in scapular dyskinesis, where the normal rhythm of scapular motion is disrupted. Over time, these changes can contribute to chronic pain syndromes, making early intervention strategies such as manual lymphatic drainage and therapeutic exercise essential for maintaining shoulder function.

Diagnostic Ultrasound And Other Imaging

Accurately identifying the causes of shoulder pain in breast cancer survivors requires imaging techniques that assess soft tissue and structural abnormalities. Various modalities, including ultrasound, magnetic resonance imaging (MRI), and X-ray, provide valuable insights into musculoskeletal changes, lymphatic complications, and nerve involvement. The choice of imaging depends on specific symptoms and clinical presentation.

Ultrasound

Ultrasound is a widely used tool for evaluating soft tissue abnormalities in the shoulder, particularly in individuals with post-treatment complications. It effectively detects rotator cuff tears, tendon inflammation, and fluid accumulation, which are common due to altered biomechanics and lymphedema. A 2022 study in The Journal of Ultrasound in Medicine found that ultrasound had an 89% sensitivity in identifying rotator cuff pathology in post-mastectomy patients, making it a reliable first-line diagnostic tool. Additionally, ultrasound-guided assessments can help detect myofascial trigger points and fibrotic changes in the pectoral and axillary regions, which may contribute to restricted movement and pain. Unlike MRI or X-ray, ultrasound allows for dynamic imaging, enabling clinicians to assess shoulder function in real time. This is particularly useful for identifying impingement syndromes and abnormal scapular motion patterns that may not be evident in static imaging.

Magnetic Resonance Imaging

MRI provides a detailed evaluation of soft tissue and joint structures, making it useful for assessing post-treatment complications such as adhesive capsulitis, radiation-induced fibrosis, and brachial plexus involvement. This imaging modality offers high-resolution visualization of muscles, tendons, and ligaments, allowing for the detection of subtle changes contributing to persistent shoulder pain. A 2023 review in European Radiology highlighted that MRI is the preferred method for diagnosing radiation-induced fibrosis, as it can differentiate between fibrotic tissue and recurrent malignancy. Additionally, MRI with contrast enhancement can assess vascular and lymphatic changes, providing insights into lymphedema-related complications. While highly informative, MRI is often reserved for cases where ultrasound findings are inconclusive or when nerve involvement is suspected, as it can detect nerve compression or inflammation that may contribute to neuropathic pain.

X-Ray

X-ray imaging primarily evaluates bony structures and detects conditions such as osteoarthritis, fractures, or postural abnormalities that may contribute to shoulder pain. While it does not provide detailed visualization of soft tissues, X-ray can identify skeletal changes resulting from altered biomechanics post-treatment. A study in Skeletal Radiology (2021) found that breast cancer survivors with chronic shoulder pain often exhibited acromioclavicular joint degeneration, likely due to compensatory movement patterns following surgery or radiation. Additionally, X-ray can assess clavicular or scapular malalignment, which may develop due to prolonged postural adaptations. Although not the primary imaging choice for soft tissue evaluation, X-ray remains a valuable tool for ruling out structural abnormalities that may exacerbate musculoskeletal dysfunction.

Specific Nerve Involvement

Nerve-related shoulder pain in breast cancer survivors often stems from surgical interventions, radiation therapy, or prolonged postural adaptations that place stress on the peripheral nervous system. The brachial plexus, a complex network of nerves controlling the shoulder, arm, and hand, is particularly susceptible to injury following breast cancer treatment. Surgical procedures involving axillary lymph node dissection or mastectomy can stretch or compress these nerves, leading to neuropathic pain characterized by burning sensations, numbness, or shooting discomfort radiating down the arm. In some cases, intercostobrachial nerve damage, which occurs when sensory nerves near the underarm are disrupted, results in persistent hypersensitivity or deep aching pain that complicates shoulder mobility.

Radiation therapy can also contribute to nerve dysfunction, particularly when the treatment field includes the supraclavicular or axillary regions. Radiation-induced brachial plexopathy occurs when high-dose radiation leads to fibrosis around nerve fibers, causing progressive weakness, sensory deficits, and pain in the affected limb. Unlike musculoskeletal pain, which often improves with movement, nerve-related pain may worsen at night or with specific postures. A case series in Pain Medicine (2022) described patients experiencing delayed-onset neuropathy years after radiation, highlighting the long-term risk of nerve damage even after initial recovery.