Shoulder pain is a common experience for many people, often stemming from everyday activities or minor injuries. While most instances of shoulder discomfort are not serious, there are specific situations where it can indicate an underlying medical condition, including breast cancer. It is important to understand that breast cancer does not typically present with shoulder pain as its primary symptom. However, in certain circumstances, this pain can be a manifestation of the disease or its treatment. This article explores the connections between breast cancer and shoulder pain, along with other common causes of shoulder discomfort.
Mechanisms of Shoulder Pain from Breast Cancer
Breast cancer can lead to shoulder pain through several pathways.
Metastasis
Cancer cells can spread from the breast to other parts of the body, including bones in the shoulder area such as the humerus, scapula, clavicle, or spine. When cancer establishes itself in these bones, it can cause a deep, throbbing ache that may worsen at night or with rest.
Lymphedema
This condition involves fluid accumulation due to lymphatic system damage. Breast cancer treatments, like lymph node removal surgery and radiation therapy, can disrupt lymphatic drainage. Fluid buildup typically occurs in the arm and hand but can extend to the shoulder, causing swelling, heaviness, and pain. Up to 70% of women with lymphedema may experience shoulder pain.
Nerve Compression
A tumor in the breast or enlarged lymph nodes in the armpit can press on nerves extending into the shoulder and arm. This pressure can result in referred pain, which is pain felt in an area different from its origin, along with sensations like numbness or tingling in the affected limb.
Treatment Side Effects
Post-surgical scar tissue can restrict movement and cause discomfort. Radiation therapy may lead to fibrosis, a thickening and scarring of tissues affecting shoulder muscles and joints. Certain chemotherapy drugs can induce musculoskeletal pain or neuropathy, a type of nerve damage that can manifest as pain, burning, or tingling sensations in the extremities, including the shoulder and arm. Post-mastectomy pain syndrome, a chronic nerve pain, affects individuals after breast cancer surgery, often causing pain in the chest wall, armpit, and upper arm.
Common Non-Cancer Causes of Shoulder Pain
Musculoskeletal Conditions
Most shoulder pain is not cancer-related, stemming instead from musculoskeletal issues or injuries. Common culprits include rotator cuff injuries, such as tendinitis or muscle tears. Bursitis and frozen shoulder (adhesive capsulitis) are also frequent. Arthritis, including osteoarthritis and rheumatoid arthritis, can cause chronic shoulder pain and stiffness.
Overuse and Acute Injuries
Repetitive movements in occupations or sports can strain shoulder tissues, leading to tendinitis or impingement. Sudden trauma, like falls or impacts, can result in dislocations, fractures, or muscle strains.
Referred Pain
Shoulder pain can sometimes originate elsewhere in the body. Neck problems, such as cervical radiculopathy, can send pain signals to the shoulder and arm. Less commonly, certain internal organ conditions, like heart issues or problems with the liver or gallbladder, may also present as referred shoulder pain.
Recognizing Signs of Cancer-Related Shoulder Pain
Distinguishing cancer-related shoulder pain involves observing specific characteristics and accompanying symptoms.
Pain Characteristics
Cancer-related shoulder pain is often persistent and worsens over time. It typically does not improve with rest, standard pain relievers, or physical therapy, and may intensify at night. The pain often feels deep, aching, or throbbing, rather than sharp or superficial.
Breast Changes
Significant indicators include new lumps or masses in the breast or armpit. Also, look for changes in breast size, shape, skin alterations like dimpling, redness, or thickening. Nipple discharge or changes in nipple appearance are also important signs.
Systemic Symptoms
Other symptoms that may accompany cancer-related shoulder pain include unexplained weight loss, persistent fatigue, or unexplained fever and night sweats. Swelling in the arm, indicating lymphedema, particularly on the same side as the painful shoulder, is another relevant symptom. Cancer-related shoulder pain is often unilateral, meaning it affects only one shoulder, especially on the same side as a breast concern.
When to Consult a Doctor
Consult a medical professional for any new or persistent shoulder pain, especially if it does not improve with rest or conservative measures. Prompt medical evaluation is particularly important if the shoulder pain is accompanied by any of the “red flag” symptoms. These include changes in breast appearance, such as new lumps, skin alterations, or nipple discharge.
Seeking medical attention is also recommended if the shoulder pain is accompanied by systemic symptoms like unexplained weight loss, persistent fatigue, or unexplained fever. Any swelling in the arm, especially on the same side as the painful shoulder, warrants a doctor’s visit. For individuals with a history of breast cancer, any new or worsening shoulder pain should prompt an immediate medical review, as it could indicate recurrence or metastasis.