Can Cancer Cause Shoulder Pain? When to Be Concerned

Cancer can cause shoulder pain, though it does so far less often than the musculoskeletal injuries, rotator cuff tears, and arthritis that account for the vast majority of sore shoulders. When cancer is the culprit, the pain can arrive through several distinct routes: a tumor growing directly into shoulder structures, cancer that has spread to nearby bone, irritation of the diaphragm sending pain signals up to the shoulder via shared nerve pathways, or even immune reactions triggered by a distant malignancy. Because shoulder pain is so common and so often benign, cancer-related cases are frequently missed or misdiagnosed for months, making it worth understanding which features should prompt a deeper look.

How a Lung Tumor Can Cause Shoulder Pain

The best-known connection between cancer and shoulder pain involves a specific type of lung cancer called a Pancoast tumor, which grows at the very top of the lung. Unlike most lung cancers, a Pancoast tumor sits right next to the brachial plexus, a network of nerves that runs from the neck down through the shoulder and into the arm. Because of that location, the tumor can press on or invade those nerves and produce pain that feels exactly like a shoulder or upper-arm injury. It can also invade the first rib, the vertebrae, and the stellate ganglion, a cluster of nerves near the spine that controls certain functions in the face and eye on the same side.

Pancoast tumors account for roughly 3 to 5 percent of all lung cancers, so they are uncommon even among people diagnosed with lung malignancies.¹ What makes them particularly tricky is that shoulder pain is often the first and most prominent symptom. Because the tumor sits at the lung’s apex, it may not cause a cough, shortness of breath, or anything else that would immediately suggest a lung problem. The pain can radiate down the inner arm toward the ring and pinky fingers, mimicking a pinched nerve in the neck. If the stellate ganglion is involved, you may also notice a drooping eyelid, a smaller pupil, or reduced sweating on one side of the face, a combination known as Horner’s syndrome.² Diagnosis is frequently delayed because the initial complaint looks orthopedic, and chest X-rays can miss these tumors since the lung apex is partly hidden behind the collarbone and first rib.

Cancer That Spreads to the Shoulder

The shoulder girdle, which includes the upper arm bone (humerus), the collarbone, and the shoulder blade, is a common landing site for cancer that has spread from elsewhere in the body. Breast cancer is one of the most frequent culprits: in one surgical series of 93 patients treated for metastatic tumors in the humerus and shoulder girdle, breast cancer was the most common primary source, and the upper humerus was involved in most cases.³ Lung, kidney, and thyroid cancers also frequently send metastases to bone in this region.

A case report described a 46-year-old woman who developed left shoulder pain and limited motion that turned out to be caused by breast cancer metastasizing directly into her shoulder.⁴ The initial assumption was a common orthopedic problem like calcific tendinitis or degenerative arthritis, both of which look similar on a cursory exam. Another case involved a 48-year-old man with chronic bilateral shoulder pain and no history of injury who was eventually found to have advanced multiple myeloma, a blood cancer that had caused a pathologic fracture in his right clavicle.⁵ In both cases, the absence of trauma and the persistence of symptoms despite standard treatments were eventually what prompted the imaging that revealed cancer.

When cancer weakens bone, it also raises the risk of a pathologic fracture, where the bone breaks during a routine activity that would not break healthy bone. Pain from a metastatic deposit tends to be constant rather than activity-dependent, often worsening at night, and it does not improve with rest the way a muscle strain would.

Referred Pain from Below the Shoulder

One of the less intuitive pathways involves the diaphragm, the large muscle sheet separating the chest from the abdomen. The diaphragm is served by the phrenic nerve, which originates from the same spinal cord levels (C3 through C5) that supply sensation to the shoulder. When something irritates the underside of the diaphragm, such as a tumor in the liver pressing upward, the brain can misinterpret the signal as coming from the shoulder. This is called referred pain, and it is the same reason a heart attack can cause arm pain rather than just chest pain.

A case report documented this mechanism in a patient whose shoulder pain was ultimately traced to liver metastases irritating the diaphragm. The pain signals traveled via the phrenic nerve to the C3-5 spinal levels and were perceived as shoulder pain, likely through the supraclavicular nerves or the nerves supplying the shoulder joint itself.⁶ Cancers of the liver, pancreas, and stomach can all produce this kind of referred shoulder pain, usually felt in the right shoulder for liver lesions or the left shoulder for splenic or pancreatic tail lesions. The pain tends to be deep, hard to localize precisely, and unrelated to shoulder movement, which is what distinguishes it from a rotator cuff problem.

Primary Bone Tumors in the Shoulder

While metastatic disease is far more common in adults, primary bone tumors, cancers that originate in the bone itself, can also show up in the shoulder region. This is particularly relevant in younger patients. In one case, a 16-year-old boy presented with left shoulder pain after a fall. Closer questioning revealed the pain had actually started a month before the fall. Early signs of osteosarcoma were visible on the initial X-ray but were missed; it took three more months of persistent symptoms before the diagnosis was made.⁷

A study of pediatric shoulder girdle tumors found that the most common malignant tumor in children and adolescents in this area was osteosarcoma, and the most frequent location was the proximal humerus, the upper end of the arm bone near the shoulder.⁸ Most shoulder girdle tumors in young people are benign, but the presence of persistent, worsening pain that does not respond to rest or anti-inflammatory medication, especially in someone under 25, warrants imaging. A key detail from the osteosarcoma case is worth emphasizing: the pain predated the fall. It is easy for both patients and doctors to attribute bone pain to a minor injury, when in reality the weakened bone may have contributed to the fall or the pain existed independently.

Paraneoplastic Syndromes and Joint Inflammation

Sometimes cancer causes shoulder pain without any tumor being anywhere near the shoulder. Paraneoplastic syndromes are conditions in which the body’s immune response to a cancer produces inflammation in distant joints, muscles, or other tissues. The cancer itself might be in the lung, ovary, or pancreas, but the immune system’s reaction can show up as joint pain, swelling, and stiffness that looks a lot like rheumatoid arthritis or another autoimmune condition.

Several recognized paraneoplastic patterns can affect the shoulder. Hypertrophic osteoarthropathy causes painful swelling of the joints along with a characteristic thickening of the fingertips called clubbing, and it is most often associated with lung cancer. Carcinoma polyarthritis is an inflammatory arthritis that mimics rheumatoid arthritis but tends to come on suddenly, affect joints asymmetrically, and respond poorly to standard rheumatologic treatments.⁹ Other patterns include palmar fasciitis with polyarthritis, which is linked to ovarian and other cancers, and remitting seronegative symmetrical synovitis with pitting edema, which can appear alongside various solid tumors.¹⁰

The hallmark that distinguishes these syndromes from garden-variety arthritis is that they tend to appear abruptly, sometimes in a person over 50 who has never had joint problems before. Diffuse bone pain combined with clubbing of the fingers in someone of that age group is considered a red flag worth investigating for an underlying malignancy.⁹ When the underlying cancer is treated, the joint symptoms often improve or resolve entirely, which further confirms the connection.

Why Cancer-Related Shoulder Pain Gets Misdiagnosed

The fundamental problem is that shoulder pain is extremely common in the general population, and cancer-related shoulder pain does not have a single obvious giveaway. A scoping review of shoulder girdle tumors that were initially misdiagnosed found that the main complaints were shoulder pain and stiffness or loss of range of motion, each present in about 73 percent of cases. Misdiagnosis rates ranged from 10 to 50 percent, and the resulting delays stretched up to 30 months.¹¹ The most common wrong diagnoses were frozen shoulder, rotator cuff disease, and other benign musculoskeletal conditions.

The clinical presentation of shoulder tumors is often nonspecific, with pain as the primary complaint, and a delayed or missed diagnosis can seriously affect treatment options and prognosis.¹² Part of the issue is that early imaging for shoulder pain usually involves a plain X-ray and sometimes an ultrasound, both of which are designed to look for fractures, dislocations, and soft tissue tears. Small bone lesions from metastases or early primary tumors can be invisible on these studies and only show up on MRI or CT scans, which are not routinely ordered for what appears to be a straightforward orthopedic complaint.

This does not mean you should panic every time your shoulder hurts. The overwhelming majority of shoulder pain has a boring explanation. But the pattern of misdiagnosis is real enough that certain features should lower your threshold for asking harder questions.

When Shoulder Pain Should Raise Concern

No single symptom is a reliable cancer detector, but several features in combination should prompt further investigation. Think of these less as diagnostic criteria and more as reasons to push for more thorough imaging or a specialist referral if initial treatment is not helping.

• Night pain: Pain that wakes you from sleep or intensifies when you are resting is more characteristic of bone lesions or tumors than of muscle or tendon injuries, which generally feel better at rest.
• No clear cause: Shoulder pain that comes on gradually without any injury, overuse, or change in activity level is worth investigating, especially if you are over 50 or have a history of cancer.
• Failure to improve: Shoulder pain from common causes typically responds at least partially to rest, ice, anti-inflammatory medication, and physical therapy within a few weeks. Pain that is unchanged or worsening after 4 to 6 weeks of appropriate treatment warrants further workup.
• Constitutional symptoms: Unexplained weight loss, fatigue, fevers, or night sweats alongside shoulder pain shift the picture toward something systemic rather than local.
• Neurological changes: Weakness, numbness, or tingling radiating down the arm, especially on the inner side toward the pinky finger, can indicate nerve involvement from a Pancoast tumor or other lesion pressing on the brachial plexus.
• Horner’s syndrome: A drooping eyelid, constricted pupil, or absent sweating on one side of the face alongside shoulder pain is a classic Pancoast tumor presentation and warrants urgent imaging.
• Known cancer history: If you have been treated for cancer in the past, new shoulder pain should be evaluated with imaging that can detect bone metastases, even if the cancer was considered cured.

Age and smoking history also matter. In a young person with no risk factors, persistent shoulder pain is more likely to point toward a primary bone tumor if it turns out to be malignant at all. In an older adult who smokes, Pancoast tumor enters the picture. And in anyone with a history of breast, lung, kidney, or prostate cancer, the possibility of metastatic disease to the shoulder girdle is a realistic concern.

Shoulder Pain After Cancer Treatment

It is worth distinguishing pain caused by cancer from pain caused by cancer treatment, because survivors frequently deal with the latter. Breast cancer treatment is a major contributor. Surgery, whether lumpectomy or mastectomy, can alter the mechanics of the shoulder by changing the muscles and tissues of the chest wall. And radiation therapy compounds the problem: it damages the cells responsible for muscle repair, causing cell death both during treatment and years afterward, and it creates conditions that limit the muscle’s ability to recover from atrophy.¹³

The combination of surgical changes and radiation damage means that shoulder dysfunction in breast cancer survivors is common and can persist long after treatment ends. A study of breast cancer survivors found that those with arm and shoulder problems scored significantly worse on quality-of-life measures compared to survivors without those issues, across physical functioning, pain, and emotional well-being domains.¹⁴ Movement restriction in particular had a greater negative impact on quality of life than lymphedema did.

Treatment-related shoulder pain is different from cancer-related shoulder pain in one important way: it tends to track clearly with the timing of surgery or radiation, and the affected shoulder is on the same side as the treated breast. However, the distinction is not always simple. A cancer survivor who develops new shoulder pain on the treated side may have treatment-related dysfunction, a recurrence, or metastatic disease, and only imaging can sort out which it is. If you are a cancer survivor experiencing new or changing shoulder symptoms, that context alone is reason enough to get it checked rather than assuming it is just a lingering side effect.

Shoulder Pain in Children and Teenagers

Shoulder pain in adults is overwhelmingly degenerative or injury-related, and even when cancer is involved, it is usually metastatic disease from a cancer diagnosed elsewhere. In children and adolescents, the calculus shifts. Degenerative shoulder disease is essentially nonexistent in this age group, so persistent shoulder pain without a clear traumatic cause raises different considerations. The most common malignant shoulder tumor in pediatric patients is osteosarcoma, and it most often appears in the proximal humerus, the growth-active end of the upper arm bone near the shoulder.⁸

The tricky part is that teenagers are also the demographic most likely to have sports-related shoulder pain from overuse, growth-plate irritation, or minor injuries. A bone tumor can lurk behind what looks like a sports injury, especially if the tumor weakens the bone enough to make a minor impact more painful than expected. The osteosarcoma case described earlier is a textbook example: the boy attributed his pain to a fall, but the pain had actually started before the fall, and early X-ray changes were missed.⁷ Parents and pediatricians should pay attention when a young person’s shoulder pain does not improve as expected within a few weeks, especially if it is worsening, present at rest, or accompanied by visible swelling.