The short answer
Almost all shoulder pain is rotator cuff, impingement or arthritis. Pain not reproduced by moving the shoulder, with no injury, night waking and hand or eye signs, needs chest imaging.
Rotator cuff problems, impingement, frozen shoulder, arthritis and referred neck pain account for nearly all shoulder pain.
Mechanical pain is reproduced by movement, tender to press, and improves over weeks with rest and physiotherapy.
Referred pain follows different rules: diaphragm irritation causes shoulder-tip pain, and cardiac pain comes with chest and breathing symptoms.
Pancoast tumours at the lung apex are 3-5% of lung cancers, usually cause no cough, and present with shoulder pain in up to 96% of cases.
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The full explanation.
What shoulder pain usually turns out to be
The overwhelming majority of shoulder pain is mechanical. Rotator cuff tendinopathy and tears, subacromial impingement, adhesive capsulitis (frozen shoulder), osteoarthritis, and pain referred from an arthritic neck account for nearly all of it. These share a recognisable behaviour: the pain is linked to particular movements or positions, it can be reproduced when a clinician moves your arm, it is often tender to press, and it tends to improve over weeks with rest, activity modification and physiotherapy.
Cancer is an uncommon cause of shoulder pain. It appears on this list because when it does cause shoulder pain, the pain behaves differently, and that difference is learnable.
Pain that is referred rather than local
Structures that have nothing to do with the shoulder joint can send pain there.
The diaphragm shares nerve supply with the skin over the tip of the shoulder, so irritation beneath it, from the liver, gallbladder, spleen, an abscess or the lining of the lung, can present as shoulder pain with an entirely normal shoulder examination. Heart problems refer to the left shoulder and arm, usually with chest heaviness, sweating or breathlessness.
The pattern most relevant here comes from the very top of the lung. Tumours in that position, known as Pancoast or superior sulcus tumours, make up about 3% to 5% of lung cancers and typically lack the usual lung cancer symptoms. There is often no cough and no coughing of blood. Shoulder pain is the presenting complaint in up to 96% of cases, which is exactly why these are so often treated first as rotator cuff problems, cervical disc disease or frozen shoulder. Diagnostic delays of five to ten months are documented.
The features that separate it from an injury
Consider raising these specifically if they apply:
- No injury, strain or unaccustomed activity preceded the pain
- The pain is not reproduced by moving the shoulder, and moving it freely does not make it worse
- Pain wakes you at night and does not settle whatever position you take
- The pain is steadily worsening over weeks rather than fluctuating
- Six weeks of physiotherapy or rest have produced no change at all
- Pain radiates to the shoulder blade, armpit or down the inner side of the arm
- Numbness or tingling in the ring and little fingers, or weakness and wasting of the small muscles of the hand
- A drooping eyelid with a smaller pupil on the same side, or reduced sweating on that side of the face
- Hoarseness, breathlessness, unexplained weight loss, or a smoking history
The last two bullets together describe the combination clinicians are taught to take seriously: shoulder pain plus hand symptoms plus eye changes on the same side.
What a workup involves
A thorough assessment examines the shoulder, the neck and the chest, and includes a neurological examination of the arm and hand. Reproducing the pain with shoulder movement points strongly towards a joint or tendon cause; being unable to reproduce it is itself informative.
Imaging usually starts with a plain shoulder X-ray. When the history does not fit an injury, a chest X-ray is added, with the caveat that lesions at the lung apex are notoriously easy to miss because of overlying shadows. CT of the chest is more reliable, and MRI of the thoracic inlet and brachial plexus is the most sensitive test when a superior sulcus tumour or nerve root involvement is suspected. Blood tests may be added when infection or inflammatory disease is possible. Ultrasound or MRI of the shoulder itself assesses rotator cuff structures.
How long is too long to wait
Pain that followed a clear strain, and that changes with position and movement, is reasonable to manage with activity modification and physiotherapy for four to six weeks before reassessment.
Book an appointment sooner if there was no injury at all, if the pain wakes you consistently at night, if it is getting worse each week rather than settling, or if any of the neurological or eye features above have appeared. If you have already had six weeks of treatment with no improvement, it is reasonable to ask specifically whether imaging that includes the chest, not only the shoulder, is warranted.
Seek emergency care for shoulder or arm pain with chest tightness, sweating, nausea or breathlessness, and for shoulder-tip pain with severe abdominal pain, dizziness or fainting.
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Words to know
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Common questions
How do I tell mechanical shoulder pain from referred pain?
Mechanical pain has a movement signature: certain arcs hurt, pressing on the area hurts, and position changes it. Referred pain is largely unaffected by how you move your arm, and a clinician often cannot reproduce it during examination.
Is night pain always a red flag?
No. Rotator cuff problems and frozen shoulder commonly hurt at night, particularly when lying on that side. What is different is pain that wakes you regardless of position, does not ease when you shift, and is getting worse week by week.
I have had physiotherapy for six weeks with no change. What next?
That is a reasonable point to reassess rather than continue. Ask specifically whether the assessment has included your neck, your hand strength and sensation, and whether chest imaging is warranted given there was no injury.
Will a shoulder X-ray or MRI find a lung tumour?
Not reliably. A shoulder X-ray images the joint, and a shoulder MRI images the rotator cuff. An apical lung tumour needs a chest X-ray at minimum, and CT of the chest or MRI of the thoracic inlet to be seen properly.
I have never smoked. Does that rule it out?
It lowers the probability substantially but does not eliminate it. Lung cancers do occur in people who have never smoked. The pattern of the pain, not smoking status alone, drives whether imaging is warranted.
Questions to ask your doctor
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Written by: Cancer Explained Editorial TeamSources last checked: 2026-07-30Last updated: 2026-07-30Next planned review: 2028-07-29
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Cancer Explained does not originate medical claims. Every page restates guidance already published by the National Cancer Institute, the CDC, the USPSTF and the FDA, in plain language, with the source cited so you can check the original yourself. AI does the translating and organizing; automated checks test claims, citations, clarity and safety before anything publishes. We do not employ clinicians and do not intend to — our work is translation and navigation, not clinical judgment. Nothing here is personal medical advice, and no page can account for your particular situation.
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Human medical review: not completed. Cancer Explained is not clinician-reviewed, and that is a deliberate design choice rather than a gap we are waiting to close. We restate published federal guidance and cite it; the authority belongs to the source, not to us. That is why every page names where its claims come from — so you can verify us instead of trusting us. Use it to understand your situation and to ask better questions of the people treating you.
How this page was created
Cancer Explained does not originate medical claims. Every page restates guidance already published by the National Cancer Institute, the CDC, the USPSTF and the FDA, in plain language, with the source cited so you can check the original yourself. AI does the translating and organizing; automated checks test claims, citations, clarity and safety before anything publishes. We do not employ clinicians and do not intend to — our work is translation and navigation, not clinical judgment. Nothing here is personal medical advice, and no page can account for your particular situation.
Editorial status: Source verified — This page was created with AI assistance and checked against the sources listed on it. Source checking is not a medical review.
Human medical review: not completed. Cancer Explained is not clinician-reviewed, and that is a deliberate design choice rather than a gap we are waiting to close. We restate published federal guidance and cite it; the authority belongs to the source, not to us. That is why every page names where its claims come from — so you can verify us instead of trusting us. Use it to understand your situation and to ask better questions of the people treating you.
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