11/21/2023
Another good article from Healthy Street.
🔈 FROZEN SHOULDER AND RISK OF CANCER - A POPULATION-BASED COHORT STUDY
Frozen shoulder, also called adhesive capsulitis, is characterised by stiffness and pain in the shoulder joint due to inflammation of the synovial lining and capsule. The aetiology of frozen shoulder is not fully understood. It can develop after a shoulder has been immobilised. An increased incidence of frozen shoulder was observed in diabetes vs non-diabetes patients and in patients with diseases such as thyroid and Parkinson’s disease, chronic obstructive pulmonary disease (COPD), and myocardial infarction (MI). Frozen shoulder can last for up to 3 years, and resolves spontaneously in most cases.
Frozen shoulder can be a musculoskeletal manifesting of solid tumours and haematological malignancies and may also represent a misdiagnosed shoulder tumour. In addition, frozen shoulder is a frequent complication after mastectomy due to breast cancer.
Thus, there is some clinical evidence, based on case reports and small cross-sectional studies, that patients with malignancies are at increased risk of frozen shoulder. Scientists examined the association between frozen shoulder diagnosis and subsequent risk of cancer using linked data from Danish population registries.
THE RESEARCH EXPLAINED
Scientists found a slightly increased risk of any cancer diagnosis during the first 6 months following diagnosis of frozen shoulder, while the absolute 6-month risk was 0.70%, thus, 1 out of 142 patients. In particular, there was an association between frozen shoulder and subsequent diagnoses of the lung cancer, breast cancer, and non-Hodgkin’s malignant lymphoma.
The study helped extend the sparse previous research. On the basis of 60 patients, reported that musculoskeletal lesions can follow a cancer diagnosis with frozen shoulder occurring in 20% of patients with solid cancers and 7% of patients with haematological cancers within a mean follow-up time of 3 years. Scientists also observed seven cases (8%) of frozen shoulder within 30 days after surgery among 89 patients with modified radical mastectomy. Researchers also reported frozen shoulder as the only symptom of gallbladder cancer in the case of a 35-year-old woman, suggesting that a skeletal condition may be the initial symptom of a cancer (a marker of occult cancer) rather than a complication of cancer. This is important to consider since cancer in the shoulder can be misdiagnosed as a frozen shoulder.
A possible mechanism underlying the association between lung cancer and frozen shoulder is direct invasion of the cancer into the shoulder joint or peripheral nerves. This is supported by the data showing that 72% of lung cancers were diagnosed at stage III or IV. Direct invasion could occur in particular for apical lung cancer, presenting with rapid onset of clinical symptoms and pleuritic pain due to neurovascular compromise at the level of the superior thoracic aperture. These symptoms might be mistaken for frozen shoulder. Primary treatment for pain symptoms and frozen shoulder can cause delay in reaching a correct cancer diagnosis, and thus negatively influence prognosis.
Synovial reaction of extra-articular bone and capsular carcinomatosis also could explain the association between lung and breast cancer and frozen shoulder. Physicians and surgeons should be open to differential diagnoses if initial treatment of a frozen shoulder is ineffective, including the possibility of lung or breast cancer. Increased risk of cancer diagnosis following frozen shoulder could also be due to diagnostic heightening, since SIR was highest for patients with frequent contacts to the hospital. In addition, frozen shoulder patients undergo shoulder radiographs, which also visualise part of the lungs. This might increase the probability of lung cancer detection.
In conclusion, the scientists found an association between frozen shoulder and a subsequent risk of cancer diagnosis. Thus, frozen shoulder might be an early predictor of cancer. However, the absolute cumulative risk of cancer is too small to recommend screening of frozen shoulder patients in order to find occult cancer.
Reference: British Journal of Cancer