AB1290 VITAMIN D AND PAIN SYNDROME IN BREAST CANCER PATIENTS TREATED WITH ADJUVANT LETROZOLE

Background: The third-generation aromatase inhibitors (AIs) have shown a favorable overall risk–benefit profile in the upfront adjuvant therapy of postmenopausal estrogen receptor–positive breast cancer. Breast cancer patients treated with long term AIs experience arthralgias and musculoskeletal aching often described as bone pain, musculoskeletal disorder, arthralgia. Objectives: The purpose of this study was to investigate clinical, serological and anamnestic features associated to the joint pain syndrome in non-metastatic breast cancer patients treated with adjuvant AIs. Methods: Between June 2017 and December 2017 patients with early stage estrogen receptor–positive breast carcinomas treated with adjuvant letrozole, attending our Rheumatologic clinic to undergo osteoporosis screening, were included. Pre-existing symptoms and clinical, serological and imaging features were evaluated to assess the type of musculoskeletal disorder. Results: Among 64 patients included a musculoskeletal syndrome was detected in 46 patients (71.8%), whereas diffuse muscle pain was observed in 42 (65.6%) patients, and 83.3% of them had associated arthritis. Serological, imaging and clinical findings suggested more frequently a seronegative arthritis, whereas few patients developed rheumatoid arthritis and arthritis secondary to a connective tissue disease. A direct correlation between pre-existing autoimmune disease and pain symptoms before cancer diagnosis and risk of developing arthritis under AI therapy was observed. Mean vitamin D levels were significantly lower in patients with diffuse myalgia compared to patients with no diffuse myalgia (11.2±5.8 versus 29.5±10.8 ng/ml; t-test p Conclusion: The etiology of AI-associated pain syndrome remain unknown, but clinical, serological, imaging data may be useful to identify the true origin of the musculoskeletal syndrome, as well as a detailed anamnestic history may be useful to identify autoimmune predisposing factors. Myalgias and generalized weakness are likely associated with hypovitaminosis D and might be misdiagnosed as fibromyalgia. The management of these patients should become a multispecialistic task. References [1] Beckwee D, Leysen L. Prevalence of aromatase inhibitor-induced arthralgia in breast cancer: a systematic review and meta-analysis. Support Care Cancer 2017 May;25(5):1673-1686. [2] Borrie AE,Kim RB. Molecular basis of aromatase inhibitor associated arthralgia: known and potential candidate genes and associated biomarkers. Expert Opin Drug Metb Toxicol. 2017 Feb;13(2):149-156. Disclosure of Interests: Stefania Sciacca: None declared, Nadia Melillo: None declared, Francesco Paolo Cantatore Speakers bureau: PFIZER, ROCHE