Association of Fat Body Mass With Vertebral Fractures in Postmenopausal Women With Early Breast Cancer Undergoing Adjuvant Aromatase Inhibitor Therapy.

Importance: Aromatase inhibitors induce a profound depletion in serum estrogen levels. Postmenopausal obese women receiving aromatase inhibitor therapy may be at increased risk of bone fractures owing to the detrimental association of adiposity with bone quality and the loss of the protective effect of estrogens on bone mineral density. Objective: To determine whether fat body mass (FBM), as measured by dual-energy x-ray absorptiometry, is associated with vertebral fracture prevalence in postmenopausal women undergoing adjuvant aromatase inhibitor therapy for breast cancer. Design, Setting, and Participants: In this single-center, cross-sectional study, 556 postmenopausal women with early-stage breast cancer were consecutively enrolled from October 15, 2013, to June 30, 2018, and stratified according to whether they were aromatase inhibitor-naive or aromatase inhibitor-treated for at least 2 years. The database was locked on December 31, 2018, and data analysis was completed on February 28, 2019. Eligible patients in both groups had normal renal function, no metabolic diseases, and no previous or current treatment with antiosteoporotic drugs or glucocorticoids. Previous chemotherapy, but not tamoxifen, was permitted. Data were gathered once, at baseline. Main Outcomes and Measures: Vertebral fracture prevalence associated with FBM in aromatase inhibitor-naive and aromatase inhibitor-treated patients. Results: Of the 556 women enrolled, the mean age was 63.0 years (95% CI, 62.2-63.8 years). The 195 aromatase inhibitor-treated patients were older than the 361 aromatase inhibitor-naive patients (mean age, 66.1 vs 61.3 years; P < .001), had a higher body mass index (mean, 26.4 vs 25.3; P = .009), were less likely to engage in physical activity (65.3% vs 73.7%; P = .03), and were less likely to consume alcoholic beverages (68.4% vs 80.9%; P = .001). Among the aromatase inhibitor-naive patients, the vertebral fracture prevalence was higher in the subgroup with FBM below the median value than in those with high FBM, but the difference was not statistically significant (19.2% vs 13.3%; P = .13). Conversely, the proportion of vertebral fractures in the aromatase inhibitor-treated group was 20.0% in patients with low FBM vs 33.3% in patients with high FBM (P = .04). An opposite trend in the association of FBM with vertebral fracture prevalence according to aromatase inhibitor group was shown by multivariable analysis in the propensity score-matched sample: odds ratio, 0.38 (95% CI, 0.12-1.19) and 1.94 (95% CI, 0.67-5.64) in the aromatase inhibitor-naive and aromatase inhibitor-treated groups, respectively (odds ratio for the interaction, 5.77 [95% CI, 1.08-30.81]; P for interaction term = .03). Conclusions and Relevance: Fat body mass may be associated with fragility-related fractures in patients with breast cancer who undergo aromatase inhibitor therapy. If these data are confirmed, obesity could be included in the algorithm for assessing fracture risk and selecting patients to receive bone resorption inhibitors.

Amiloride Is Effective in the Management of Abiraterone-Induced Mineralocorticoid Excess Syndrome without Interfering with Its Antineoplastic Activity.

BACKGROUND: The administration of abiraterone acetate (abiraterone) leads to an adrenocorticotropic hormone (ACTH)-driven increase in mineralocorticoid hormones, requiring glucocorticoid supplementation that may stimulate the growth of prostate cancer (PCa). Amiloride is a drug that selectively reduces the aldosterone-sensitive Na+/K+ exchange and could be effective in the management of mineralocorticoid excess syndrome (MCES). METHODS: The efficacy of amiloride + hydrochlorothiazide (HCT) in the clinical management of abiraterone-induced MCES was assessed in 5 consecutive patients with castration-resistant PCa (CRPC). Then, using the in vitro experimental model of PCa cell lines, the possible effects of drugs usually used in the clinical management of CRPC patients on PCa cell viability were investigated. RESULTS: Amiloride/HCT led to a complete disappearance of all clinical and biochemical signs of abiraterone-induced MCES in the 5 treated patients. The in vitro study showed that abiraterone treatment significantly decreased cell viability of both androgen receptor (AR)-expressing VCaP (vertebral-cancer of the prostate) and LNCaP (lymph node carcinoma of the prostate) cells, with no effect on AR-negative PC-3 cells. Prednisolone, spironolactone, and eplerenone increased LNCaP cell viability, while amiloride reduced it. The non-steroid aldosterone antagonist PF-03882845 did not modify PCa cell viability. CONCLUSIONS: The combination of amiloride/HCT was effective in the management of abiraterone-induced MCES. Amiloride did not negatively interfere with the abiraterone inhibition of PCa cell viability in vitro.