Characteristics of carpal-tunnel syndrome in the ATAC trial.

Abstract

Abstract Abstract #5085 Introduction: Carpal-tunnel syndrome (CTS) is a condition in which the median nerve is compressed leading to pain and muscle weakness in fingers and the hand. Oestrogen depletion has been shown to induce CTS, whereas the use of hormone replacement therapy is associated with a resolution of the symptom. Aromatase inhibitors lead to profound oestrogen suppression and therefore might induce CTS in postmenopausal women.
 Methods: The Arimidex Tamoxifen Alone or in Combination (ATAC) trial randomised 9,366 postmenopausal women to anastrozole (1mg/day), tamoxifen (20mg/day) or the combination. Analyses were based on the 100 month median follow-up data in women in the two monotherapy arms who started their allocated treatment (anastrozole=3,092; tamoxifen=3,094). Here, we retrospectively investigate the influence of anastrozole on CTS, clinical outcomes, the relative importance of a range of risk factors for CTS, and examine whether they act differently in the presence of anastrozole treatment.
 Results: During the entire active treatment period, 80 (2.6%) cases of CTS were reported in the anastrozole arm compared with 23 (0.7%) in the tamoxifen arm (OR=3.55 (2.22-5.65), P<0.001). In both treatment arms, the majority of CTS were reported as of mild or moderate severity. Most reports of CTS in the anastrozole arm occurred within 18 months of treatment initiation, but incidence remained elevated compared to the tamoxifen arm for the entire treatment period. Median time to resolution of CTS was 8.4 months and none of the women stopped treatment medication due to this adverse event. 13 women underwent carpal-tunnel release surgery (11 anastrozole (1 in 300) vs. 2 tamoxifen (1 in 1500)). Reports of CTS were significantly increased for women who used prior hormone replacement therapy (HRT) (2.3% vs. 1.3%, OR=1.72 (1.16-2.54), P=0.007) or prior chemotherapy (2.5% vs. 1.4%, OR=1.73 (1.14-2.62)). Furthermore, women who were aged 60 years or younger at entry were at greater risk of CTS compared with those aged 61 years or older (2.5% vs. 1.2%, OR=0.48 (0.30-0.76), P=0.002). Body mass index (BMI), hormone receptor status, smoking status, and prior radiotherapy were not found to be risk factors for the development of CTS. When analyses were restricted to only women receiving anastrozole, the same risk factors were identified.
 Conclusions: Although the use of anastrozole is clearly associated with a greater incidence of CTS, it is rare and most cases were of mild severity and short duration and did not lead to treatment discontinuation or surgical intervention. Thus, while CTS can be quite debilitating for the few patients who have severe symptoms, this side effect has minimal impact on the overall risk-benefit ratio for the use of anastrozole in postmenopausal women. Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 5085.