Abstract
Background/Objectives: Insomnia is associated with immune function. This study evaluated the association between insomnia and febrile neutropenia in women treated with adjuvant chemotherapy for breast cancer. Methods: This secondary analysis used data from the Canadian Cancer Trial Group MA.21 trial, which compared three chemotherapy regimens (CEF, EC/T dose-dense, or AC/T) in 2104 women with high-risk locoregional breast cancer. A total of 1731 patients completed the EORTC QLQ-C30 questionnaire. We compared "insomnia patients" with patients considered "good sleepers" based on the sleep item of this questionnaire. The primary endpoint was the occurrence of febrile neutropenia. Secondary endpoints were the occurrences of leucopenia and infection. Chemotherapy dose reduction was added as a secondary outcome in an unplanned analysis. Results: Patients with insomnia (16.3%) had a significantly higher rate of febrile neutropenia than good sleepers (12.2%; p = 0.01). After controlling for various confounders, the contribution of insomnia in explaining febrile neutropenia remained statistically significant (OR 1.45, 95% CI 1.07-1.97, p = 0.02). Chemotherapy dose reductions were significantly more frequent in patients with insomnia (30.6%) than in good sleepers (21.8%; p < 0.0001). The relationship remained significant in the multivariate analysis (OR 1.67, 95% CI 1.30-2.15, p < 0.0001). Conclusions: In the MA21 trial, insomnia was associated with febrile neutropenia. Furthermore, chemotherapy dose reductions were more common in women with insomnia. These results suggest that the role of insomnia in potential cancer outcomes needs to be confirmed in other studies, given the possible implication of dose reductions on the prognosis of women receiving chemotherapy for breast cancer.