Fatigue, alopecia and stomatitis among patients with breast cancer receiving cyclin-dependent kinase 4 and 6 inhibitors: a systematic review and meta-analysis.

Cyclin-dependent kinase (CDK) inhibitors emerge as efficacious agents in hormone positive metastatic breast cancer with more acceptable toxicity profiles than cytotoxic chemotherapy. However, some adverse effects such as fatigue, alopecia and stomatitis, vastly concern patients.

The search was conducted in PubMed, American Society of Clinical Oncology meeting library, European Society for Medical Oncology meeting abstract, and the San Antonio meeting abstract databases. We identified phase 2 or 3 trials recruiting patients with breast cancer, randomized to receive hormonal treatment plus either CDK4/6 inhibitors or placebo. We considered studies providing incidence of fatigue, alopecia and stomatitis relevant.

One thousand records were screened. 34 studies were considered relevant. Four studies were found to be eligible for meta-analysis with a total of 2007 patients. The relative risk for all grade fatigue was 1.34 [95% CI: 1.17-1.54, p < 0.0001], for all grade alopecia was 2.14 [95% CI: 1.23-3.73, p = 0.007], and for all grade stomatitis 4.87 [95% CI: 2.11-11.24, p = 0.0002]. In addition, the relative risk for high grade fatigue was 2.40 [95% CI: 1.10-5.26, p = 0.03].

CDK4/6 inhibitors were associated with an increased risk of fatigue, alopecia and stomatitis. Further studies with self-reported questionnaires may elucidate the impact of the increased risk of these selected adverse effects on the patients' quality of life.