Background:
Melatonin is a biomarker of the central circadian clock and its chronobiotic actions entraining
circadian rhythms to the light-dark cycle are well known. Reduction in melatonin levels and altered circadian rhythms have
been associated with a high risk of breast cancer. Melatonin has also shown to display anti-proliferative effects on breast
cancer growth and proliferation. Evaluation of melatonin circadian rhythm alterations in patients bearing breast cancer may
have interesting prognostic and therapeutic applications.
Objective:
To review studies evaluating the circadian rhythm of melatonin in breast cancer patients. The effects of surgery
and chemotherapy on melatonin secretion were also reviewed.
Methods:
Electronic databases including PubMed/MEDLINE and Scopus were searched from their inception to May 2020,
using the keywords "Melatonin", "Circadian rhythm" and "Breast cancer".
Result:
Patients with breast cancer maintain a circadian rhythm of melatonin secretion with relatively high levels during the
night, and low levels during the day however a reduction of nocturnal melatonin peak and decreased amplitude of melatonin
circadian rhythms in these patients have been also reported. Melatonin levels can influence estrogen receptor concentrations
in hormone-dependent estrogen-positive breast cancer. Chemotherapy alters melatonin levels, and breast surgery tends to
alter melatonin secretion at first day post-operation. Melatonin levels correlate with clinical and psychological symptoms of
breast cancer, such as sleep quality and depression severity.
Conclusion:
Circadian rhythm and the concentration of melatonin in blood are altered in patients with breast cancers and it
can modify not only sleep-wake cycle and thus patients’ quality of life but due to melatonin’s antioxidant effects is can
modulated the effect of therapies. Due to the heterogonous protocols used to assess melatonin and variable environmental
factors during sampling, further studies need to control such variables in order to tailor clinical trial based on melatonin
rhythm adjustment and/or supplementation in breast cancer patients.
Application of New Dressing to Post-operation Skin Flap Necrosis in Breast Cancer Patients Damlms Scot and Vibas Cross
