Circadian periodicity of plasma 17-hydroxycorticosteroids in advanced breast cancer.

Circadian periodicity of plasma 17-hydroxycorticosteroids (17-OHCS) was studied in ten patients with advanced breast cancer and ten healthy volunteers. A marked rhythm in plasma 17-OHCS concentration was noticed in normal controls; the maximum concentration occurred at 0800 hr followed by a consistent decline throughout the daytime, reaching a minimum at 0000 hr. The circadian rhythm of plasma 17-OHCS was found to be deranged in six of the patients with breast cancer, but a normal rhythmic pattern was seen in the remaining four patients, although the values remained elevated at all time points of the 24-hr cycle in the patients with breast cancer compared to the healthy volunteers. The normal and altered plasma 17-OHCS rhythms in the patients presumably could be due to individual susceptibility and response to the pathophysiological stress of cancer.