General
and unspecific damping by malignancy of the
circadian amplitude of circulating human melatonin? Brunetto Tarquini, Germaine Cornélissen,
Roberto Tarquini,
Federico Perfetto & Franz Halberg
Abstract
The circadian rhythm of serum melatonin of 39 cancer patients
is compared with that of 28 healthy subjects matched by gender
and age. Each subject provided 6 blood samples at 4-hour intervals
for determination of melatonin by RIA. After log10-transformation,
data series were analyzed by single and population-mean cosinor
and compared between the two groups and among patients subgrouped
by cancer site, stage and treatment. A circadian rhythm (P<0.001)
is demonstrated for both groups, with a contributing 12-hour
harmonic (P<0.001). In the absence of a difference in MESOR,
the circadian amplitude of the cancer patients is smaller than
that of the healthy subjects (P=0.003). Numerically, nocturnal
(00:00 and 04:00) melatonin concentrations are lower and daytime
(08:00-20:00) melatonin concentrations are higher in the cancer
patients than in the healthy subjects (P=0.032 at 12:00 and
P=0.058 at 16:00). In the age ranges examined, no differences
are found with age in either group or by gender in health. No
differences are found among cancer patients subgrouped either
by site, stage (localized vs. metastasized) or treatment. If
these results are validated, other Janus-like (two-faced: stimulation
or inhibition, depending on chronome stage) effects of malignancy
should be taken into consideration for screening and for timing
treatment.
