Individual variations in serum melatonin levels through time: implications for epidemiologic studies.

Area of Science:

• Endocrinology
• Cancer Epidemiology
• Chronobiology

Background:

• Melatonin, a circadian rhythm marker, is investigated for anti-cancer properties.
• Circadian rhythm disruption is a potential carcinogenic factor.
• Understanding melatonin variability is crucial for epidemiological studies on cancer.

Purpose of the Study:

• To assess the stability of serum melatonin levels over time.
• To identify lifestyle and environmental factors influencing serum melatonin levels.
• To inform the design of epidemiological studies investigating melatonin and cancer risk.

Main Methods:

• Longitudinal measurement of serum melatonin in 97 men over five years.
• Cross-sectional analysis of serum melatonin in 292 individuals.
• Statistical analysis including Pearson correlation and Analysis of Variance (ANOVA).

Main Results:

• High correlation (0.70) of serum melatonin levels over five years.
• Serum melatonin levels were higher in winter (6.36±0.59 pg/ml) than summer (4.83±0.62 pg/ml).
• Current smokers had significantly lower serum melatonin levels (3.02±1.25 pg/ml) compared to never (6.66±0.66 pg/ml) and former smokers (5.59±0.50 pg/ml).

Conclusions:

• Single serum melatonin measurements may be sufficient for population-level cancer risk studies.
• Season of sample collection and smoking status are important confounders in melatonin research.
• Accurate assessment of melatonin's role in cancer requires accounting for individual and environmental factors.