Does incidence of breast cancer and prostate cancer decrease with increasing degree of visual impairment.

Area of Science:

• Epidemiology
• Oncology
• Ophthalmology

Background:

• Light at night is hypothesized to influence cancer risk, potentially via melatonin suppression or antioxidant effects.
• Hormone-related cancers, particularly breast cancer, are of interest in relation to light exposure.
• Previous research suggests a link between light at night and increased cancer incidence.

Purpose of the Study:

• To investigate the association between visual impairment and cancer risk.
• To test the hypothesis that blind individuals have a lower risk of developing cancer.
• To explore the role of light at night in cancer development.

Main Methods:

• A follow-up study utilized data from the Finnish Register of Visual Impairment and the Finnish Cancer Registry.
• The study cohort comprised 17,557 individuals with visual impairment.
• Cancer incidence was analyzed for the period 1983-2003.

Main Results:

• A decreased risk of breast cancer was observed in females with increasing degrees of visual impairment.
• A similar, though less consistent, trend was noted for prostate cancer in males.
• Individuals with near-total blindness showed a significantly higher incidence of other cancers compared to the general Finnish population.

Conclusions:

• Findings support epidemiological evidence for reduced hormone-related cancer risk in visually impaired individuals.
• This suggests a potential relationship between exposure to light at night and breast cancer risk.
• The results do not support a general protective effect against cancer due to a lack of visible light.