Hypothesis:  working night shifts long hours, lack of solar light and exposure to industrial light as possible factors of risk for breast and prostate cancer. Their theory suggests that exposure to light at night causes a suppression of the melatonin levels have a direct impact on developing cancer.

Question: Compose an editorial opinion in which you propose a prospective cohort study that should be undertaken to further investigate the association between night shift work and cancer. Briefly describe how you would conduct a cohort study to provide additional evidence for this hypothesis. (steps of cohort)