ABSTRACT
Epidemiologists look back to factors from the past that can perhaps help explain present time diseases and other morbid conditions. They are directed to the past since it holds clues to present causes of morbidity and mortality. Hippocrates was actually the first epidemiologist to conduct retrospective studies; he insisted on close observation of the disease experience with attention to preceding environmental conditions that may have disturbed the body’s humoural balance. Retrospective studies began appearing in the professional literature about 1920, when epidemiologists explored the relationship between breast cancer and prior reproductive factors. By the mid-twentieth century, retrospective study design became the preferred method of cancer researchers.
