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Comment & Response
October 2016

Study on the Risk of Cutaneous Squamous Cell Carcinoma After Vismodegib Therapy for Basal Cell Carcinoma—Reply

Author Affiliations
  • 1Department of Dermatology and Urology, Stanford University School of Medicine, Redwood City, California
  • 2Department of Dermatology, Stanford University School of Medicine, Redwood City, California
JAMA Dermatol. 2016;152(10):1173. doi:10.1001/jamadermatol.2016.2429

In Reply We agree with Gjersvik and Puig et al that our study1 is a retrospective cohort study and thank the writers for clarifying this. According to the textbook Epidemiology in Medicine by Hennekens et al,

Considerable confusion has arisen concerning the terms retrospective and prospective as applied to epidemiologic studies. Some investigators have used these terms synonymously with case-control and cohort, respectively, reasoning that the former looks backward from a disease to a possible cause, while the latter looks forward from an exposure to an outcome… While this terminology is theoretically applicable to case-control studies, it has the greatest practical utility for differentiating two main types of cohort studies, i.e. retrospective and prospective cohort studies.2(p23)