Organ transplant recipients taking immunosuppressive drugs are at an estimated 65-fold greater risk of squamous cell carcinoma (SCC) and a 10-fold higher risk of basal cell carcinoma (BCC) (McCann, 1999). Agents used to prevent allograft rejection include cyclosporine or azathioprine, often combined with glucocorticoids. Systemic glucocorticoids alone (e.g., prednisone, prednisolone, dexamethasone and cortisone) are widely used for a variety of medical conditions including connective tissue diseases, musculoskeletal disorders and allergies. However, it is presently unknown whether these patients are at an increased risk of NMSC. Therefore, we examined the potential risks of SCC and BCC associated with glucocorticoid use in non-transplant recipients, as part of a population-based case-control study of NMSC conducted in New Hampshire, USA. MATERIALS AND METHODS Study groupTo identify cases for our study, we enlisted the collaboration of dermatologists and pathology laboratories throughout New Hampshire and bordering regions (Karagas et al, 1999). We selected a random sample of BCC cases (for efficiency) and all cases of invasive SCC diagnosed from July 1, 1993 through June 30, 1995 among New Hampshire residents, aged 25-74 years. The sample of BCC cases was drawn concomitantly with the SCC cases and controls, and stratified on anatomic site, age and gender to ensure representation of the entire group of BCC diagnoses. As of March 1996, we identified 1143 potential participants. One patient was not contacted at the physician's request, 31 (3%) were reported as deceased by a household member or physician, 10 (1%) lived in households in which no one answered after 40 attempts to telephone distributed over days, evenings and weekends, 178 (16%) declined participation and 27 (2%) were deemed mentally incompetent or too ill to take part. We interviewed a total of 603 BCC and 293 SCC cases.We chose controls from New Hampshire residents aged 25-74 years who were frequency-matched on age (25-34, 35-44, 45-54, 55-64, 65-69, 70-74 years) and gender to represent the combined distribution of the SCC and BCC cases. We selected controls (roughly equal in number to the number of BCC cases) from lists of New Hampshire residents provided by the New Hampshire Department of Transportation (for those less than 65 years old) and Health Care Financing Administration's Medicare Program (for those 65 years and older). For interviewing purposes, controls were randomly assigned reference dates comparable to the cases' diagnosis dates. Of the 820 potential controls, 12 (2%) were reported as deceased by a member of the household, for 12 (2%), no one answered in the household after 40 attempts to telephone distributed over days, evenings and weekends, 228 (28%) declined participation and 28 (3%) were deemed mentally incompetent or too ill to take part. We thus interviewed 540 controls for the study. Personal interviewAll participants provided informed consent in accordance with the Committee for the Protection of Human Subjects at Dartmouth ...