A Dutch retrospective cohort study (2004-2006) investigated the risk of cancer in 13,200 patients with psoriasis or eczema after a median duration of topical coal tar use of 6 months (range 1-300 months). Patients with coal tar treatment were compared with a reference category of patients treated with topical corticosteroids (assumed to pose no increased carcinogenic risk). Coal tar did not increase the risk of non-skin malignancies as evidenced by a hazard ratio (HR) of 0.92; the risk of skin cancer was similarly not significantly increased (HR: 1.09). Prolonged treatment with coal tar in patients with psoriasis or eczema does not therefore appear to be associated with increased carcinogenic risk (Roelofzem, ...