In this retrospective, nation-wide cohort study, the risk of cancer was ass
essed for 1738 Danish patients with psoriasis subjected to climatotherapy a
t the Dead Sea during 1972-93, by linkage to the Danish Cancer Registry. Th
e overall risk of cancer in patients treated at the Dead Sea (standardized
incidence ratio, SIR = 1.59) was higher than that expected in the general p
opulation, owing to an excess risk of non-melanoma skin cancer (NMSC) [SIR
= 4.2 for basal cell carcinoma (BCC) and 10.7 for squamous cell carcinoma (
SCC)]. In addition, the distribution of NMSC among body sites, age groups a
nd sexes was unusual in those treated at the Dead Sea, favouring NMSC in yo
ung individuals and at multiple sites (SIR = 10.7 for BCC and 57.2 for SCC)
, multiple BCCs being particularly common among young women, Thus, people s
ubjected to climatotherapy at the Dead Sea for psoriasis constitute a high-
risk group for NMSC, SCC in particular, but not for malignant diseases in g
eneral, The study design precludes conclusions on whether climatotherapy pl
ays a specific part in skin carcinogenesis which is different from other so
urces of ultraviolet (UV) radiation, as climatotherapy is inevitably confou
nded by excess UV exposure.