Abstract
B112
Objective: Rare invasive skin cancers such as mixed basal/squamous cell (mixed) carcinomas, Kaposi’s sarcomas, Merkel cell carcinomas, and dermatofibrosarcomas, have poorly defined etiologies. Second primary cancers associated with these skin cancers may provide clues into shared environmental or host risk factors. >Methods: The 2006 update of the Swedish Family-Cancer Database (version VII, MigMed2), which contains data on histologically verified incident cancers diagnosed in the Swedish population (approximately 11.5 million individuals) between 1958 and 2004 was the cohort used for this study. Standardized incidence ratios (SIR) and 95% confidence intervals (CI) were calculated to compare the risk of second primary cancers following a first primary skin cancer to the baseline risk of these primary cancers in a population unaffected by skin cancer. SIRs were also calculated for risk of a second primary skin cancer following all common first primary cancer diagnoses. >Results: 5,405 invasive first primary skin cancers and 892 second primary skin cancers were diagnosed in this cohort, excluding squamous cell carcinomas. Following a mixed skin carcinoma diagnosis, risk was increased for upper aerodigestive tract cancer (SIR=2.00, 95% CI 1.00-3.58), prostate cancer (SIR=1.28, 95% CI 1.00-1.63), skin cancer (SIR=11.45, 95% CI 9.53-13.64) and melanoma (SIR=3.30, 95% CI 1.95-5.22). Similarly, risk of a mixed skin carcinoma was increased following upper aerodigestive tract cancer (SIR=3.57, 95% CI 2.07-5.72) prostate cancer (SIR=1.51, 95% CI 1.11-2.02), skin cancer (SIR=11.38, 95% CI 9.16-13.98), and melanoma (SIR=95% CI 4.61, 3.06-6.67). Mixed skin carcinoma risk was also significantly increased following cancer of the salivary gland, endometrium, and urinary bladder, although these risks were not reciprocated. Following a first primary diagnosis of Kaposi’s sarcoma, risk of skin cancer (13.71, 95% CI 8.86-20.26) and non-Hodgkin’s lymphoma (SIR=8.10, 95% CI 3.86-14.95) was increased, and similarly Kaposi’s sarcoma risk was increased following skin cancer (11.11, 95% CI 7.18-16.42) and non-Hodgkin’s lymphoma (6.90, 95% CI 2.74-14.30). Skin cancer risk was increased following Merkel cell carcinoma diagnosis (SIR=6.65, 95% CI 2.10-15.63), and Merkel cell carcinoma risk was increased following a skin cancer diagnosis (SIR=8.40, 95% CI 4.17-15.08). There were no significant increased risks of second cancers associated with dermatofibrosarcoma. Conclusions: The reciprocated risks between mixed skin carcinomas and upperaerodigestive tract cancers suggest that cigarette smoking or alcohol may play a role in the etiology of mixed skin carcinoma. One explanation for the association between Kaposi’s sarcoma and non-Hodgkin’s lymphoma may be a shared host immune susceptibility to these cancers. The reciprocated risks for various skin tumors is probably largely due to increased surveillance and screening, which may also explain the association between mixed skin tumors and prostate cancer.
Sixth AACR International Conference on Frontiers in Cancer Prevention Research-- Dec 5-8, 2007; Philadelphia, PA