Exposure to environmental trace elements has been studied in relation to many cancers. However, an association between exposure to trace elements and skin cancer remains less understood. Therefore, we conducted a systematic review of published epidemiologic literature examining the association between exposure to trace elements, and risk of melanoma and keratinocyte carcinoma in humans. We identified epidemiologic studies investigating exposure to arsenic, cadmium, chromium, copper, iron, selenium, and zinc and risk of skin cancer in humans. Among the minerals, arsenic, selenium, and zinc had more than 5 studies available. Exposure to arsenic was associated with increased risk of keratinocyte carcinoma, while too few studies existed on melanoma to draw conclusions. Exposure to selenium was associated with possible increased risk of keratinocyte carcinoma. Studies of zinc and skin cancer were case-control in design and were found to have inconsistent associations. The data on the association between cadmium, chromium, copper, and iron and risk of skin cancer remain too sparse to draw any conclusions. In summary, epidemiologic studies on exposure to trace elements and cutaneous malignancies are limited. Studies with larger sample sizes and prospective designs are warranted to improve our knowledge of trace elements and skin cancer.

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An increased risk for subsequent primary cancers has been observed in patients with skin cancer including squamous cell carcinoma (SCC). Although the mechanism of such association has not been fully understood, several factors including immunosuppression may play a role. However, of greater focus is the risk of subsequent hematologic malignancies in patients with lip SCC which has not been previously reported. The aim of this study was to explore the risk of hematologic malignancy in lip SCC survivors. The SEER database (2000-2014) was searched to detect all patients with a primary cutaneous lip SCC who survived 2 months after diagnosis. SCC was detected by histology codes for squamous neoplasms (8050-8089) in conjunction with primary site for lip (C00.0-C00.02; C00.06; C00.08; C00.09). Site recode B ICD-O-3 was used to detect hematologic malignancy. Standardized Incidence Ratios (SIRs), ratio of the observed (O) in lip SCC survivors, to the expected (E) in the general population (O:E ratios), and 95% confidence intervals (CIs), were calculated. Of 5,537 individuals with lip SCC, 65 developed 1 primary lymphatic or hematopoietic malignancies, and particularly showing a significantly increased risk for lymphoma (O:E 1.46, 95% CI 1.04-1.99). The mean time in months to the development of a hematologic malignancy was 46 (range: 2-164 months). Interestingly, when stratified by gender, risk of subsequent lymphoma remained significant for males (O:E 1.63, 95% CI 1.14-2.25), but not for females (O:E 0.75, 95% CI 0.21-1.93). These findings that nationwide, cutaneous lip SCC survivors are at increased risk for developing primary lymphatic malignancies, especially lymphoma, warrant enhanced surveillance for lip SCC patients. In addition, exploration to determine the risk of subsequent primary malignancy in non-lip cutaneous SCC seems warranted.