Nonmelanoma Skin Cancer and Second Malignancies: What Is the Risk?

A meta-analysis identified increased risk for some cancers in patients with NMSC.

Are patients who have received a diagnosis of nonmelanoma skin cancer (NMSC) more likely to develop other types of cancer? Investigators attempting to address this issue analyzed 21 prospective studies published in English that measured the relative risk for developing a subsequent primary cancer in patients with NMSC; 18 of the studies were based on registry data, and 3 were cohort studies.

The registry studies showed that patients with a personal history of NMSC were significantly more likely than the general population to develop another type of malignancy (relative risk, 1.12; 95% confidence interval, 1.07–1.17). In the cohort studies, the RR for patients with NMSC was even higher (RR, 1.49; 95% CI, 1.12–1.98). The predisposition to a second malignancy was strongest in those living furthest from the equator; it was not associated with smoking status, and it did not differ by sex. The strongest associations with NMSC were with cancers of the salivary glands, melanoma, lip, mouth, and pharynx and for non-Hodgkin lymphoma. Associations with cancers of the breast, prostate, colorectum, bladder, and esophagus were weaker. No association was observed with carcinomas of the cervix and pancreas.

Comment

Some experts have contended that although sun exposure may cause skin cancer, it also raises vitamin D levels, which prevents other serious malignancies. The results of this extensive analysis refute that idea. For some tumors, such as melanoma and cancer of the lip, the association with nonmelanoma skin cancer most likely derives from a joint cause in ultraviolet radiation. However, for other malignancies such as of the salivary gland, the explanation is less obvious. It is interesting to speculate that as-yet-unidentified genetic factors or immunosuppressive effects of ultraviolet radiation predispose NMSC patients to develop these other neoplasms. Physicians caring for patients with NMSC should watch for signs and symptoms of cancer in other organ systems.

Reviewing Author

Craig A. Elmets, MD

Disclosures

Consultant / Advisory board Astellas Pharmaceuticals

EquityVaxin

Grant / Research support NIH; NIH/NCI; Veteran’s Administration; Ferndale Laboratories; Kyowa Hakko Kirin Pharma, Inc.

Editorial boards Cancer Prevention Research; Photodermatology, Photoimmunology, & Photomedicine; UpToDate; eMedicine; Journal of Dermatological Sciences; JAMA Dermatology

Leadership positions in professional societies American Academy of Dermatology (Vice Chair, Committee on Science and Research); Photomedicine Society (Board of Directors)