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Skin cancer of the head and neck is a heterogeneous group of malignancies that together constitute the most common cancer of this anatomic region. The majority of cases are nonmelanoma skin cancers (NMSC) such as basal cell carcinoma (BCC) and squamous cell carcinoma (SCC), but melanoma and Merkel cell carcinoma (MCC) are increasingly encountered. Although most skin cancers of the head and neck are successfully treated by a variety of practitioners using an array of modalities, melanoma and aggressive variants of NMSC demand a multidisciplinary approach—the challenge lies in recognizing the dangerous lesions early in their course to facilitate comprehensive staging and treatment. Because melanoma is thoroughly addressed elsewhere in this text, this chapter will focus on NMSC, particularly BCC and SCC, in addition to the unique aspects of cutaneous melanoma of the head and neck.
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About 3.5 million NMSC are diagnosed yearly in the United States, with BCC constituting roughly 80% of these cases.1 SCC accounts for about 20% of diagnoses, while MCC, rare adnexal carcinomas, and sarcomas comprise about 1% as well.2 The true incidence is hard to ascertain, as NMSC is infrequently reported to cancer registries, including the Survival Epidemiology and End Results (SEER) database. Health care expenditures related to NMSC exceeded $426 million per year by the mid-2000s in the US Medicare population alone—it may even reach $2 billion; costs are likely even greater in countries where these patients are more often treated in the hospital setting.3,4 Though less common than NMSC, cutaneous melanoma has been estimated to afflict over 76,000 people in 2013 and it accounts for over 70% of all deaths from skin cancer.5,6 The lethality of melanoma is widely recognized, but the mortality risk for aggressive NMSC, particularly SCC, is more difficult to quantify. Between 3900 and 8791 deaths are estimated to be annually attributable to cutaneous SCC (cSCC), with cSCC contributing to as many deaths as melanoma in the central and southern United States.7
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Skin cancer is typically related to exposure to ultraviolet (UV) radiation, and 75% of NMSC arise on the head and neck because of the increased sun exposure of these areas.1 Interestingly, head and neck subsites only account for 15% to 21% of cutaneous melanoma; evidence suggests a worse prognosis for head and neck sites, particularly the scalp and neck.8,9 Both NMSC and melanoma are increasing in frequency, and the at-risk populations share some demographic features. Although Caucasian men over age 50 are at greater risk of developing NMSC, there is evidence that the disease is becoming more common among younger patients of both genders and women, and that aggressive variants manifest in these subpopulations as well.10,11 Similarly, cutaneous melanoma most commonly afflicts Caucasian men aged 55 to 64, but head and neck melanomas tend to occur more commonly in patients over ...