Skin cancer is the most common form of cancer in humans. The incidence of skin cancer has been increasing over recent decades, at least in part related to increased sun and tanning booth exposure. Skin cancers are most often categorized as melanoma, the most aggressive type, or non-melanoma skin cancer (NMSC), with the latter being the most common. Prognosis for melanoma and management guidelines differ significantly from those for NMSC.
More than 5.4 million cases of NMSC occur in the United States annually, affecting more than 3.3 million Americans, with many individuals having more than one type. The most common of these cancers is the basal cell carcinoma (BCC [image, top]), accounting for about 80% of NMSC. Squamous cell carcinoma (SCC [image, bottom]) accounts for 20% of the NMSC. While estimates are difficult to make since NMSC are not typically followed by registries, about 2000 people in the US die annually from NMSC. NMSC more commonly causes local tissue destruction and disfigurement. Even more common than BCCs are actinic keratosis (AKs), which are considered pre-cancers of the SCC type.
Melanoma is generally a more dangerous skin cancer that develops from the pigment cells of the skin. More than 76,000 cases of invasive melanoma are diagnosed in the US annually and the cancer is responsible for more than 10,000 deaths every year—a mortality rate 5 times higher than for NMSC. Melanoma and NMSC present in clinically distinct manners which we will describe in the segments of the Special Report to follow.
Prevention of skin cancer is of primary importance and primary care physicians have a critical role to play in educating patients on how to minimize exposure. Ultraviolet energy has been identified as the major risk factor in skin cancer development. Sun avoidance and protection can prevent the DNA damage that results in cancer development, sometimes not until decades after exposure. “Sun avoidance” does not mean staying indoors. Outdoor activities can be safely performed and enjoyed with use of effective protection to avoid tan and burn of the skin. Good skin protection can be achieved with sun-protective clothing made with UPF (UV protection factor) 50+ rated fabrics or by wearing dark-colored fabrics that do not allow light to penetrate. Wearing a hat for head and neck protection, glasses for eye protection is also recommended and finally use of a good sunscreen is advisable. Suncreens can be organic/chemical or physical blockers. In general higher SFP (sun protection factor) sunscreens block out more light. Also, physical sunblocks containing micronized zinc or titanium are more stable, inert, and less irritating to the skin than organic/chemical blockers. They will not disintegrate in heat as chemical blockers do.
Early diagnosis of skin cancer is key in preventing complications from cancer growth or spread. The diagnosis of skin cancer can be challenging to clinicians faced with time constraints in examining and treating patients. This Special Report focuses on clinical diagnosis and basic management of common NMSC types that may be encountered in the primary care setting. Installments to follow will cover:
► Basal cell carcinoma
► Pigmented basal cell carcinoma
► Squamous cell carcinoma, actinic keratosis
First up: a multiple-choice pretest on dermatologic neoplasms aimed at primary care physicians. The questions will be answered in upcoming segments of this Special Report and you will see them again, as a post-test, at the conclusion of the series.