What comes to mind when you hear the words "skin cancer"? Chances are, "melanoma" is one of them. Despite being a familiar term, melanoma only accounts for about 1% of all skin cancers, though it contributes significantly to skin cancer deaths. Here, we'll break down the differences between the most common types of skin cancer and melanoma.
Before diving into the different types of skin cancers, a brief anatomy lesson is helpful to fully understand what skin cancer is. There are multiple layers of skin: the epidermis, dermis, and hypodermis. The prefix "epi-" means "outer" or "on top of" (as in the epidermis), and "hypo-" means "under" (as in the hypodermis).
Source: Skin Layers Anatomy Diagram
A normal skin cell is generated in the deepest part of the epidermis, known as the basal layer, and migrates to the surface, where it eventually flakes off. Within the epidermis, there are multiple types of skin cells. The two we will focus on are melanocytes and keratinocytes. Melanocytes produce pigment in the skin, known as melanin, while keratinocytes form the skin's barrier, preventing the entry of foreign bodies like bacteria, chemicals, and other harmful agents. As all cells have DNA, skin cells are no exception, and damaged DNA is the basis of what can lead to skin cancer.
Source: NCBI Overview of Skin Anatomy
Outlined below are the most common types of skin cancer and what causes their development.
Basal Cell Carcinoma (BCC)
About 80% of diagnosed skin cancers are basal cell carcinomas, making them the most common type of skin cancer. While 80% is a concerning statistic, basal cell carcinomas rarely metastasize and tend to grow slowly. However, it’s important to treat them, as they can eventually penetrate deeper into the skin and destroy surrounding tissue, potentially becoming fatal. BCC occurs when the DNA of a keratinocyte in the basal layer of the epidermis is damaged, leading to abnormal growth and the formation of a tumor on the skin's surface.
Squamous Cell Carcinoma (SCC)
Like basal cell carcinoma, squamous cell carcinoma can form due to DNA damage in keratinocytes from factors like UV exposure. The difference lies in the location of the cancer's development. SCC originates in the epidermis, closer to the skin’s surface than BCC. While SCC is less common, it requires more urgent treatment due to its higher likelihood of spreading to nearby organs.
Melanoma
Although melanoma is the most well-known term, it accounts for a small fraction of cancer diagnoses. Melanoma occurs when the DNA of melanocytes, found in the basal layer of the epidermis, is damaged. Despite its rarity, melanoma is responsible for the majority of skin cancer deaths due to its ability to spread quickly to other organs and develop anywhere on the body—even behind the eyes. Early detection and treatment are crucial for improving outcomes.
Who Is at Risk for Skin Cancer?
Skin cancer can occur in anyone, but several factors increase the risk, including:
Naturally fair skin
Skin that burns, freckles easily, or becomes red and irritated in the sun
Naturally light-colored eyes or hair
A history of tanning or sunburns
A large number of moles
Older age
Diagnosis
Diagnosing skin cancers typically involves taking a biopsy of the suspicious area and sending it to a pathologist, who will determine whether the sample is cancerous and, if so, what type. Further testing may be needed to stage the cancer, typically ranging from stages I to IV, with IV being the most severe.
Treatment
Treatment for skin cancer varies depending on the type. Some precancerous or early-stage cancerous lesions can be frozen off with liquid nitrogen. Other common treatment methods include excision, Mohs surgery, electrodessication and curettage, radiation, chemotherapy, and photodynamic therapy. For more details, refer to this comprehensive resource:
Overall, it's important to understand that while skin cancer can affect anyone, there are ways to reduce the risk by limiting exposure to contributing factors. If you're concerned about your risk or suspect you may have skin cancer, consult a dermatologist. Many insurance plans don't cover dermatology visits as medically necessary, which can be a barrier to treatment. The following resource can help you find free skin cancer screenings and guide you on how to perform a self-exam:
Sources:
Mayo Clinic - Skin Cancer Diagnosis & Treatment Assessed and Endorsed by the Medreport Medical Review Board