Every year, skin cancer becomes the most diagnosed type of cancer in the world. According to the World Health Organization (WHO), between 2 and 3 million cases of non-melanoma skin cancer and more than 132,000 malignant melanomas occur globally each year.

Despite being one of the tumors with the greatest possibility of early detection - as it manifests directly on the surface of the body - it continues to be undervalued, misunderstood and, in many cases, detected late. The confusion between its different types, the normalization of certain changes in the skin and the myths about who can suffer from it contribute to a late diagnosis that can cost life.

Understanding that not all skin cancers are the same is literally a matter of survival.

Not everyone is the same

When most people hear the word “skin cancer,” they imagine a single disease. The reality is considerably more complex. The term groups a group of malignant tumors that originate in different skin cells, with radically different behaviors, rates of progression, treatments and prognoses. Confusing them is not just a medical error: it can be fatal.

Specialists classify skin cancer into three main groups: basal cell carcinoma, squamous cell carcinoma, and melanoma. The first two are collectively known as “non-melanoma skin cancers” and account for the vast majority of cases. Melanoma, although less common, is the most dangerous.

Basal cell carcinoma is the most common of all. It originates in the basal cells, located in the deepest layer of the epidermis. It grows slowly, rarely metastasizes and, when detected early, has a cure rate close to 95%. It usually presents as a pearly or pink bump, a non-healing ulcer, or a flat, scar-like lesion. Although it rarely kills, it can cause significant damage if allowed to advance, destroying nearby tissues and structures such as cartilage or bone.

Squamous cell carcinoma is the second most common. It is born in the squamous cells of the epidermis and has a somewhat more aggressive behavior: it can grow into deep tissues and, in some cases, spread to lymph nodes or distant organs. It frequently presents as a non-healing sore, a scaly scab, or a firm nodule. It is closely linked to cumulative sun exposure over years, and is most prevalent in light-skinned people who have had chronic sun exposure.

Melanoma is the most feared protagonist. Although it represents only 1% of skin cancers, it is responsible for the vast majority of deaths related to this disease. It originates in melanocytes, the cells that produce melanin - the pigment that gives color to the skin. Its ability to spread rapidly to the lymphatic system and other organs makes it a medical emergency when not detected early. The ABCDE rule is the most widespread tool for early identification: Asymmetry, Irregular edge, Varied color, Diameter greater than 6 mm and Evolution or recent change. "It usually derives from melanocytes, which are the cells that form moles. These melanocytes become malignant and become tumorous," Dr. Alberto Conde, a specialist in the Dermatology Service at the San Carlos Clinical Hospital in Madrid, told EFE Health.

Why are some more dangerous?

The difference in the behavior of these tumors lies in their cellular origin and their ability to invade. Melanocytes, being highly mobile cells—their natural function is to migrate and distribute during development—have an easier time invading other tissues. Carcinomas, on the other hand, tend to be more “anchored” locally, especially in their initial stages.

Added to this is the speed of cell replication and the response of the immune system. Some lesser-known skin cancers, such as Merkel cell carcinoma—a rare but extremely aggressive neuroendocrine tumor—or dermatofibrosarcoma protuberans, also deserve attention, although their incidence is lower.

Risk factors

While exposure to ultraviolet radiation—both from the sun and from tanning beds—is the best-known risk factor, it is not the only one. Family history, skin type, weakened immune system, exposure to certain chemicals, human papillomavirus (HPV) infections, and a history of childhood sunburn also significantly increase the risk.

A common mistake is to think that skin cancer “only occurs in light-skinned people.” Dark-skinned people can also develop it; In fact, when they do, it is usually diagnosed in more advanced stages because there is less clinical suspicion and less surveillance. Acral lentiginous melanoma, which appears on the palms, soles of the feet and under the nails, is the most common type in dark-skinned and Asian people, and was the type that affected the musician Bob Marley.

Early detection

Five-year survival for melanoma detected in a localized stage exceeds 98%. When it has already spread to distant organs, that figure drops to less than 30%. The numbers speak for themselves: early detection does not improve the prognosis, it radically transforms it.

Dermatologists recommend monthly self-examination of the skin—checking the entire body with the help of mirrors—and an annual consultation with a specialist for those with risk factors. Dermatoscopy, a technique that allows the deep layers of the skin to be examined with a special illuminated magnifying glass, has revolutionized the ability for early diagnosis.

Treatment: a tailored response

Like its behavior, skin cancer treatment varies depending on the type, stage and location. Low-risk basal cell carcinomas can be treated with simple surgery, cryotherapy, or, in selected cases, topical creams. Squamous cell carcinomas may require more extensive surgery or radiation therapy. Melanoma, depending on its stage, may require surgery, immunotherapy, targeted therapy with molecular inhibitors, radiation therapy, or combinations of these.

Advances in immunotherapy over the past fifteen years have transformed the landscape of advanced melanoma. Medications such as immune checkpoint inhibitors have achieved durable responses in patients who previously had very few options.

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