Skin Cancer

All the information about the different types of skin cancer: causes, symptoms, and treatments.

Symptoms and Causes

Skin cancer is one of the most common cancers worldwide. According to the Spanish Association Against Cancer (AECC), it accounts for approximately 7% of all cancers diagnosed each year in Spain.

There are different types of skin cancer, classified into two main groups:

Carcinomas: These affect the epithelial cells that cover organs, including the skin.

Squamous cell carcinomas: Occur in the thin, flat cells that make up the upper layer of the epidermis, the most superficial part of the skin.
Basal cell carcinomas: The most common type; they begin in the basal cells, located just beneath the squamous cells, in the lower part of the epidermis.

Melanomas: Less common but more aggressive, as they have a greater ability to spread to surrounding tissues. They originate in melanocytes, the cells responsible for synthesizing melanin.

Although skin cancer is a serious disease, it generally has a good prognosis (even melanoma) and rarely causes death. Early detection is essential, so regular check-ups are recommended.

Symptoms

Symptoms of skin cancer vary depending on the type. The most common are:

Squamous cell carcinoma: Signs typically appear on the face, neck, ears, hands, and arms.

Red, rough patches that may bleed and form scabs.
Firm, raised red nodules.
Reddish sores or ulcers in the mouth.
Red patches in the anus or genital area.

Basal cell carcinoma: Most frequently occurs on the head and face.

Translucent, shiny bumps.
Slightly raised brown, black, or blue lesions with dark specks and translucent borders.
Flat, scaly patches.
Whitish, scar-like lesions.
Irregular blood vessels.

Melanoma: Usually develops on the face, arms, legs, or back.

Changes in the shape, size, or color of existing moles.
Pigmented, irregularly shaped lumps.

Although cancerous lesions often appear on skin areas most exposed to the sun, they can also occur in other regions such as the mouth, soles of the feet, nails, or palms—especially in the case of melanoma.

Causes

The most common cause of skin cancer is prolonged exposure to ultraviolet (UV) rays from sunlight or tanning lamps. Excessive ultraviolet light emits radiation that causes DNA changes in skin cells, which over time can develop into cancerous cells.

However, skin cancer can also occur in areas not exposed to the sun for reasons that remain unclear.

Risk Factors

The main factors that increase the risk of developing skin cancer include:

Exposure to ultraviolet light from the sun or tanning beds.
Skin that burns easily, regardless of color (phototypes I, II, and to a lesser extent, III).
Fair or red hair, freckles, and blue eyes (phototypes I and II).
Having numerous moles.
History of sunburns, particularly those that caused blistering.
Childhood sunburns.
Weakened immune system.
Personal or family history of skin cancer.

Complications

The most significant complications of skin cancer include:

Metastasis: Cancer cells spread to other organs or lymph nodes, increasing the risk of death. This is typical of melanoma, as carcinomas rarely metastasize.
Recurrence: The cancer returns after having disappeared.
Destruction of healthy tissues surrounding the tumor.

Prevention

The best way to prevent skin cancer is by following these recommendations:

Avoid prolonged sun exposure.
Do not sunbathe during peak hours.
Refrain from using tanning booths.
Apply high-SPF sunscreen all year round.
Stay in the shade whenever possible.
Wear sunglasses and a hat.
For particularly sensitive skin, wear protective clothing.
Observe any changes in moles and warts.
Examine the skin regularly for new lesions.

Which specialist treats skin cancer?

The diagnosis of skin cancer is usually made in medical-surgical dermatology and venereology, while treatment typically involves specialists in medical oncology and radiation oncology.

Diagnosis

Self-examination plays a key role in the early diagnosis of skin cancer, as patients are familiar with their existing moles and warts and can detect changes or new lesions.

During the consultation, lesions are examined for abnormalities. These evaluations should include the face, scalp, neck, chest, shoulders, armpits, arms, hands, back, buttocks, and legs.

Attention should be paid to:

Changes in the shape, color, or size of lesions.
Appearance of new spots.
To detect melanoma, the A, B, C, D, E rule is followed:

A – Asymmetry: The lesion is not symmetrical.
B – Border: Undefined or irregular edges.
C – Color: The mole is not uniform in color; it may show reddish, bluish, or brownish areas.
D – Diameter: Spots larger than six millimeters are considered suspicious.
E – Evolution: They change over time and may cause pain or bleeding.

To confirm the diagnosis, a biopsy is usually performed. A tissue sample is taken and examined in the laboratory for cancerous cells.

In addition to the above parameters, lesions are classified based on size and depth to stage the cancer:

Stage 0 (carcinoma in situ): Abnormal cells are present in the squamous or basal cells of the epidermis.
Stage I: Cancerous tumors measure up to two centimeters and are confined to the epidermis.
Stage II: Lesions measure between two and four centimeters and extend into the upper layer of the dermis.
Stage III: Malignant cells may present the following characteristics:

Tumor larger than four centimeters that invades the subcutaneous tissue or reaches the bone superficially, or a lymph node smaller than three centimeters.
Tumor smaller than four centimeters with cancerous cells spread to a lymph node smaller than three centimeters.

Stage IV: Lesions of any size that reach the deepest layer of the skin (reticular dermis) and spread to the bone, nerves, subcutaneous tissue, or lymph nodes. Metastasis to other organs may occur.

Tumor spread is determined through imaging tests or a sentinel lymph node biopsy, which identifies the first lymph node to which cancer cells spread before affecting other organs.

Treatment

Skin cancer treatments vary depending on the type, stage, and individual characteristics of each patient. In many cases, different therapies are combined to achieve better outcomes.

The most common approaches include:

Surgery: Various surgical techniques can be used:

Excision: Removal of cancerous cells along with some surrounding healthy tissue.
Mohs surgery: Thin layers of the tumor are removed and examined under a microscope after each step. The procedure ends once no cancer cells are detected, minimizing the removal of healthy tissue.
Laser surgery: Superficial abnormal tissues are removed using a laser.
Electrosurgery: The tumor is removed with a curette (a spoon-shaped instrument), and any remaining cancerous cells are destroyed with an electrode that also stops bleeding.
Cryosurgery: Intense cold (liquid nitrogen or argon gas) is used to freeze abnormal tissue.
Dermabrasion: Superficial skin layers containing precancerous or cancerous cells are removed with a rotating disk that scrapes the tissue.

Radiotherapy: High-energy ionizing radiation is used to destroy cancerous tissues.
Chemotherapy: Drugs are administered to slow or stop the formation of cancer cells.
Immunotherapy: The patient’s immune system is stimulated to help eliminate cancer cells.
Photodynamic therapy: Ultraviolet light is used to slow the growth of cancer cells.