Skin cancer

A practical, evidence-based guide to understanding skin cancer, recognizing warning signs, and taking effective prevention measures.

Summary in 60 seconds

• Skin cancer includes several tumors: these include basal cell carcinoma, squamous cell carcinoma, and melanoma.
• Ultraviolet radiation (sun and tanning beds) is a major and preventable risk factor. WHO 2022
• Early detection changes the prognosis: a new injury or an injury that changes deserves attention.
• In melanoma, the ABCDE rule (asymmetry, border, color, diameter, evolution) can be helpful, but it does not replace a specialist medical evaluation. American Cancer Society 2025
• In skin carcinomas, recurrent scabs, easy bleeding, or a “wound” that does not heal are common.
• Effective prevention combines shade, protective clothing, and well-applied sunscreen.
• Not every unusual mole is cancer, but it’s also not advisable to monitor a suspicious lesion indefinitely without consulting a specialist.
• The dermatologist can examine the skin, use dermatoscopy, and, if necessary, order a biopsy.
• If there is progressive growth, ulceration, or bleeding, it is prudent to consult a specialist promptly.

The most important warning sign is a new or changing lesion; any persistent change warrants review. American Cancer Society 2025

What is it?

“Skin cancer” is a general term for malignant tumors that originate in the skin. The most common are:

• Basal cell carcinoma (BCC)
• Squamous cell carcinoma (SCC or cutaneous epidermoid)
• Melanoma

Although melanoma is less common, it is closely monitored because of its potential to spread if detected late. National Cancer Institute 2025

Why does skin cancer appear? (common causes)

There is no single cause, but there are factors that increase the risk. In practice, the most relevant and modifiable is exposure to ultraviolet (UV) radiation (sun, tanning beds, sunlamps), which is associated with melanoma and skin carcinomas. WHO 2022

Other influencing factors include personal or family history, skin that burns easily, multiple moles, age, and immunosuppression.

What does it look like and what symptoms does it cause?

It can present itself in different ways. The important thing is to detect what is new, what changes, and what doesn’t heal .

General signs that should raise awareness

• New lesion that persists and/or grows.
• Injury that changes (size, shape, color, relief).
• A lesion that bleeds easily or repeatedly crusts over.
• “Wound” that does not heal .

These signs can appear in both melanoma and skin carcinomas. American Cancer Society 2024

In melanoma: ABCDE rule (guideline)

• A symmetry
• Irregular borders
• Uneven color
• Diameter (sometimes >6 mm, but can be smaller)
• E evolution (change)

The “E” in evolution is especially useful: sustained change often carries more weight than a single snapshot. Abbasi 2004

What can you do today? (safe and concrete measures)

1. Check your skin regularly (including back, scalp, nails and soles).

2. If there is an injury that worries you, document changes with comparable photos (same light/distance), without replacing a consultation.

3. Use full sun protection :

   • Choose a product with broad spectrum , SPF ≥30 and use it in sufficient quantity;

   • Reapply every 2 hours outdoors and after swimming or sweating. American Academy of Dermatology 2025

4. Prioritize physical measures : shade, tightly woven clothing, hat, UV-protective sunglasses.

5. Avoid tanning beds .

What NOT to do? (common mistakes)

• Don’t «wait months» to see if a clearly changing injury resolves itself.
• Do not attempt to diagnose or rule out cancer using only the internet or photos.
• Do not scrape, cut, cauterize, or «burn» injuries at home.
• Do not use home remedies as a substitute for a medical evaluation.
• Don’t assume that if it doesn’t hurt, it doesn’t matter.

When should I consult?

Consult us with priority if you notice:

• A new injury that grows in weeks or a few months.
• A mole/spot that changes in size, shape, color, or texture.
• Spontaneous bleeding or with minimal friction.
• Ulcer/wound that does not heal or heals and comes back.
• Recurrent scab in the same spot.
• A lesion “ different from the rest ” of your moles.
• New pigmentation under a nail or on mucous membranes .

These signs are common reasons for a dermatological evaluation. American Cancer Society 2025

What does a dermatologist usually do?

During a consultation, the dermatologist usually:

1. Targeted medical history (duration of evolution, changes, bleeding, pain, sun exposure, history).

2. Complete skin examination as needed.

3. Dermatoscopy : an instrument that allows visualization of structures not visible to the naked eye and helps in deciding treatment. American Cancer Society 2023

4. Biopsy, if the lesion warrants it: this is the method used to confirm the diagnosis under a microscope. National Cancer Institute 2025

Frequently Asked Questions

Is every large mole cancerous?

• No. Many moles are benign. What is most indicative is the change (evolution) and the clinical context.

Does skin cancer always hurt?

• No. Many don’t hurt at first; they may appear as scabs, bleeding, or slow growth.

If I use sunscreen, am I fully protected?

• No. Sunscreen is a key part, but it works best in conjunction with clothing, a hat, shade, and responsible sun exposure habits. CDC 2024

Is melanoma always black?

• No. It can have several colors or even be lightly pigmented.

Can a wound that doesn’t heal be skin cancer?

• It may be, and it deserves evaluation, especially if it persists or recurs. American Cancer Society 2024

Can young people get skin cancer?

• Yes. Although some types increase with age, melanoma can occur in young people.

Does a biopsy «spread» cancer?

• Generally, no. Biopsy is the gold standard for confirming a diagnosis when there is clinical suspicion. American Cancer Society 2023

Bibliography and sources

• World Health Organization. Ultraviolet radiation [Internet] . Geneva: World Health Organization; 2022 Jun 21 [cited 2026 May 10] . Available from: https://www.who.int/news-room/fact-sheets/detail/ultraviolet-radiation
• Centers for Disease Control and Prevention. Sun Safety Facts [Internet] . Atlanta: CDC; 2026 Feb 10 [cited 2026 May 10] . Available from: https://www.cdc.gov/skin-cancer/sun-safety/index.html
• American Academy of Dermatology Association. How to apply sunscreen [Internet] . Rosemont (IL): American Academy of Dermatology Association; 2025 Aug 15 [cited 2026 May 10] . Available from: https://www.aad.org/public/everyday-care/sun-protection/shade-clothing-sunscreen/how-to-apply-sunscreen
• American Cancer Society. Signs and Symptoms of Melanoma Skin Cancer [Internet] . Atlanta: American Cancer Society; 2025 Feb 25 [cited 2026 May 10] . Available from: https://www.cancer.org/cancer/types/melanoma-skin-cancer/detection-diagnosis-staging/signs-and-symptoms.html
• American Cancer Society. Basal and Squamous Cell Skin Cancer Symptoms [Internet] . Atlanta: American Cancer Society; 2024 Oct 31 [cited 2026 May 10] . Available from: https://www.cancer.org/cancer/types/basal-and-squamous-cell-skin-cancer/detection-diagnosis-staging/signs-and-symptoms.html
• American Cancer Society. Tests for Melanoma Skin Cancer [Internet] . Atlanta: American Cancer Society; 2023 Oct 27 [cited 2026 May 10] . Available from: https://www.cancer.org/cancer/types/melanoma-skin-cancer/detection-diagnosis-staging/how-diagnosed.html
• PDQ Adult Treatment Editorial Board. Melanoma Treatment (PDQ®)–Patient Version [Internet] . Bethesda (MD): National Cancer Institute; 2025 May 16 [cited 2026 May 10] . Available from: h ttps://www.cancer.gov/types/skin/patient/melanoma-treatment-pdq
• PDQ Screening and Prevention Editorial Board. Skin Cancer Prevention (PDQ®)–Health Professional Version [Internet] . Bethesda (MD): National Cancer Institute; 2025 Apr 8 [cited 2026 May 10] . Available from: https://www.cancer.gov/types/skin/hp/skin-prevention-pdq
• Abbasi NR, Shaw HM, Rigel DS, Friedman RJ, McCarthy WH, Osman I, et al. Early diagnosis of cutaneous melanoma: revisiting the ABCD criteria. JAMA. 2004;292(22):2771-6. doi:10.1001/jama.292.22.2771.
• Tsao H, Olazagasti JM, Cordoro KM, Brewer JD, Taylor SC, Bordeaux JS, et al. Early detection of melanoma: reviewing the ABCDEs. J Am Acad Dermatol. 2015;72(4):717-23. doi:10.1016/j.jaad.2015.01.025.
• Duarte AF, Sousa-Pinto B, Azevedo LF, Barros AM, Puig S, Malvehy J, et al. Clinical ABCDE rule for early melanoma detection. Eur J Dermatol. 2021;31(6):771-8. doi:10.1684/ejd.2021.4171.
• Green A, Williams G, Neale R, Hart V, Leslie D, Parsons P, et al. Daily sunscreen application and betacarotene supplementation in prevention of basal-cell and squamous-cell carcinomas of the skin: a randomized controlled trial. Lancet. 1999;354(9180):723-9.
• Green AC, Williams GM, Logan V, Strutton GM. Reduced melanoma after regular sunscreen use: randomized trial follow-up. J Clin Oncol. 2011;29(3):257-63. doi:10.1200/JCO.2010.28.7078.
• Dinnes J, Deeks JJ, Grainge MJ, Chuchu N, Ferrante di Ruffano L, Matin RN, et al. Visual inspection for diagnosing cutaneous melanoma in adults. Cochrane Database Syst Rev. 2018;12(12):CD013194. doi:10.1002/14651858.CD013194.