What is Skin Cancer? Skin cancer is the most common type of cancer in the United States, with over 5 million cases diagnosed each year. It begins in the skin cells and is primarily caused by ultraviolet (UV) radiation from the sun or tanning beds. The three main types are basal cell carcinoma (most common, least dangerous), squamous cell carcinoma (common, usually curable), and melanoma (less common but most dangerous). Early detection dramatically improves outcomes for all types.
Annual Cases (US)
5+ Million
Most Common Type
Basal Cell (80%)
Melanoma 5-Year Survival
99% (Localized)
Preventability
90% Preventable
Types of Skin Cancer
Basal Cell Carcinoma (BCC)
80% of all skin cancers
- Begins in basal cells at the bottom of the epidermis
- Grows slowly and rarely spreads (metastasizes)
- Most common on sun-exposed areas: face, head, neck
- Appears as pearly or waxy bump, or flat, flesh-colored/brown scar-like lesion
- Highly curable when detected early (99%+ cure rate)
- Can be locally destructive if left untreated
Squamous Cell Carcinoma (SCC)
15-20% of skin cancers
- Arises from squamous cells in the outer layer of skin
- More aggressive than BCC, can metastasize (2-5% of cases)
- Common on sun-exposed areas: face, ears, hands, forearms
- Appears as firm red nodule or flat lesion with scaly, crusted surface
- Often develops from actinic keratoses (precancerous lesions)
- Higher metastasis risk in immunosuppressed patients (organ transplant recipients)
Melanoma
Only 1% of skin cancers but causes majority of skin cancer deaths
- Develops in melanocytes (pigment-producing cells)
- Can develop in existing mole or appear as new dark spot
- Spreads rapidly if not caught early
- Can occur anywhere on body, even areas without sun exposure
- Most deadly form but highly curable when detected early
- Incidence increasing, especially in young adults
Less Common Types
- Merkel cell carcinoma: Rare, aggressive cancer of neuroendocrine cells. Often appears on head/neck in elderly patients
- Kaposi sarcoma: Linked to HIV/AIDS and immunosuppression. Purple/red patches or nodules
- Sebaceous gland carcinoma: Rare, often around eyelids. Can be aggressive
- Dermatofibrosarcoma protuberans: Rare, slow-growing but locally aggressive
Risk Factors
Major Risk Factors
- UV radiation exposure: #1 risk factor
- Cumulative sun exposure over lifetime
- History of severe sunburns, especially in childhood
- Indoor tanning bed use (increases melanoma risk by 75% if started before age 35)
- Fair skin: Less melanin = less natural protection
- Skin that burns easily, freckles, doesn't tan
- Light hair (blonde, red)
- Light-colored eyes (blue, green)
- Many moles: More than 50 common moles or any atypical (dysplastic) moles
- Family history: 10% of melanomas are familial
- CDKN2A, CDK4 gene mutations
- Familial atypical multiple mole melanoma (FAMMM) syndrome
- Personal history: Previous skin cancer increases risk of developing another
- Immunosuppression: Organ transplant recipients have 100x higher risk of SCC
- Age: Risk increases with age (50+ for BCC/SCC, but melanoma affects younger adults too)
Other Risk Factors
- Xeroderma pigmentosum (genetic disorder affecting DNA repair)
- Prior radiation therapy
- Exposure to arsenic or certain chemicals
- Chronic skin inflammation or injury
- HPV infection (especially for SCC in genital area)
Good News: Skin cancer is one of the most preventable cancers! Up to 90% could be prevented by protecting skin from UV radiation.
Signs and Symptoms - The ABCDE Rule for Melanoma
A
Asymmetry
One half of the mole doesn't match the other half
B
Border
Edges are irregular, ragged, notched, or blurred
C
Color
Not uniform; different shades of brown, black, pink, red, white, or blue
D
Diameter
Larger than 6mm (pencil eraser), though melanomas can be smaller
E
Evolving
Changing in size, shape, color, or elevation; new symptoms like itching or bleeding
Other Warning Signs
- The "ugly duckling" sign: A mole that looks different from all your other moles
- Sore that doesn't heal: Persists for weeks or months
- Spread of pigment: From border into surrounding skin
- Redness or swelling beyond the border
- Itching, tenderness, or pain
- Oozing, scaling, or bleeding
- Lump or nodule under the skin
Important: Melanoma can occur in areas with little sun exposure, including palms, soles of feet, nail beds, mucous membranes, and even eyes. Always report any new or changing lesion to your doctor.
Diagnosis
Screening and Self-Examination
- Monthly self-skin exams: Check entire body using mirrors, including scalp, between toes, genital area
- Annual skin exam by dermatologist: Especially if high risk
- Dermoscopy: Magnified examination of suspicious lesions
- Total body photography: For patients with many moles to track changes
Diagnostic Tests
- Biopsy (definitive diagnosis):
- Excisional biopsy: Remove entire lesion (preferred for suspected melanoma)
- Punch biopsy: Remove circular core of tissue
- Shave biopsy: Shave off surface layers (NOT recommended for melanoma)
- Pathology examination: Determines cancer type, thickness, other characteristics
- Sentinel lymph node biopsy: For melanoma ≥1 mm thick or other high-risk features
- Imaging: If melanoma suspected to have spread
- CT scan of chest, abdomen, pelvis
- PET/CT scan
- Brain MRI (for stage III/IV melanoma)
- Genetic testing: BRAF, NRAS, c-KIT mutations in melanoma (guides treatment)
Staging - Melanoma
Breslow Thickness (Most Important Factor)
| Thickness | Description | 5-Year Survival |
|---|---|---|
| <1 mm | Thin melanoma | ~98% |
| 1-2 mm | Intermediate | ~90-95% |
| 2-4 mm | Thick | ~78-87% |
| >4 mm | Very thick | ~60-70% |
AJCC Staging (8th Edition)
- Stage 0 (Melanoma in situ): Cancer cells only in epidermis, haven't invaded deeper
- Stage I: Localized, <2 mm thick, no lymph node involvement (99% 5-year survival)
- Stage II: Localized, >1 mm thick or ulcerated, no lymph node involvement (65-94% survival)
- Stage III: Spread to nearby lymph nodes or skin (40-78% survival depending on substage)
- Stage IV: Distant metastases (lungs, liver, brain, bone, distant skin) (15-30% 5-year survival, improving with immunotherapy)
Key Point: When melanoma is detected early (localized, stage 0-I), the 5-year survival rate is 99%. This drops to 27% for stage IV disease with traditional treatments, but immunotherapy has dramatically improved outcomes for advanced melanoma.
Treatment Options
Basal Cell and Squamous Cell Carcinoma Treatment
Surgical Options
- Excisional surgery: Standard treatment, remove tumor with margin of healthy tissue
- Mohs micrographic surgery: Layer-by-layer removal with immediate microscopic examination
- Highest cure rate (99% for primary BCC)
- Preserves maximum healthy tissue
- Preferred for face, ears, hands, genitals
- Best for recurrent tumors or ill-defined borders
- Curettage and electrodesiccation: Scrape tumor, then cauterize base. For small, low-risk tumors
- Cryotherapy: Freeze tumor with liquid nitrogen. For small, superficial lesions
Radiation Therapy
- For patients who can't undergo surgery
- Elderly patients or those with medical contraindications
- Adjuvant treatment for high-risk SCC
- Cure rates comparable to surgery for BCC/SCC
Topical Treatments
- Imiquimod cream (Aldara): Immune response modifier for superficial BCC
- 5-Fluorouracil cream: Topical chemotherapy for superficial BCC/SCC in situ
- Applied for weeks to months
- Can cause skin irritation, redness
Photodynamic Therapy (PDT)
- Photosensitizing agent applied to skin, then activated with light
- For superficial BCC, actinic keratoses
- Good cosmetic results
Advanced BCC/SCC
- Hedgehog pathway inhibitors for BCC:
- Vismodegib (Erivedge)
- Sonidegib (Odomzo)
- For locally advanced or metastatic BCC when surgery not possible
- Response rate 30-50%
- Immunotherapy for advanced SCC:
- Cemiplimab (Libtayo) - PD-1 inhibitor
- Pembrolizumab (Keytruda)
- For metastatic or locally advanced SCC
Melanoma Treatment
Surgery
- Wide local excision: Standard treatment
- Margins based on Breslow thickness
- 0.5-1 cm margin for thin (<1 mm)
- 1-2 cm margin for thicker melanomas
- Sentinel lymph node biopsy (SLNB):
- For melanoma ≥1 mm or <1 mm with high-risk features
- Identifies first lymph node(s) draining from tumor
- If positive, may proceed to complete lymph node dissection (controversial) or surveillance
- Lymph node dissection: Remove regional lymph nodes if involved
- Metastasectomy: Surgery to remove isolated metastases in select cases
Adjuvant Therapy (After Surgery for High-Risk Melanoma)
- Immunotherapy:
- Pembrolizumab (Keytruda) - approved for stage III adjuvant, 1 year
- Nivolumab (Opdivo) - approved for stage III/IV adjuvant, 1 year
- Reduces recurrence risk by ~40-45%
- Targeted therapy (for BRAF V600 mutations):
- Dabrafenib + trametinib - approved for stage III adjuvant, 1 year
- Reduces recurrence risk by ~50%
Treatment for Advanced/Metastatic Melanoma
Revolutionary Progress: Immunotherapy has transformed melanoma from a death sentence to a manageable disease for many patients. 5-year survival for stage IV melanoma has increased from <10% (2010) to 40-50%+ (2025) with modern immunotherapy.
- Immunotherapy (Checkpoint Inhibitors):
- Anti-PD-1 monotherapy: Pembrolizumab or nivolumab
- Response rate: 40-45%
- Median survival: ~2-3 years
- Some patients achieve durable remissions (5-10+ years)
- Combination: Nivolumab + Ipilimumab (anti-CTLA-4):
- Response rate: 58%
- 5-year survival: ~52%
- Higher toxicity (55-60% severe side effects)
- Best long-term outcomes
- Anti-PD-1 monotherapy: Pembrolizumab or nivolumab
- Targeted Therapy (BRAF V600 Mutations - 50% of melanomas):
- BRAF + MEK inhibitors:
- Dabrafenib + trametinib
- Vemurafenib + cobimetinib
- Encorafenib + binimetinib
- Response rate: 60-70%
- Rapid responses (weeks)
- Median PFS: ~12 months
- Often used before or instead of immunotherapy
- BRAF + MEK inhibitors:
- Other targeted therapies:
- c-KIT inhibitors (imatinib) for c-KIT mutations (rare, ~5%)
- NRAS inhibitors (in development)
- Chemotherapy: Dacarbazine, temozolomide - rarely used now, largely replaced by immunotherapy/targeted therapy
- Radiation: For brain metastases (SRS), bone metastases, symptom control
- Tumor-infiltrating lymphocyte (TIL) therapy: Emerging treatment, very promising results
Prevention
90% of skin cancers are preventable through sun protection!
Sun Protection Strategies
- Sunscreen:
- SPF 30+ broad-spectrum (UVA and UVB)
- Apply 30 minutes before sun exposure
- Reapply every 2 hours, or after swimming/sweating
- Use 1 ounce (shot glass full) for entire body
- Don't forget ears, neck, tops of feet, scalp (if balding)
- Protective clothing:
- Long-sleeved shirts, long pants
- UPF-rated clothing (UPF 50+ blocks 98% UV rays)
- Wide-brimmed hat (3+ inch brim)
- UV-blocking sunglasses
- Seek shade: Especially between 10 AM - 4 PM when UV rays strongest
- NEVER use tanning beds: Increases melanoma risk by 75% if used before age 35
- Protect children: One blistering sunburn in childhood doubles melanoma risk
- Check UV Index: Take extra precautions when UV index is high
Early Detection
- Monthly self-skin exams: Know your skin, check for new or changing lesions
- Annual dermatologist exam: Especially if high risk
- Photograph moles: Track changes over time
- Don't ignore suspicious lesions: "When in doubt, check it out"
Chemoprevention (For Very High-Risk Individuals)
- Nicotinamide (vitamin B3): 500 mg twice daily reduces BCC/SCC by 23% in high-risk patients
- Retinoids: For transplant recipients or xeroderma pigmentosum
Survival and Prognosis
Basal Cell Carcinoma
- Cure rate: 95-99% with appropriate treatment
- Recurrence: 5% with standard excision, <1% with Mohs surgery
- Metastasis: Extremely rare (<0.1%)
- Death rate: Very low, ~2,000 deaths per year in US despite millions of cases
Squamous Cell Carcinoma
- Cure rate: 95% for low-risk SCC
- Metastasis: 2-5% overall, higher for high-risk features (ear, lip, thick, poorly differentiated, immunosuppressed patients)
- Deaths: ~15,000 per year in US
Melanoma (Stage-Specific 5-Year Survival)
| Stage | Description | 5-Year Survival |
|---|---|---|
| 0 | In situ | ~100% |
| I | Localized, thin | 99% |
| II | Localized, thick or ulcerated | 65-94% |
| III | Regional lymph nodes | 40-78% |
| IV | Distant metastases | 15-30% (traditional); 40-50%+ with immunotherapy |
Key Takeaway: Early detection is critical. When melanoma is caught early (localized), cure rate is 99%. Once it spreads, treatment becomes much more challenging, though immunotherapy has dramatically improved outcomes.
Living with Skin Cancer
Follow-Up Care
- BCC/SCC:
- Skin exams every 6-12 months for several years
- 35-50% develop another skin cancer within 5 years
- Lifetime monitoring recommended
- Melanoma:
- Stage 0-I: Every 6-12 months for 5 years, then annually
- Stage II-III: Every 3-6 months for 2-3 years, then every 6-12 months
- Stage IV: Every 3 months or as needed
- Imaging (CT, PET) for stage IIB and higher
Sun Protection After Diagnosis
- Even more critical after skin cancer diagnosis
- Previous cancer increases risk of new cancers
- Lifelong sun protection essential
- Vitamin D from diet/supplements, not sun exposure
Emotional Support
- Anxiety about recurrence is common
- Support groups available (Melanoma Research Foundation, AIM at Melanoma)
- Counseling can help with adjustment
- Many patients live full, normal lives after treatment
Frequently Asked Questions
Q: Can I get skin cancer if I have dark skin?
A: Yes, though less common. People with darker skin have lower rates but are often diagnosed at later stages. Bob Marley died from acral melanoma (on toe). People of color should still do skin checks and use sun protection. Melanoma in darker skin often appears in less sun-exposed areas like palms, soles, nail beds, mucous membranes.
Q: Should all moles be removed?
A: No. Most moles are harmless. Only remove moles that are suspicious (ABCDE criteria), changing, or bothersome. Removing all moles is impractical and unnecessary. Average person has 10-40 moles. Focus on monitoring for changes and having annual skin checks.
Q: Is sunscreen safe? I've heard it contains harmful chemicals.
A: Yes, sunscreen is safe and the benefits far outweigh any theoretical risks. FDA and dermatology organizations worldwide recommend daily sunscreen use. If concerned about chemical filters, use mineral sunscreens (zinc oxide, titanium dioxide). The proven harm from UV radiation vastly exceeds any unproven concerns about sunscreen ingredients.
Q: Will I need skin grafts after skin cancer removal?
A: Most skin cancer excisions heal with simple stitches. Larger removals or those in challenging areas may require skin flaps or grafts. Mohs surgery is designed to minimize tissue removal and often allows direct closure. Your dermatologist will discuss reconstruction options if needed. Cosmetic outcomes are generally excellent.
Q: Can tanning beds give you a "base tan" that protects you?
A: NO. This is a dangerous myth. A tan is your skin's injury response to UV damage. "Base tans" provide minimal protection (equivalent to SPF 3-4) while causing DNA damage that increases cancer risk. Tanning bed use before age 35 increases melanoma risk by 75%. There is no such thing as a "safe tan." Use self-tanning products if you want darker skin.
Q: If I've never had a bad sunburn, am I safe from melanoma?
A: No. While sunburns (especially in childhood) increase risk, cumulative UV exposure also matters. You can develop melanoma without ever having a severe burn. Additionally, ~25% of melanomas develop in areas with little sun exposure. Genetics, number of moles, and other factors also influence risk. Everyone should practice sun protection and skin monitoring.
Q: How long does it take for sun damage to turn into cancer?
A: Typically decades. BCC/SCC usually develop in people 50+, reflecting cumulative sun exposure over lifetime. Melanoma can occur at younger ages, especially with intense intermittent sun exposure or tanning bed use. DNA damage from UV radiation accumulates over years before cancer develops. This is why sun protection in childhood and young adulthood is so critical - preventing damage now prevents cancer later.
Q: Can skin cancer come back after treatment?
A: Local recurrence is uncommon with complete excision (5% for BCC with standard excision, <1% with Mohs surgery). However, 35-50% of people who've had one BCC/SCC develop another within 5 years (new primary, not recurrence). After melanoma, 15-40% experience recurrence depending on stage. This is why lifelong monitoring is essential. Having one skin cancer significantly increases your risk of developing additional skin cancers.
Q: Should I avoid the sun completely after skin cancer?
A: You don't need to become a hermit, but sun protection is critical. Use sunscreen daily, wear protective clothing, seek shade during peak hours (10 AM - 4 PM), wear wide-brimmed hats and sunglasses. You can still enjoy outdoor activities with proper precautions. Get vitamin D from diet/supplements rather than sun exposure. The goal is smart sun safety, not total sun avoidance, though some high-risk patients may need to be very cautious.
Q: Are there genetic tests for skin cancer risk?
A: Yes, for familial melanoma. If you have 2+ first-degree relatives with melanoma or many atypical moles plus family history, genetic counseling and testing for CDKN2A, CDK4 mutations may be appropriate. These account for ~10% of melanomas. Genetic testing can inform screening intensity and risk-reducing strategies. Most skin cancers are sporadic (not hereditary) and caused by UV exposure rather than inherited mutations.
Medical Disclaimer: This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Skin lesions should be evaluated by a qualified dermatologist. Self-diagnosis is not recommended. If you notice any suspicious skin changes, schedule an appointment with a healthcare provider promptly. Early detection and treatment of skin cancer dramatically improves outcomes.
Sources: This guide is based on National Comprehensive Cancer Network (NCCN) guidelines for melanoma and non-melanoma skin cancers, American Academy of Dermatology recommendations, American Cancer Society statistics, landmark clinical trials in melanoma immunotherapy and targeted therapy, and evidence-based dermatology literature. Content reviewed for medical accuracy and updated to reflect current standards of care as of 2025.