Skin cancer doesn’t happen overnight. It develops gradually as damaged cells multiply, invade nearby tissues, and, in some cases, spread to other parts of the body. Understanding the stages of skin cancer can help you recognize where the disease stands, what treatments are needed, and what to expect next.

Whether it’s basal cell carcinoma, squamous cell carcinoma, or melanoma, staging determines how far cancer has advanced. This guide explains the stages, key characteristics, and progression patterns of the three main types of skin cancer—so you can better understand the journey from early warning signs to advanced disease.

Why Staging Matters

Defines how advanced cancer is
Staging tells doctors how deep and widespread cancer has become. It’s based on several factors:

  • Tumor size and depth of invasion

  • Lymph node involvement

  • Metastasis (whether cancer has spread to distant organs)

Guides treatment choices
Knowing the stage helps doctors plan the best approach—whether that’s simple excision, radiation, immunotherapy, or systemic treatment.

Predicts outcomes
Early-stage skin cancers have excellent cure rates, while later stages may require complex treatments. The stage also helps estimate survival rates and guide follow-up schedules.

How Skin Cancer Staging Works

The TNM system
The most widely used system is the TNM classification, developed by the American Joint Committee on Cancer (AJCC). It evaluates:

  • T (Tumor): how large and deep the tumor is

  • N (Node): whether cancer has spread to lymph nodes

  • M (Metastasis): whether it has spread to other organs

Each letter receives a number (e.g., T1, N0, M0), and together they determine the overall stage (0–IV).

Different cancers, different rules
Melanoma, basal cell carcinoma (BCC), and squamous cell carcinoma (SCC) are staged differently because they grow and spread in unique ways. However, they share one key principle—the deeper the invasion, the higher the stage.

Stage 0: In Situ (Earliest Form)

Definition
Stage 0, or carcinoma in situ, means the cancer cells are confined to the outermost skin layer (the epidermis). They haven’t yet invaded deeper tissues.

Examples

  • Basal cell carcinoma in situ (very rare)

  • Squamous cell carcinoma in situ, also known as Bowen’s disease

  • Melanoma in situ—the earliest melanoma stage

What it looks like

  • A flat, scaly patch that may resemble eczema or psoriasis

  • Slight discoloration—pink, brown, or reddish

  • May feel rough or crusty but doesn’t typically bleed

Treatment and prognosis
Usually treated with simple surgical removal, cryotherapy, or topical medication. Prognosis is nearly 100% curable when treated early.

Stage I: Localized Growth

Definition
Cancer has begun to grow beyond the top skin layer but hasn’t spread to lymph nodes or distant organs.

For basal and squamous cell carcinoma:

  • The tumor is small (under 2 centimeters).

  • It hasn’t invaded nearby structures like bone or muscle.

For melanoma:

  • The tumor is up to 2 millimeters thick.

  • No ulceration (open sore) or spread to lymph nodes.

Symptoms and appearance

  • A mole that changes shape or color

  • A raised or crusted bump that bleeds easily

  • Persistent sore or pink patch that doesn’t heal

Treatment

  • Surgical excision or Mohs surgery for precise removal

  • Topical therapy or curettage and electrodessication for small, superficial tumors

  • Close monitoring for recurrence

Prognosis
Five-year survival for early-stage skin cancers exceeds 95–99%, especially when removed completely.

Stage II: Larger or Deeper Tumors

Definition
The tumor has grown thicker or deeper into the skin but still hasn’t reached lymph nodes or distant organs.

For basal and squamous cell carcinoma:

  • Tumor is larger than 2 centimeters or has invaded deeper layers (dermis, subcutaneous fat).

  • Some may show high-risk features—rapid growth, nerve invasion, or poor differentiation.

For melanoma:

  • The tumor is 2–4 millimeters thick, with or without ulceration.

  • No lymph node involvement.

Symptoms and appearance

  • Rapidly enlarging lump or sore

  • Lesions that bleed, crust, or ooze

  • Pain or itching at the site

Treatment

  • Wide surgical excision (removing tumor with a margin of healthy tissue)

  • Reconstructive surgery for larger defects

  • Radiation therapy if surgery isn’t possible

  • In select cases, immunotherapy may be considered for melanoma

Prognosis
Still favorable—five-year survival is 90–95%, depending on tumor depth and ulceration.

Stage III: Regional Spread

Definition
Cancer has spread to nearby lymph nodes or adjacent tissues but not to distant organs.

For basal and squamous cell carcinoma:

  • Tumor may invade muscle, bone, or cartilage.

  • One or more nearby lymph nodes contain cancer cells.

For melanoma:

  • Cancer has spread to regional lymph nodes or small nearby skin deposits (“in-transit metastases”).

  • The primary tumor may be ulcerated or thick (>4 mm).

Symptoms

  • Enlarged lymph nodes near the original tumor (firm, painless lumps)

  • Skin nodules around the main lesion

  • Persistent pain, swelling, or limited mobility if cancer invades deeper structures

Diagnostic tests

  • Sentinel lymph node biopsy

  • CT, MRI, or PET scans to map spread

  • Blood work for overall health assessment

Treatment

  • Surgical removal of primary tumor and affected lymph nodes

  • Radiation therapy to kill remaining cancer cells

  • Immunotherapy (e.g., pembrolizumab, nivolumab) for melanoma

  • Targeted therapy for cancers with specific gene mutations

Prognosis
Five-year survival depends on the number of affected lymph nodes and tumor size—typically 60–85% for melanoma and slightly higher for non-melanoma types.

Stage IV: Metastatic Disease

Definition
This is the most advanced stage, where cancer has spread to distant organs such as the lungs, liver, brain, or bones.

How it happens
Cancer cells travel through the bloodstream or lymphatic system, forming secondary tumors in other parts of the body.

Common symptoms

  • Persistent fatigue or unexplained weight loss

  • Shortness of breath or cough (lung involvement)

  • Jaundice (liver involvement)

  • Headaches or neurological symptoms (brain metastasis)

Diagnostic tools

  • PET-CT scans to identify spread throughout the body

  • MRI for brain and soft tissue metastases

  • Biopsy of secondary tumors for confirmation

Treatment options

  • Systemic immunotherapy (checkpoint inhibitors like pembrolizumab, nivolumab)

  • Targeted therapy for tumors with BRAF or MEK mutations

  • Chemotherapy (less common now but still used in advanced cases)

  • Palliative radiation to relieve pain and improve quality of life

Prognosis
While stage IV is serious, new treatments have extended survival dramatically. Many patients now live years longer than in the past, especially with immunotherapy success.

Progression by Cancer Type

Basal cell carcinoma (BCC)

  • Grows slowly and rarely spreads (metastasis is extremely uncommon).

  • However, untreated lesions can invade deep tissues, causing disfigurement.

  • Early removal ensures excellent outcomes.

Squamous cell carcinoma (SCC)

  • Can grow faster and invade nerves or lymph nodes.

  • High-risk SCCs (on lips, ears, or in immunocompromised people) require close follow-up.

Melanoma

  • The most aggressive type.

  • Can spread even when small and thin.

  • Regular self-checks and prompt biopsy of suspicious moles are crucial.

Restaging After Treatment

Sometimes, skin cancer is restaged after surgery or additional imaging to confirm whether it has been fully removed or if hidden spread exists.

Post-surgical evaluation includes:

  • Pathology margin review (checking if cancer was fully excised)

  • Imaging scans for deeper invasion

  • Molecular tests for residual disease

Restaging helps guide ongoing treatment, such as radiation or immunotherapy.

Survival and Outlook

Survival by stage (melanoma example):

  • Stage 0–I: 99% five-year survival

  • Stage II: 90–95%

  • Stage III: 60–85%

  • Stage IV: around 30–40% (improving with new treatments)

Non-melanoma (BCC & SCC):
Nearly all early cases are cured, but recurrence risk remains if sun protection is neglected.

Lifestyle and follow-up

  • Perform monthly self-exams

  • See a dermatologist every 6–12 months

  • Maintain sun-safe habits for life

Emotional and Physical Recovery

Coping with diagnosis
Hearing you have skin cancer—at any stage—can be overwhelming. Emotional support, counseling, and patient groups can help you navigate the journey.

Skin health after treatment

  • Follow your doctor’s wound care instructions

  • Use scar creams and sun protection daily

  • Maintain a healthy diet and stay active for immune resilience

Living confidently post-diagnosis
Many survivors go on to live long, healthy lives. Early detection, consistent follow-up, and preventive care make a huge difference.

Key Takeaways

  • Staging defines the extent of skin cancer and guides treatment.

  • Stage 0–II: localized and highly curable.

  • Stage III–IV: advanced, requiring multidisciplinary care.

  • Early detection drastically improves outcomes across all skin cancer types.

Knowing your stage isn’t about fear—it’s about power. The more you understand your condition, the better prepared you are to take control of your care.