Why Skin Cancer Happens and when to see your GP.

Dr Olivia
Nov 2
2 min read

Skin cancer is the most common cancer in Australia — but also one of the most preventable. To protect yourself, it helps to understand why skin cancer develops and how to recognise early warning signs before they become serious.

1. What Causes Skin Cancer

The main cause of skin cancer is ultraviolet (UV) radiation from the sun or artificial sources like tanning beds. UV rays damage the DNA inside skin cells. Over time, this damage builds up. When the body’s natural repair system can no longer fix it, abnormal cells begin to multiply, forming a tumour.

There are two key types of UV rays:

UVA rays – penetrate deeply and cause long-term skin ageing and DNA changes.
UVB rays – cause sunburn and are the main trigger for skin cancer.

Even small amounts of daily, unprotected exposure can contribute to DNA damage. The effects are cumulative — your skin “remembers” every burn and tan.

2. Common Risk Factors

Some people are more prone to developing skin cancer, including those who:

Have fair skin, freckles, or light eyes
Have a history of severe sunburns or regular sun exposure
Use tanning beds
Have a family history of skin cancer
Take immune-suppressing medications or have a weakened immune system
Are over 40 years old, when accumulated sun exposure begins to show

3. The Main Types of Skin Cancer

Basal Cell Carcinoma (BCC) – slow-growing; often looks like a pearly lump or scaly patch.
Squamous Cell Carcinoma (SCC) – may appear as a red, crusted, or ulcerated spot; can spread if untreated.
Melanoma – the most dangerous form; can spread quickly and become life-threatening if not detected early.

4. When to See Your GP

You should book a skin check with your GP or skin cancer doctor if you notice:

A new mole or spot that looks different from your others
A changing mole — in size, shape, or colour
A spot that bleeds, crusts, or doesn’t heal within 4–6 weeks
A mole with irregular borders, multiple colours, or asymmetry
A persistent sore, lump, or scaly patch that grows over time

The ABCDE rule can help you remember what to look for in moles:

A – Asymmetry: one half doesn’t match the other
B – Border: edges are irregular or blurred
C – Colour: multiple shades of brown, black, or red
D – Diameter: larger than 6mm
E – Evolving: changing in size, colour, or texture

Even if a spot looks small or painless, it’s important to have it checked — early detection saves lives.

5. Prevention Is Always Better

Protecting your skin every day makes the biggest difference:

Use broad-spectrum SPF 30+ or higher sunscreen daily
Wear long sleeves, wide-brimmed hats, and sunglasses
Seek shade during peak UV hours (10 am – 3 pm)
Avoid tanning beds
Schedule annual skin checks, especially if you have multiple risk factors

Key Message

Skin cancer happens when UV radiation damages the DNA in skin cells, causing them to grow out of control. But most cases can be prevented or treated early. By protecting your skin and seeing your GP promptly about any new or changing spot, you can greatly reduce your risk and ensure healthy skin for life.