Moles, Sunspots and Skin Cancers

Our sun is a massive radioactive furnace emitting radiation which bathes the Earth and every organism living above ground. This radiant energy in the form of light, heat and invisible forms of radiation such as ultraviolet light powers the forces of climate and thereby creates the environment which enables life to exist and evolve.

That same radiant energy can also do damage, as anyone who has experienced sunburn can verify. In fact the effects of the sun's radiation and in particular it's ultraviolet radiation (light which the naked eye cannot see) are now understood much better than a generation ago thus leading to public information campaigns such as the "Slip, Slap, Slop" campaign.

It is now common knowledge that exposure to the ultraviolet radiation in sunlight with cause cumulative damage to tissues, in particular sun and eyes. Short intense exposure can cause acute "radiation damage" otherwise known as sunburn. (Welders sometimes develop "welders flash burn" to their eyes when electric arc welders, which produce high levels of the same ultraviolet radiation in the arc, are used with inadequate eye protection!)

Repeated exposure of skin to high intensity ultraviolet light/radiation over a long time causes accumulation of damage to the important structures of the skin, in particular the supportive elastic tissue ("elastin") and collagen which provides strength but little elasticity. For this reason people who repeatedly expose themselves to the sun or to ultraviolet radiation in solariums in the hope of developing a suntan will develop premature wrinkling and sagging of their skin!

In addition, cells which provide immunity in the skin start to die off. These cells probably help to remove cancerous cells in the skin as soon as they develop and their progressive loss is one reason why precancerous changes develop in areas of skin repeatedly exposed to sunlight.

Precancerous changes in the skin are sometimes called "solar keratoses" or "actinic keratoses" and are commonly found on the face and neck as well as on forearms and the back of hands. They may be present as a solitary lesion or they may exist in huge numbers. They commonly produce patches of scaling skin which may build up into quite thick scab-like spots or "lesions". They may cause itching but they are considered relatively harmless. Each and every one of these spots probably has only a 1% chance of one day changing into a skin cancer. However if you have a hundred of them that clearly increases your risk to virtually a dead cert (if you'll forgive the unfortunate pun!). It is now known that many solar keratoses will heal and disappear if continuing exposure to ultraviolet light is reduced dramatically or stopped entirely by measures such as covering up, avoiding being outdoors during the times of the day when UV levels are at their highest, and by using UV blockout whenever one is outdoors.

(Click on one of these many solar keratoses to see a closeup image.)



When a solar keratosis does change into a skin cancer it almost always becomes what is known as a "squamous cell" cancer or carcinoma. The major way to differentiate between a solar keratosis and a squamous cell cancer is that the cancer commonly becomes painful and tender and may bleed. Squamous cell cancers will eventually invade deep into and under the skin if they aren't removed early enough and after invasion into deeper tissues they may then spread to the lymph glands and travel throughout the body thereby becoming incurable! The trick is to spot them and remove them while they are still small, non-invasive and curable.




Another form of skin cancer which appears in areas of skin damaged by sunlight is the "basal cell cancer" or "BCC". This type of cancer grows very slowly and slowly enlarges in all directions. As it enlarges it commonly forms deep ulcers in its centre which can bleed and become infected. They never spread to other parts of the body and they only do their harm by slowly growing and damaging underlying tissues. For example the author has seen one which had grown to the size of a small plate over 10 years. It was eventually removed by quite major surgery.




(Click on the skin cancer in the image - if you can spot it! - to see a closeup)

The most vicious and most feared (with justification) form of skin cancer is the "melanoma" which usually but not always is darkly pigmented and mostly but not always develops in areas of skin repeatedly exposed to sunlight. People who sustained sunburn during early childhood are at particular risk of developing melanomas but they can arise in areas of the skin which are rarely if ever exposed to sunlight and can even arise from within the eyeball and inside the bowel! Fortunately these instances are quite rare and overall, melanomas are much less common than other forms of skin cancer (fortunately!)

Melanomas commonly develop from pre-existing moles or "nævi" which may have been present for many years but suddenly start to change with an increase in all dimensions including thickness as well as increasing pigmentation, irregularity and eventually recurrent bleeding and itching.

(Click on the melanoma in the image to see a closeup)

Melanomas are deadly because they spread rapidly and have often already spread to other parts of the body before patients attend their doctors! The risk of invasion and spread is directly related to the thickness of the melanoma as measured by the medical specialist or "pathologist" who examines the cancer under a microscope after the melanoma has been removed. Very thin melanomas have a high rate of cure by simple removal (>95%) while thick lesions (>1.0mm thick) have often spread to lymph glands and beyond (bones, liver, brain, lung) by the time they are removed!

Removal then isn't really helpful in prolonging life and most major forms of anticancer therapy such as chemical poisoning ("chemotherapy") and radiotherapy don't work with melanomas! The most promising research underway at present is exploring ways of using the body's immune system to find and kill melanoma cells throughout the body.

Prevention is the BEST treatment: it is important for parents to instil into their children a strong respect for the dangers of too much exposure to sunlight. This is best done by setting an appropriate example with parents protecting their own skin with adequate clothing, UV blockout lotions or creams and trying to avoid being outdoors at certain times of the day when UV levels are at their maximum. Parental behaviour is the strongest model for children's behaviour!

Watch your spots: many people have moles. Some have so many it's just impossible to keep tabs on every one and to know exactly what each of the individual moles looks like. For these people it is reasonable to have regular skin checks performed by a doctor and sometimes even having photographs taken to document the appearance of moles on special areas such as the back. Then any change in appearance of one particular mole is more likely be noticed at an earlier stage than if one relies solely on memory (even the doctor's memory!). Report to your doctor if a new skin lesion appears or if a sore doesn't seem to heal in a reasonable period of time.

(The photos shown on this and other pages on this website were taken using our surgery's first digital camera, an Olympus Camedia 1000 with only 0.85 megapixels! Despite having what is now considered to be a very low resolution it has been used to take several thousand photos of excellent quality. The surgery now has several other digital cameras including a Nikon Coolpix 4500 which is mostly used with a Heine Dermatoscope to allow highly magnified images of pigmented lesions (moles) to be documented so that the risk of malignancy can be assessed with greater accuracy than merely using the naked eye. We also have a Nikon Coolpix 5700 camera which has an excellent "macro" or close-up function and this is routinely used for most pictures nowadays.

The digital images can be immediately transferred from the camera to the computer and examined within seconds of transfer to the computer in order to check whether the photos are acceptable in regards to focus, lighting, etc. Assuming that the photos are acceptable for future reference, the images are stored in a computer on the surgery's network and are accessible with a double-click from within a patient's medical record. For security they're backed up onto CD ROM. It's truly marvellous technology and helps us provide optimal care for our patients!)