It is well-known that most skin cancer comes from being exposed to sunlight. But is sun exposure the only way to get skin cancer? No, it’s not.

Basal cell carcinoma (BCC) and squamous cell carcinoma (SCC) are the most common non-melanoma skin cancers. A history of sunburn or sun exposure increases the risk of BCC and with SCC. Risks are mostly linked to a lifetime of sun exposure.

Yet some skin cancers appear on places that never see the sun — between the toes, the soles of the feet and around the genitals. Such an occurrence is more likely to be a melanoma, which is the most dangerous type of skin cancer.

There are several causes of both melanoma and non-melanoma cancers that aren’t due to the sun.

Cancer can be caused by inherited genes or a family history. According to former Cancer Council Australia CEO, Professor Ian Olver, around 10 percent of melanomas result from family history of melanoma. This was reported in an ABC Health & Wellbeing article.

Tanning beds may be the culprit of increasing the risk of non-melanoma skin cancer, wrote CancerResearchUK.org.

Certain skin conditions can be behind some people developing skin cancer.

Whereas psoriasis isn’t a risk, some of its treatments are. The ones that employ ultraviolet light may increase the risk of non-melanoma skin cancer.

The same case holds true with chronic eczema. Ultraviolet light treatments and the drug methoxsalen can also increase the risk of non-melanoma skin cancer.

Some birthmarks found in the skin’s outer layer can increase the risk of developing BCC. These BCC cancers typically stay in the outer layers and don’t spread.

Gorlin syndrome is a rare genetic condition which starts at birth, and can result in the development of BCC.

For those who have undergone an organ or bone marrow transplant, and who take medication to stop rejection, there is an increased risk of developing a skin cancer in the future. The risk will increase the longer one takes that medication.

People with HIV or AIDS may also have an increased risk of non-melanoma skin cancer. This could stem from their compromised immune systems.

Inflammatory diseases such as inflammatory bowel disease or rheumatoid arthritis may increase the risk of skin cancer. Cancer could be caused by the condition itself, the medication used to subdue the immune system, or both.

Long-term radiation exposure can somewhat increase the risk of non-melanoma skin cancer. So can contact with different chemicals such as coal tar, soot, pitch, creosote, arsenic and shale oils, as well as petroleum products such as mineral oil or motor oil, said CancerResearchUK.org.

Reviewed May 13, 2016
by Michele Blacksberg RN
Edited by Jody Smith