Skin carcinomas linked to other cancers

By Corin Kelly
Wednesday, 11 November, 2015

Non-melanoma skin cancers (NMSCs) are the most common cancers in Australia and account for seven out of every eight new cancers diagnosed. Unlike melanomas that are less common and more aggressive, NMSCs are relatively easy to treat and rarely spread to other parts of the body. People who do get non-melanoma skin cancers, however, particularly before the age of 25, are at a much greater risk of developing 30 other cancers, including breast, colon and lung cancers. This is according to research by Dr Rodney Sinclair and colleagues, published in Cancer Epidemiology, Biomarkers & Prevention.
Different cancers result from disruption of different molecular pathways, and it is now recognised that there are shared molecular mechanisms for cancers of the epithelial cells (skin, salivary glands breast, bowel, lung) and also between BCC and certain brain tumours. Disruption of one of these shared molecular pathways may lead to multiple cancers in different organs.
Like melanomas, NMSCs, develop in susceptible people (those with fair skin, red or blond hair, blue eyes and those susceptible to cancer in general) as a result of UV exposure.
UV exposure suppresses the immune system in the skin which is why some people get a cold sore after prolonged sun exposure. It also suppresses tumour surveillance by the immune system. This is the natural protective mechanism the body uses to fight developing skin cancers.

Risk of other cancers

Before the study, Dr Sinclair and his team hypothesised that people who developed skin cancers later in life did so as a result of accumulated sun exposure, while those who developed skin cancer at a younger age did so because of an increased susceptibility to cancer in general.
To investigate this, they stratified the risk ratios by age and discovered that young people with NMSC were more cancer-prone. The results showed that out of the 500,000 people in the NMSC group, 13.36% subsequently developed cancers compared with only 9.81% of the 8.8 million people in the control group.
They found that for those who had NMSC, the relative risk for developing cancers of the bladder, brain, breast, colon, liver, lung, pancreas, prostate, and stomach remained consistently elevated when compared to the control group for the entire period of the study, and the risk for cancers of the brain, colon, and prostate increased with time.
They also identified that those who had NMSC before the age of 25 were 53 times more likely to get bone cancer, 26 times more likely to get blood cancers, 20 times more likely to get brain cancer, and 14 times more likely to get any cancer excluding those of the skin.
The study shows that NMSC susceptibility is not only a marker of people who have spent too much time in the sun. It is also an important indicator of susceptibility to malignant tumours – and the risk is especially high among people who develop NMSC at a young age.
The recognition that NMSC patients are cancer-prone individuals, especially when diagnosed with their skin cancer at a young age, allows public health agencies to examine options to better target cancer screening.
This article was originally published on The Conversation. Read the original article.