Eczema caused by defects in the skin could reduce the risk of
developing skin cancer, according to new research by King's College
London. The immune response triggered by eczema could help prevent
tumour formation by shedding potentially cancerous cells from the
skin.
There is ongoing debate surrounding allergic diseases and their
impact on the likelihood of developing cancer, with some studies
suggesting that eczema is associated with a reduced risk of skin
cancer. However, it is difficult to draw firm conclusions based on
studies of human populations because eczema symptoms vary in
severity and drugs used to treat the condition might also influence
cancer. The study is the first to show that allergy caused by the
skin defects could actually protect against skin cancer.
Skin cancer is a common and growing problem, accounting for one
in every three cancers diagnosed worldwide, according to the World
Health Organization. Recent findings suggest that malignant
melanoma, the most dangerous form of skin cancer, is now five times
more common in the UK than it was in the 1970s.
Eczema can result from the loss of structural proteins in the
outermost layers of the skin, leading to a defective skin barrier.
Genetically engineered mice lacking three skin barrier proteins
('knock-out' mice) were used in the King's study to replicate some
of the skin defects found in eczema sufferers.
The researchers compared the effects of two cancer-causing
chemicals in normal mice and mice with the barrier defect (the
knock-out mice). The number of benign tumours per mouse was six
times lower in knock-out mice than in normal mice. The findings
suggest that defects in the epidermal barrier protected the
genetically engineered mice against benign tumour formation.
Researchers found that both types of mice were equally
susceptible to acquiring cancer-causing mutations. However, an
exaggerated inflammatory reaction in knock-out mice led to enhanced
shedding of potentially cancerous cells from the skin. This
cancer-protective mechanism bears similarities to that which
protects skin from environmental assaults such as bacteria.
Professor Fiona Watt, Director of the Centre for Stem Cells and
Regenerative Medicine at King's, said: "We are excited by our
findings as they establish a clear link between cancer
susceptibility and an allergic skin condition in our experimental
model. They also support the view that modifying the body's immune
system is an important strategy in treating cancer.
"I hope our study provides some small consolation to eczema
sufferers - that this uncomfortable skin condition may actually be
beneficial in some circumstances."
Dr Mike Turner, Head of Infection and Immunobiology at the
Wellcome Trust, said: "Skin cancer is on the rise in many countries
and any insight into the body's ability to prevent tumour formation
is valuable in the fight against this form of cancer. These
findings that eczema can protect individuals from skin cancer
support theories linking allergies to cancer prevention and open up
new avenues for exploration whilst providing some (small) comfort
for those suffering from eczema."
The paper, Epidermal barrier
defects link atopic dermatitis with altered skin cancer
susceptibility, is published in eLife.