Eczema is a common allergic skin condition that afflicts many people. However, a new study from King’s College London suggests that the immune response triggered by this allergic dermatitis can reduce the risk of skin cancer by encouraging the shedding of potential skin cancer cells and preventing tumor formation. The issue of the impact of allergic diseases on cancer has been debated. Some epidemiological studies have suggested that eczema may be associated with skin cancer risk, but it is difficult to draw definitive conclusions because of the marked differences in the degree of eczema development in the sample populations used for these studies and the possibility that the medications used to treat patients may also affect cancer incidence. The new study from King’s College London, however, confirms for the first time that allergies caused by this skin defect can indeed reduce the risk of developing skin cancer. In the study, researchers removed three barrier proteins from the skin epidermis of mice by a knockout technique, replicating an epidermal barrier defect similar to that of eczema patients. The researchers then used two cancer-causing chemicals on normal mice and this epidermal barrier-deficient mice, and they found that both types of mice were susceptible to cancer-causing mutations, but that the skin inflammatory response in the epidermal barrier-deficient mice caused potential cancer cells to be shed from the skin, with the result that they produced six times fewer tumors in their bodies than normal mice. This suggests that a defective epidermal barrier reduces the chance of tumor formation and protects mice from cancer. The researchers noted that the experimental mouse model study demonstrated that there is indeed an association between cancer susceptibility and skin sensitization, a finding that suggests that modifying the human immune system should be an important strategy for cancer treatment. At the same time, this finding also suggests that the distress of skin inflammation is not all bad, and that suffering from a small disease prevents a big one, which is a small consolation for those suffering from eczema.