A team of US scientists have found that people who develop a common form of skin cancer, may have an increased risk of other forms of cancer in the future. The scientists, from Stanford University School of Medicine in California, published their research in JCI Insight and the article is free to access.
The study recruited 61 patients who were being diagnosed with basal cell carcinoma (BCC) on a more regular than usual basis. The patients’ DNA was examined for their repair qualities. The study also undertook a case-control retrospective review to examine the association of other cancers with the development of a number of BCC, checking cases on a large US medical insurance claims database. This database included 13, 264 patients who had developed 6 or more BCCs during 2007 - 2011.
Cancer will be diagnosed in at least 1 in 5 people in the US and is the the second leading cause of death. Up to 10% of cancers are hereditary, occurring in people who may be genetically disposed to developing cancer. Breast, ovarian and colon cancers have been identified as being linked to family history. If people have a hereditary factor that may increase their risk of getting cancer, then identifying those people is a first step to offering screening which may help reduce the risk of getting a cancer that could cause death. The researchers were concerned, however that screening everyone would be too expensive and that it is difficult to find definitive clinical signs of problems with DNA repair mechanisms.
The scientists recognised that the skin is very dependant on the DNA repair mechanisms when it is exposed to UV light which can cause cancers. If the repair stops working, then patients may develop an increased number of skin cancer tumours. UV exposure causes basal cell carcinoma (BCC) which is a benign skin cancer. It develops in over 3 million US people every year. The scientists guessed that if people were developing over a particular number of basal skin cancer tumours, then this could be used as a clinical marker of possible underlying problems in DNA repair. The people they recruited for this study were among the top 5% of patients who were being seen at Stanford Hospital and Clinics for BCC. Most of the patients were male, European and averaged 68.9 years. The number of skin cancer tumours, confirmed by biopsy varied from 6 to 65, but each patient averaged 11. The average age of the patients when first diagnosed with cancer, was 44 years but 10 patients had developed the first tumour before they were 30.
Of the patients in the study, 12 patients were found to have recognised genetic mutations which predisposed them to cancer. 21 of the patients had a history of additional cancer. These included invasive and hematologic melanomas, breast, colon and prostate cancers. This group were shown to have a higher risk (3 times more likely) of developing another type of cancer, particularly invasive melanomas. The patients also had a higher risk of developing lymphoma and leukaemia.
The data from the insurance database also confirmed that people who had a certain number of BCC, were also more likely to develop further cancers after developing BCC. The higher the number of skin cancer tumours, the more likely it was that patients would develop another kind of cancer.
The scientists suggested that the appearance and diagnosis of basal cell carcinoma could be taken as a low-risk clinical sign that a patient may have a genetic predisposition to cancer, and that this could be used to test people for these genetic markers and monitor more closely. The scientists suggested that further study may be needed to understand how best to test for a number of cancer-related genes, before the method is implemented more widely.
Cho, H.G., et al., Frequent basal cell cancer development is a clinical marker for inherited cancer susceptibility, JCI Insight, August 2018