Does lightning strike twice?
“There is no substitute for a good history” is a phrase I heard a lot as a student, and this is a statement which still holds true today as potentially serious mistakes can be made when it is ignored. As part of the primary assessment, it is paramount to find out from the patient about their previous medical history and when it comes to the skin it is no exception.
As an illustration, it is always pertinent to ask patients about their skin cancer history. Particularly in older adults, skin cancer is extremely common and in the UK. Every year, around 147 000 new cases of basal cell and squamous cell carcinomas (also known as non-melanoma skin cancers or NMSCs) and about 15 000 cases of malignant melanoma occur in the UK (Cancer Research UK Statistics, 2020). Despite malignant melanoma being the least common of the three main skin cancers, it is responsible for 70% of the skin cancer-related deaths. Its incidence continues to rise – roughly doubling every ten years in many countries. Consequently, much research has been dedicated to studying the risk factors, its diagnosis and treatment.
Ultimately, this collected information should be borne in mind as patients with a history of melanoma are at an increased risk of developing a second primary, melanoma when compared to patients with no prior history (1). Consequently, such patients are regularly reviewed and follow up after diagnosis, not just for treatment but also to undergo checks for second lesions. So, what is the actual risk of developing a second melanoma?
A paper published in the Journal of the American Academy of Dermatology (2) has recently been published and investigated this question. As the authors suggest, previous studies have estimated that the risk of developing a second primary, melanoma in patients was between 2% - 20%, this data often being acquired retrospectively from cancer registries. In this new research, the authors follow a cohort (prospectively) to assess the risk of developing a second primary melanoma but also to see the best way to detect them as they arise. The two methods in this study were serial dermoscopy of existing lesions and total body photography as a means of detecting any new lesions that may arise. Consequently, they found that the five-year cumulative risk of developing a second, primary lesion was around 8%. This was particularly a risk for patients with fair skin, high mole counts or those with a lot of previous occupational sunlight exposure. Interestingly, the data analysed showed that the risk was highest in the first year after initial diagnosis (2.46%) and then it gradually reduced year upon year to 1.17% by year five. Both dermoscopy and total body photography were found to be of value in detecting any new lesions.
Other previous work has suggested those with their first melanoma before the age of 19 are at double the risk of developing a second melanoma (3). This also reported that 55% of second melanomas, in patients of all ages, arose in a different anatomical location to the first, with 44% of second melanoma even being a different sub-type to the first. As a final point, it is worth noting that it is known that patients with a history of NMSC’s are also at an increased risk of developing further malignancies including melanoma (4).
The clinical message of this research is a reminder that skin cancer history of our patients with both melanoma and non-melanoma is important and should remind us of the need to remain vigilant. Monitoring any lesions on the legs and feet for changes is a worthwhile step in patients we see regularly. If any are noted, rapid referral for further assessment is always advised.
1. Goggins WB, Tsao H. A population-based analysis of risk factors for a second primary cutaneous melanoma among melanoma survivors. 2003;97(3):639-43.
2. Lallas A, Apalla Z, Kyrgidis A, Papageorgiou C, Boukovinas I, Bobos M, et al. Second primary melanomas in a cohort of 977 melanoma patients within the first 5 years of monitoring. J Am Acad Dermatol. 2020;82(2):398-406.
3. Jung GW, Weinstock MA. Clinicopathological comparisons of index and second primary melanomas in paediatric and adult populations. Br J Dermatol. 2012;167(4):882-7.
4. Wheless L, Black J, Alberg AJ. Nonmelanoma Skin Cancer and the Risk of Second Primary Cancers: a Systematic Review. 2010;19(7):1686-95.