According to a recent study by British Journal of Dermatology. Accordingly, the authors of the first large-scale, population-based comparison of 5-year survival by melanoma subtype argue that physicians should also consider melanoma morphology as a key prognostic indicator.1
“We hope that dermatologists, and the surgeons and pathologists with whom they work, will be more aware of the importance of accurate pathological diagnosis, both in the management of individual patients and in enabling a more accurate picture. of melanoma pathology and population-level survival,” said lead author Veronica Di Carlo, MSc. She is a research associate with the Cancer Survival Group in the Department of Non-Communicable Disease Epidemiology at the London School of Hygiene and Tropical Medicine in London, England.
Current clinical guidelines state that histology subtype is only an optional item to be included in pathology reports.2 “We hope that our results will encourage the reporting of the histological subtype of melanoma in the pathology report, as well as the other key characteristics such as size, location, thickness and ulceration,” Di Carlo said. .
Using data from over 1.5 million adults diagnosed with melanoma between 2000 and 2014 who participated in the CONCORD-3 trial,3 investigators found the following:
- Nodular melanoma (7% to 13% of melanomas worldwide) had the poorest prognosis anywhere. The estimated age-standardized 5-year net survival for patients diagnosed between 2010 and 2014 ranged from 72% to 80% in the United States, Canada, New Zealand and Australia, compared to 58% in Costa Rica and Poland.
- ALM accounted for less than 2% of cases in North America, Europe and Oceania, compared to 6% to 7% in Asia and Central and South America, including more than 10% in Korea, Singapore, Taiwan , Colombia, Costa Rica and Guadeloupe. , and Martinique. The age-standardized 5-year net survival for patients diagnosed with ALM between 2010 and 2014 ranged from 66% (Taiwan) to 95% (Belgium).
- Using national registries in Germany, Spain, and Norway, researchers estimated that, compared to superficial spreading melanoma, patients with nodular melanoma were at a 13.5-fold risk of death, 6, 7 times and 4.1 times higher, respectively, even after controlling for sex, age and stage at diagnosis. The corresponding figures for ALM were 10.8, 5.0 and 2.2.
The perception that the risk of melanoma is lower in dark-skinned people than in light-skinned people is believed to be one of the reasons for delayed diagnosis in dark-skinned people, Di Carlo said. Dermatology Times®. Since healthcare providers may often be less suspicious of melanoma in dark-skinned patients, she explained, providers may be less likely to offer regular skin exams. of the whole body.
“A high proportion of melanomas in dark-skinned people occur in areas of the body that are protected from the sun, such as the palms, soles of the feet and under the fingernails,” added Di Carlo. “Delays in the diagnosis of this subtype of melanoma are well documented and are likely due to the lesion’s hidden location, unusual clinical presentation, low public awareness, and misdiagnosis by healthcare professionals. health, especially when the lesion is not pigmented.”
For nodular melanoma, the American Joint Committee on Cancer staging guidelines omit this subtype based on the results of a single institution study published in 1978.4.5 However, a more recent US population-based study on superficial spread and nodular melanoma showed that morphology does indeed predict survival.6
To date, morphological classification has not been considered useful for prognosis, as it is believed that regardless of histologic subtype, the clinical progression of all melanomas proceeds similarly and behavior converges towards the metastasis.6.7 Therefore, Di Carlo and colleagues wrote, recommended treatment options do not differ between morphological subtypes at any given diagnostic stage.
Ignoring morphology also creates research challenges. The fact that approximately 42% of tumors in the study were classified as “malignant melanomas, unspecified” limited the interpretation of net survival estimates for all melanomas with specific morphological subtypes.
The study also underscores the need for health policies targeting specific populations in regions such as Asia and Latin America, where dangerous melanoma subtypes disproportionately occur, the authors wrote.
“Several countries in Latin America have implemented recommendations for protection against ultraviolet (UV) radiation, the main risk factor for cutaneous melanoma,” Di Carlo said. In Chile, employers are legally required to implement effective measures to protect workers from occupational exposure to UV rays, she added. “In Peru, legislation mandates the protection of children in schools by limiting activities that involve unprotected UV exposure, regulating school uniforms, and including education on the risks of UV exposure in educational programs. “
National skin cancer awareness campaigns have also been implemented in Argentina, Cuba, Panama, Peru and Uruguay, she added. In most Asian countries, on the other hand, these recommendations and awareness campaigns remain limited.
“To our knowledge,” added Di Carlo, “there are no awareness campaigns aimed at educating general practitioners and the public to recognize the early signs of acral lentiginous melanoma. Public health efforts to increase the Awareness of this rare but aggressive form of melanoma, combined with specific diagnostic training for clinicians, can reduce the time between the first consultation and a definitive diagnosis and lead to a better prognosis.
Di Carlo reports no relevant financial interests.
1. DiCarlo V, Stiller CA, Eisemann N, et al. Does the morphology of cutaneous melanoma explain international differences in survival? Results of 1,578,482 adults diagnosed between 2000 and 2014 in 59 countries (CONCORD-3) [published online ahead of print, 2022 Mar 29]. Br J Dermatol. 2022;10.1111/bjd.21274. doi:10.1111/bjd.21274
2. Swetter SM, Tsao H, Bichakjian CK, et al. Care guidelines for the management of primary cutaneous melanoma. J Am Acad Dermatol. 2019;80(1):208-250. doi:10.1016/j.jaad.2018.08.055
3. Allemani C, Matsuda T, DiCarlo V, et al. World Surveillance of Cancer Survival Trends 2000-14 (CONCORD-3): analysis of individual records of 37,513,025 patients diagnosed with one of 18 cancers from 322 population registries in 71 countries. Lancet. 2018;391(10125):1023-1075. doi:10.1016/S0140-6736(17)33326-3
4. Balch CM, Buzaid AC, Soong SJ, et al. New TNM melanoma staging system: linking biology and natural history to clinical outcomes. Semin Oncol Surgery. 2003;21(1):43-52. doi:10.1002/ssu.10020
5. Balch CM, Murad TM, Soong SJ, Ingalls AL, Halpern NB, Maddox WA. A multifactorial analysis of melanoma: prognostic histopathological features comparing Clark’s and Breslow’s staging methods. Anne Surg. 1978;188(6):732-742. doi:10.1097/00000658-197812000-00004
6. Lattanzi M, Lee Y, Simpson D, et al. Histological subtype of primary melanoma: impact on survival and response to treatment. J Natl Cancer Institute. 2019;111(2):180-188. doi:10.1093/jnci/djy086
7. Ackerman AB, David KM. A unifying concept of malignant melanoma: biological aspects. Hum Pathol. 1986;17(5):438-440. doi:10.1016/s0046-8177(86)80030-2