Pediatric, Adolescent Melanoma Uptick Seen in Finland

Although melanoma incidence has been reported in Europe overall for the past several decades, specific numbers on the cancer’s incidence in Finland, as well as disease trends, have remained unknown.

Cutaneous melanoma is on the rise in Finland, according to new study findings published in Annals of Medicine.

Over a 24-year period (1990-2014), the study authors investigated the incidences of pediatric and adolescent melanoma. Their retrospective analysis included data from the Finnish Cancer Registry (FCR) on 122 patients who received a diagnosis of cutaneous melanoma between ages 0 and 19 years. Time-related differences were evaluated by years 1990 to 2002 and 2003 to 2014.

“The associated clinical and histopathological characteristics to reveal temporal trends, such as changes in diagnostic sensitivity of Spitzoid melanomas,” was also investigated, they added.

In addition to the patient records reviewed, dermatopathologists re-evaluated 73 archived primary melanoma samples for comparison and diagnostic accuracy. Melanoma incidence was reported per 1 million population, and a subanalysis compared outcomes among 2 age groups: 0 to 11 years and 11 to 19 years.

There was a 5.6% (95% CI, 2.7%-8.6%) annual increase seen in age-adjusted melanoma incidence over the course of the entire study period, which the authors deemed to be statistically significant. From 1990 to 2000, the increase was fairly consistent. It then took a very slight dip until 2005, at which point there was a sharp increase.

Overall, per 1 million population, the age-adjusted annual incidence jumped more than 4-fold over the course of the study. Compared with 1990 to 1994, during which the incidence rate was 1.4 cases/1 million, by 2010 to 2014, this had jumped to 5.8 cases/1 million—after tumor misclassifications in the cancer registry were corrected via review.

Broken out by age range, individuals aged 11 to 19 years had a more prominent age-adjusted increase in melanoma incidence compared with their younger study counterparts.

Of the 73 archived samples that were re-evaluated, 56 were confirmed to be malignant melanoma, with “samples that were nonmalignant according to both dermatopathologists considered as originally misclassified in the FCR data.” Findings from these 56 samples were then compared for the 2 study periods, and the following results were seen:

  • Sentinel lymph node biopsy (SNLB) was performed in more cases from 2003-2014 vs 1990 to 2002: 68% vs 5.6%
  • Tumors tended to have a higher grade if they were diagnosed in 2003-2014, but melanoma-related death were more frequent in 1990-2002
  • The median follow-up in 1990-2002 was more than 3 times as long vs 2003-2014: 18.0 (range, 2.6-25.4) vs 5.3 (range, 0.58-14.8) years

No differences were seen between the time periods in Clark level, Breslow thickness, ulceration, or mitotic rate; proportions of melanomas in the head and neck, trunk, upper and lower extremities; melanoma location by age or sex; melanomas in sun-exposed or non–sun-exposed areas; risk of melanoma-related death (HR, 1.53; 95% CI, 0.30-7.88; P = .611); or proportion of Spitzoid malignancies.

However, among the Spitzoid malignancies vs other melanoma types, age at diagnosis was younger (14.5 vs 17.4 years), more were diagnosed in lower extremities (49% vs 26%), tumor stage and Clark level were higher, BRAF V600E–positivity was less frequent (35.1% vs 68.4%), and SLNB results were more often positive (55% vs 14%).

The authors say the rise in cases per 1 million could be due to actual melanoma incidence change, diagnostic criteria/register coverage changes, or greater UV exposure, in particular that related to recreational travel. They encourage the use of studies that incorporate archived material, because these “are valuable in highlighting potential clinicopathological trends in cancer epidemiology.”

Reference

Rousi EK, Kallionpää RA, Kallionpää RE, et al. Increased incidence of melanoma in children and adolescents in Finland in 1990-2014: nationwide re-evaluation of histopathological characteristics.Ann Med. 2022;54(1):244-252.doi:10.1080/07853890.2022.2026001