Melanoma Incidence in Nordic Countries

With special focus on Norway

Raju Rimal

20 June 2023

Melanoma

• Cutaneous melanoma (CM) is the most aggressive and lethal form of skin cancer.

• It can be cured if caught and treated early but if left untreated, it may spread to other parts and can be fatal.

• Melanoma has increased dramatically in fair skinned population worldwide.

• Norway is ranked fifth in incidence and third in mortality worldwide.

Research Objective

To explore melanoma incidence and mortality in nordic countries by sex and their trend over 40-years period from 1980–2020.

Research Questions

1. Is there similar increase in melanoma incidence and mortality in Nordic countries?

2. Do men and women have similar incidence and mortality due to melanoma?

Data, Materials, and Methods

NordCan 2.0 Website

Data collection (NordCan 2.0)

id	sex	type	cancer	country
1	Male	Incidence	Melanoma	Denmark
2	Male	Incidence	Melanoma	Denmark
3	Male	Incidence	Melanoma	Denmark
4	Male	Incidence	Melanoma	Denmark
5	Male	Incidence	Melanoma	Denmark
6	Male	Incidence	Melanoma	Denmark

year	asr_w	asr_e	asr_n	crude_rate	count	population
1980	11.85	12.74	13.45	12.36	196	1585436
1981	10.89	12.15	13.07	11.98	191	1593815
1982	12.19	13.11	14.08	13.11	210	1601416
1983	13.38	14.48	15.18	14.29	230	1609960
1984	13.84	15.34	16.00	14.77	239	1618038
1985	13.74	14.84	15.33	14.38	234	1626757

API: https://gco.iarc.fr/gateway_prod/api/nordcan/v2/92/data/population/{type}/{sex}/({country})/({cancer})/?ages_group=5_17&year_start=1980&year_end=2020&year_grouped=0

Nordic countries included

🇳🇴 Norway

🇸🇪 Sweden

🇩🇰 Denmark

🇫🇮 Finland

Methods

Crude Rate:

\[ \mathtt{rate} = \frac{\texttt{# number of cases}}{\texttt{# persons exposed}} \]

Poisson regression model:

model <- glm(
  formula = count ~ year + offset(log(population)), 
  data = melanoma,
  family = poisson(link = "log")
)

Segmented regression model:

sgmt_model <- segmented(model, npsi = 2)

Results

Incidence (Norway and Finland)

Norway has higher melanoma incidence and mortality than Finland.

Incidence (Norway and Finland)

Norway has higher melanoma incidence and mortality than Finland.

Incidence (Norway and Finland)

Norway has higher melanoma incidence and mortality than Finland.

Comparison (All countries)

Finland has lowest melanoma incidence and mortality in both sexes

Norway has highest melanoma mortality followed by Sweden in both sexes

Denmark has surpassed both Norway and Sweden in melanoma incidence in the recent years

Comparison (All countries)

A plateau period was observed in melanoma incidence in Norway.

Most countries has raise in melanoma incidence after 2005.

A declining melanoma moratlity was observed in all countries in recent years.

Model

Annual percentge change (APC)

APC within segments

Segment	Incidence		Mortality
	Female	Male	Female	Male
Denmark
1	2.73 (2.42, 3.04) 1980-2002	3.53 (3.22, 3.84) 1980-2004	10.46 (-6.14, 29.98) 1980-1982	0.62 (0.08, 1.16) 1980-2004
2	6.92 (5.8, 8.04) 2002-2011	9.86 (7.38, 12.39) 2004-2009	0.65 (0.26, 1.03) 1982-2014	4.02 (0.85, 7.29) 2004-2012
3	1.79 (1.18, 2.41) 2011-2020	3.12 (2.55, 3.69) 2009-2020	-1.98 (-6.26, 2.5) 2014-2020	-2.14 (-4.06, -0.17) 2012-2020
Norway
1	3.92 (2.9, 4.96) 1980-1990	5.49 (4.32, 6.67) 1980-1991	1 (0.18, 1.84) 1980-2000	17.06 (-0.38, 37.54) 1980-1982
2	-0.1 (-1.26, 1.08) 1990-1999	0.45 (-0.44, 1.35) 1991-2002	2.7 (1.31, 4.1) 2000-2013	1.79 (1.4, 2.19) 1982-2011
3	3.62 (3.35, 3.88) 1999-2020	4.39 (4.08, 4.69) 2002-2020	-5.01 (-8.14, -1.76) 2013-2020	-1.97 (-3.79, -0.12) 2011-2020

Model

Incidence model:

Code

mdl_inc <- glm(
  data = data,
  formula = count ~ year + sex + country,
  offset = log(population),
  family = poisson(link = "log"),
  subset = type == "Incidence"
)

Mortality model

Code

mdl_mor <- glm(
  data = data,
  formula = count ~ year + sex + country,
  offset = log(population),
  family = poisson(link = "log"),
  subset = type == "Mortality"
)

• Incidence model summary
• Mortality model summary

broom::tidy(mdl_inc, conf.int = TRUE, exponentiate = TRUE) %>% 
  modify_at(c(2:4, 6:7), round, 3)
# A tibble: 6 × 7
  term           estimate std.error statistic  p.value conf.low conf.high
  <chr>             <dbl>     <dbl>     <dbl>    <dbl>    <dbl>     <dbl>
1 (Intercept)       0         0.385   -205.   0           0         0    
2 year              1.04      0        185.   0           1.04      1.04 
3 sexMale           1.01      0.004      2.42 1.55e- 2    1.00      1.02 
4 countrySweden     0.89      0.006    -20.6  4.67e-94    0.88      0.9  
5 countryDenmark    0.951     0.006     -8.08 6.31e-16    0.939     0.962
6 countryFinland    0.617     0.007    -68.4  0           0.609     0.626

broom::tidy(mdl_mor, conf.int = TRUE, exponentiate = TRUE) %>% 
  modify_at(c(2:4, 6:7), round, 3)
# A tibble: 6 × 7
  term           estimate std.error statistic   p.value conf.low conf.high
  <chr>             <dbl>     <dbl>     <dbl>     <dbl>    <dbl>     <dbl>
1 (Intercept)       0         0.847     -40.4 0            0         0    
2 year              1.01      0          28.9 6.54e-184    1.01      1.01 
3 sexMale           1.46      0.01       38.0 0            1.44      1.49 
4 countrySweden     0.831     0.013     -14.3 3.31e- 46    0.81      0.853
5 countryDenmark    0.807     0.015     -14.6 3.42e- 48    0.785     0.831
6 countryFinland    0.59      0.016     -32.7 6.16e-234    0.572     0.609

Wrap-up

Summary

• Melanoma incidence and moratlity is increasing in all countries
• Norway has highest mortality rate through out the period and has highest increase in both incidence and mortality.

• Melanoma incidence increased rapidly in Denmark between 2002 and 2011 in women and 2004-2009 in men surpassing Norway.

• Mortality is decreasing in all countries in recent period.

References

Engholm, Gerda, Jacques Ferlay, Niels Christensen, Freddie Bray, Marianne L. Gjerstorff, Åsa Klint, Jóanis E. Køtlum, Elínborg Ólafsdóttir, Eero Pukkala, and Hans H. Storm. 2010. “NORDCAN – a Nordic Tool for Cancer Information, Planning, Quality Control and Research.” Acta Oncologica 49 (5): 725–36. https://doi.org/ch4598.

Larønningen, S., J. Ferlay, H. Beydogan, F. Bray, G. Engholm, M. Ervik, J. Gulbrandsen, et al. 2022. “NORDCAN: Cancer Incidence, Mortality, Prevalence and Survival in the Nordic Countries, Version 9.2 (23.06.2022).” 2022. https://nordcan.iarc.fr/.

Muggeo, Vito M. R. 2008. “Segmented: An r Package to Fit Regression Models with Broken-Line Relationships.” R News 8 (1): 20–25. https://cran.r-project.org/doc/Rnews/.

Norway, Cancer Registry of. 2022. “Cancer in Norway 2021: Cancer Incidence, Mortality, Survival and Prevalence in Norway.” 0806-3621. Cancer Registry of Norway. https://www.kreftregisteret.no/globalassets/cancer-in-norway/2021/cin_report.pdf.

R Core Team. 2020. “R: A Language and Environment for Statistical Computing.” Manual. Vienna, Austria. https://www.R-project.org/.

Welch, H. Gilbert, Benjamin L. Mazer, and Adewole S. Adamson. 2021. “The Rapid Rise in Cutaneous Melanoma Diagnoses.” New England Journal of Medicine 384 (1): 72–79. https://doi.org/gm6vs4.

Whiteman, David C., Adele C. Green, and Catherine M. Olsen. 2016. “The Growing Burden of Invasive Melanoma: Projections of Incidence Rates and Numbers of New Cases in Six Susceptible Populations Through 2031.” The Journal of Investigative Dermatology 136 (6): 1161–71. https://doi.org/f8psv4.

URL: https://therimalaya.github.io/Nordic-Melanoma