O adenocarcinoma de sítio primário desconhecido (ASPD) é um subtipo histológico responsável por aproximadamente 50% a 80% de todos os casos de câncer de sítio primário desconhecido (CSPD).[4]Lee MS, Sanoff HK. Cancer of unknown primary. BMJ. 2020 Dec 7;371:m4050.
http://www.ncbi.nlm.nih.gov/pubmed/33288500?tool=bestpractice.com
[5]Pavlidis N, Pentheroudakis G. Cancer of unknown primary site. Lancet. 2012 Apr 14;379(9824):1428-35.
http://www.ncbi.nlm.nih.gov/pubmed/22414598?tool=bestpractice.com
[6]Hemminki K, Bevier M, Hemminki A, et al. Survival in cancer of unknown primary site: population-based analysis by site and histology. Ann Oncol. 2012 Jul;23(7):1854-63.
https://www.annalsofoncology.org/article/S0923-7534(19)37996-7/fulltext
http://www.ncbi.nlm.nih.gov/pubmed/22115926?tool=bestpractice.com
[7]Varadhachary GR, Raber MN. Cancer of unknown primary site. N Engl J Med. 2014 Aug 21;371(8):757-65.
http://www.ncbi.nlm.nih.gov/pubmed/25140961?tool=bestpractice.com
De acordo com a American Cancer Society, aproximadamente 32,950 novos casos de CSPD serão diagnosticados nos EUA em 2023, representando cerca de 2% de todos os novos casos de câncer.[8]American Cancer Society. Key statistics for cancers of unknown primary. 2023 [internet publication].
https://www.cancer.org/cancer/cancer-unknown-primary/about/key-statistics.html
A incidência aumenta com a idade.[9]Ganesh B, Buragamadagu B, Baralo B, et al. Cancer of unknown primary site: a population-based analysis of demographics and all-cause mortality. Paper presented at: 2022 American Society of Clinical Oncology annual meeting. Jun 3-7, 2022. Chicago, IL. Health services research and quality improvement: abstract e18518. J Clin Oncol. 2022 Jun;40(16_suppl):e18518.
https://ascopubs.org/doi/abs/10.1200/JCO.2022.40.16_suppl.e18518
[10]Cancer Research UK. Cancer of unknown primary incidence statistics: cancer of unknown primary incidence by age. 2021 [internet publication].
https://www.cancerresearchuk.org/health-professional/cancer-statistics/statistics-by-cancer-type/cancer-of-unknown-primary/incidence#heading-One
No Reino Unido, entre 2016 e 2018, aproximadamente 60% dos novos casos foram diagnosticados em indivíduos com 75 anos ou mais.[10]Cancer Research UK. Cancer of unknown primary incidence statistics: cancer of unknown primary incidence by age. 2021 [internet publication].
https://www.cancerresearchuk.org/health-professional/cancer-statistics/statistics-by-cancer-type/cancer-of-unknown-primary/incidence#heading-One
Em um estudo de coorte baseado na população dos EUA, realizado com pacientes com CSPD diagnosticado entre 2010 e 2014, a idade média no momento do diagnóstico foi de 71 anos.[9]Ganesh B, Buragamadagu B, Baralo B, et al. Cancer of unknown primary site: a population-based analysis of demographics and all-cause mortality. Paper presented at: 2022 American Society of Clinical Oncology annual meeting. Jun 3-7, 2022. Chicago, IL. Health services research and quality improvement: abstract e18518. J Clin Oncol. 2022 Jun;40(16_suppl):e18518.
https://ascopubs.org/doi/abs/10.1200/JCO.2022.40.16_suppl.e18518
No coorte realizado nos EUA com 13,441 pacientes (dos quais 9683 tinham adenocarcinoma), a maioria era branca (81.6%). O restante era formado por pacientes negros (10.8%); indígenas norte-americanos, nativos do Alaska, asiáticos/habitantes das ilhas do Pacífico (6.7%); e de raça desconhecida (0.9%).[9]Ganesh B, Buragamadagu B, Baralo B, et al. Cancer of unknown primary site: a population-based analysis of demographics and all-cause mortality. Paper presented at: 2022 American Society of Clinical Oncology annual meeting. Jun 3-7, 2022. Chicago, IL. Health services research and quality improvement: abstract e18518. J Clin Oncol. 2022 Jun;40(16_suppl):e18518.
https://ascopubs.org/doi/abs/10.1200/JCO.2022.40.16_suppl.e18518
Análises iniciais nos EUA relataram maior proporção de CSPD entre pacientes do sexo feminino ou negros, ou que viviam em situação de pobreza.[11]Urban D, Rao A, Bressel M, et al. Cancer of unknown primary: a population-based analysis of temporal change and socioeconomic disparities. Br J Cancer. 2013 Sep 3;109(5):1318-24.
https://www.nature.com/articles/bjc2013386
http://www.ncbi.nlm.nih.gov/pubmed/23860528?tool=bestpractice.com
Dados do Reino Unido indicam que as taxas de incidência de CSPD são menores entre mulheres que entre homens.[10]Cancer Research UK. Cancer of unknown primary incidence statistics: cancer of unknown primary incidence by age. 2021 [internet publication].
https://www.cancerresearchuk.org/health-professional/cancer-statistics/statistics-by-cancer-type/cancer-of-unknown-primary/incidence#heading-One
Uma taxa de incidência anual padronizada por idade de CSPD de 14 por 100,000 indivíduos (2016-2018) foi relatada no Reino Unido.[12]Cancer Research UK. Cancer of unknown primary incidence statistics: cancer of unknown primary incidence by sex and UK country. 2021 [internet publication].
https://www.cancerresearchuk.org/health-professional/cancer-statistics/statistics-by-cancer-type/cancer-of-unknown-primary/incidence#heading-Zero
Em geral, os dados epidemiológicos relacionados ao CSPD são consistentes no mundo todo, provavelmente refletindo a falta de fatores de risco definidos, genéticos ou ambientais, observados até agora nesta entidade.