Hairy cell leukaemia (HCL) is uncommon. The incidence rate in the US has been estimated to be 0.3 per 100,000 (2011-2012 data; age adjusted to the US standard population).[3]Teras LR, DeSantis CE, Cerhan JR, et al. 2016 US lymphoid malignancy statistics by World Health Organization subtypes. CA Cancer J Clin. 2016 Nov 12;66(6):443-59.
https://www.doi.org/10.3322/caac.21357
http://www.ncbi.nlm.nih.gov/pubmed/27618563?tool=bestpractice.com
There were an estimated 1100 new cases of HCL in the US in 2016.[3]Teras LR, DeSantis CE, Cerhan JR, et al. 2016 US lymphoid malignancy statistics by World Health Organization subtypes. CA Cancer J Clin. 2016 Nov 12;66(6):443-59.
https://www.doi.org/10.3322/caac.21357
http://www.ncbi.nlm.nih.gov/pubmed/27618563?tool=bestpractice.com
In the US, incidence of HCL is highest among non-Hispanic white people (0.5 per 100,000, age adjusted to the US standard population), followed by non-Hispanic black people (0.3 per 100,000), Hispanic people (0.3 per 100,000), and Asian/Pacific Islanders (0.2 per 100,000).[3]Teras LR, DeSantis CE, Cerhan JR, et al. 2016 US lymphoid malignancy statistics by World Health Organization subtypes. CA Cancer J Clin. 2016 Nov 12;66(6):443-59.
https://www.doi.org/10.3322/caac.21357
http://www.ncbi.nlm.nih.gov/pubmed/27618563?tool=bestpractice.com
The incidence of HCL in the UK is estimated to be 0.34 per 100,000 per year (2005-2019 data).[4]Lamb M, Painter D, Howell D, et al. Lymphoid blood cancers, incidence and survival 2005-2023: a report from the UK's Haematological Malignancy Research Network. Cancer Epidemiol. 2024 Feb;88:102513.
https://www.sciencedirect.com/science/article/pii/S1877782123001935?via%3Dihub
http://www.ncbi.nlm.nih.gov/pubmed/38160571?tool=bestpractice.com
Median age at diagnosis has variously been reported as 55-67 years.[4]Lamb M, Painter D, Howell D, et al. Lymphoid blood cancers, incidence and survival 2005-2023: a report from the UK's Haematological Malignancy Research Network. Cancer Epidemiol. 2024 Feb;88:102513.
https://www.sciencedirect.com/science/article/pii/S1877782123001935?via%3Dihub
http://www.ncbi.nlm.nih.gov/pubmed/38160571?tool=bestpractice.com
[5]Monnereau A, Slager SL, Hughes AM, et al. Medical history, lifestyle, and occupational risk factors for hairy cell leukemia: the InterLymph Non-Hodgkin Lymphoma Subtypes Project. J Natl Cancer Inst Monogr. 2014 Aug;2014(48):115-24.
https://www.doi.org/10.1093/jncimonographs/lgu004
http://www.ncbi.nlm.nih.gov/pubmed/25174032?tool=bestpractice.com
[6]Paillassa J, Cornet E, Noel S, et al. Analysis of a cohort of 279 patients with hairy-cell leukemia (HCL): 10 years of follow-up. Blood Cancer J. 2020 May 27;10(5):62.
https://www.doi.org/10.1038/s41408-020-0328-z
http://www.ncbi.nlm.nih.gov/pubmed/32461544?tool=bestpractice.com
[7]Parry-Jones N, Joshi A, Forconi F, et al. Guideline for diagnosis and management of hairy cell leukaemia (HCL) and hairy cell variant (HCL-V). Br J Haematol. 2020 Dec;191(5):730-7.
https://www.doi.org/10.1111/bjh.17055
http://www.ncbi.nlm.nih.gov/pubmed/33053222?tool=bestpractice.com
[8]Wiber M, Maitre E, Poncet JM, et al. A population-based study of hairy cell leukemia over a period of 20 years. Cancer Treat Res Commun. 2020;25:100236.
https://www.sciencedirect.com/science/article/pii/S246829422030071X?via%3Dihub
http://www.ncbi.nlm.nih.gov/pubmed/33227559?tool=bestpractice.com
HCL is more common in males (male:female incidence rate ratio of 2.77 [2011-2012 US data]).[3]Teras LR, DeSantis CE, Cerhan JR, et al. 2016 US lymphoid malignancy statistics by World Health Organization subtypes. CA Cancer J Clin. 2016 Nov 12;66(6):443-59.
https://www.doi.org/10.3322/caac.21357
http://www.ncbi.nlm.nih.gov/pubmed/27618563?tool=bestpractice.com
Occupational exposures (e.g., farming, industrial, engineering) may contribute to sex differences.[5]Monnereau A, Slager SL, Hughes AM, et al. Medical history, lifestyle, and occupational risk factors for hairy cell leukemia: the InterLymph Non-Hodgkin Lymphoma Subtypes Project. J Natl Cancer Inst Monogr. 2014 Aug;2014(48):115-24.
https://www.doi.org/10.1093/jncimonographs/lgu004
http://www.ncbi.nlm.nih.gov/pubmed/25174032?tool=bestpractice.com
[9]Staines A, Cartwright RA. Hairy cell leukaemia: descriptive epidemiology and a case-control study. Br J Haematol. 1993 Dec;85(4):714-7.
http://www.ncbi.nlm.nih.gov/pubmed/7918034?tool=bestpractice.com
[10]Tadmor T, Polliack A. Epidemiology and environmental risk in hairy cell leukemia. Best Pract Res Clin Haematol. 2015 Dec;28(4):175-9.
http://www.ncbi.nlm.nih.gov/pubmed/26614895?tool=bestpractice.com
[11]Nordström M, Hardell L, Magnuson A, et al. Occupational exposures, animal exposure and smoking as risk factors for hairy cell leukaemia evaluated in a case-control study. Br J Cancer. 1998 Jun;77(11):2048-52.
http://www.ncbi.nlm.nih.gov/pubmed/9667691?tool=bestpractice.com
[12]Orsi L, Delabre L, Monnereau A, et al. Occupational exposure to pesticides and lymphoid neoplasms among men: results of a French case-control study. Occup Environ Med. 2009 May;66(5):291-8.
http://www.ncbi.nlm.nih.gov/pubmed/19017688?tool=bestpractice.com
HCL appears to occur more commonly in the western hemisphere (e.g., US, UK) than other regions (e.g., Japan, Africa), although accurate epidemiological data for other regions are lacking.[13]Itamura H, Ide M, Sato A, et al. Identification of the BRAF V600E mutation in Japanese patients with hairy cell leukemia and related diseases using a quenching probe method. Int J Hematol. 2018 Oct;108(4):416-22.
http://www.ncbi.nlm.nih.gov/pubmed/30043333?tool=bestpractice.com
[14]Gini Ehungu JL, Mufuta JP, Ngiyulu RM, et al. A rare occurrence of hairy cell leukemia in a congolese child: a presentation and challenge of diagnosis in low resource settings. J Pediatr Hematol Oncol. 2013 Nov;35(8):e350-2.
http://www.ncbi.nlm.nih.gov/pubmed/23652869?tool=bestpractice.com