While the peak incidence of acute lymphoblastic leukemia in the general pediatric population typically occurs between ages 2 and 5, children with Down syndrome exhibit a significantly higher risk for developing ALL at a younger age. According to cancer.gov, the presence of certain genetic conditions, such as Down syndrome, places children at very high risk for earlier onset of ALL, with the disease often manifesting before the age of 5. Additionally, Amboss notes that the risk of ALL in Down syndrome patients is 10-20 times higher compared to the general population. This heightened risk for earlier onset is also emphasized in UpToDate, which reports that ALL occurs more frequently in children with Down syndrome, contributing to 1-3% of all ALL cases.
Interestingly, First Aid 2023 does not specify the age of onset for ALL in Down syndrome patients but highlights the general association between Down syndrome and a higher incidence of ALL. Given the increased risk in this population, it would be reasonable to infer that the age of onset for ALL in Down syndrome patients is likely to be at a younger age rather than an ‘ALLder’ age, considering the overall trend in the general population where peak incidence occurs in children aged 2-5 years.
Sources:
1. https://www.cancer.gov/types/leukemia/patient/child-all-treatment-pdq#_20
2. Ostermaier KK. Down Syndrome: Clinical Features and Diagnosis. In: Post TW, ed. UpToDate. Waltham, MA: UpToDate. https://www.uptodate.com/contents/down-syndrome-clinical-features-and-diagnosis. Last updated November 22, 2015. Accessed April 12, 2017.
UpToDate Quote: "UpToDate Quote: "Acute lymphoblastic leukemia — The risk of developing ALL is approximately 10 to 20 times higher in DS compared with children without DS [36,94-96] and accounts for 1 to 3 percent of all patients with ALL. The clinical presentation is similar to that in children without DS. (See "Overview of the clinical presentation and diagnosis of acute lymphoblastic leukemia/lymphoma in children".)"
3. Amboss Article: “Acute Leukemia”; Epidemiology; Etiology
4. First Aid 2023, pg 437
I have looked in lecture notes and external resources, and cannot find any evidence to support that ALL occurs "ALLder" than 5 years old in Down syndrome patients.
If there is something I am missing, I would appreciate being corrected so I can learn if I am mistaken.