The white cell count at diagnosis in infants, and why the reported medians disagree by fivefold
also called WBC at diagnosis infant ALL · hyperleukocytosis frequency infant · leucocyte count infant leukaemia · initial WBC
Babies with leukaemia arrive with far more white cells in their blood than older children do, but how many arrive with an extreme count depends heavily on which country's study you read: 29-30% in the European and Japanese trials against 11% in the Chinese one. A large part of that gap is who got enrolled, not how the disease behaves.
The same thing, for a scientist
White cell count at diagnosis is the one presenting feature that infant trials report consistently, because it is a stratification variable rather than a physical sign. The proportion with WBC >=300 x10^9/L was 29% in Interfant-06 and 30% in JPLSG MLL-10 as reported in the CCCG-ALL-2015 comparison, against 11.2% in CCCG-ALL-2015 itself, whose authors attribute the gap to under-representation of high-risk infants in their enrolment rather than to biology [E1]. CCCG's median was 62.7 x10^9/L (range 1.3-777) [E1]. Older infant series give means rather than medians: the TCCSG cohort reports a mean of 205,900/microlitre with an SEM of 35,700, a statistic that is close to uninterpretable on a distribution this skewed [E2]. Interfant-06 found WBC to be an independent prognostic factor for event-free survival, ranking behind KMT2A rearrangement and age [E3], and Interfant-99 found 'very high white blood cell count' independently associated with inferior outcome [E4].
The numbers, and who they came from1 deeper
| Cohort | n (infants) | Median WBC x10^9/L | Proportion >=300 x10^9/L |
|---|---|---|---|
| Interfant-06 | 651 | not in the abstract | 29% as reported in 1 |
| JPLSG MLL-10 | 90 | not in the abstract | 30% as reported in 1 |
| CCCG-ALL-2015 infants | 134 | 62.7 (range 1.3-777) | 11.2% 1 |
| TCCSG infant ALL 1977-1995 | 62 | mean 205,900/microlitre (SEM 35,700), median not given | not stated 2 |
| Single US hospital, infants <6 months | 9 | range 42,000-1,600,000/microlitre | not stated 5 |
The CCCG authors are explicit that their cohort is unrepresentative: infants were 1.7% of their whole 7,640-patient ALL protocol against an expected 3-4%; only 18.4% were under six months against 50-68% reported elsewhere; and KMT2A rearrangement was present in 53.0% against 74-83% elsewhere 1. A cohort that under-enrols the youngest and the KMT2A-rearranged will under-report hyperleukocytosis for structural reasons.
A mean is the wrong statistic here
The TCCSG report gives a mean of 205,900/microlitre 2. The CCCG distribution runs from 1.3 to 777 x10^9/L with a median of 62.7 1 - a ratio of median to maximum of roughly 1:12, which is a long right tail. On that shape the mean sits well above the typical patient and moves with a handful of extreme cases, so a mean of 205,900 tells you that the cohort contained some very high counts and almost nothing about the infant in front of you. Where a paper reports only a mean for this variable, treat it as a statement about the tail.
What follows clinically
A count in the hundreds of thousands in a 4 kg infant is a different problem from the same count in a 40 kg child, because the circulating blood volume is roughly a tenth and the vascular access for cytoreduction is correspondingly harder - see concept-hyperleukocytosis-cytoreduction-in-a-neonate. The count also drives stratification: Interfant-06 used WBC >=300 x10^9/L or a poor prednisone response together with age <6 months as the high-risk definition [E-interfant06-age-direction] (this entry previously said >6 months, which was backwards - see the correction section), and the arbitrariness of that line is dealt with in concept-wbc-300-threshold-is-an-administrative-choice.
Correction: Interfant-06 high risk is age UNDER six months
Correction, 2026-09-20: the age criterion was recorded backwards, and it is UNDER six months. Two sources were fetched and read directly.
ClinicalTrials.gov NCT00550992, raw API, states the three groups explicitly, and the medium-risk line settles it on its own:
Medium-risk disease, defined by 1 of the following criteria: MLL status unknown; MLL rearranged AND age > 6 months; MLL rearranged AND age < 6 months AND WBC < 300 x 10^9/L AND prednisone good response
High-risk disease, defined by MLL rearrangement AND meets the following criteria: Age at diagnosis < 6 months (i.e., < 183 days); WBC >= 300 x 10^9/L AND/OR prednisone poor response
PMID 33405950, from the Interfant group itself, read in full text (PMC8196086 via efetch db=pmc, 22,863 characters after stripping): "Other high-risk factors on the Interfant-06 treatment protocol include age < 6 months at diagnosis and a high WBC count at diagnosis (>= 300 x 10^9/L) and/or a poor prednisone response."
Two further consequences.
First, the criterion is a conjunction, not a list. High risk requires KMT2A rearrangement and age under six months and (WBC >= 300 or poor prednisone response). An eight-month-old with a WBC of 400 is medium risk under this protocol, which the previous wording got wrong in the other direction too.
Second, the anomaly this graph recorded was never real. The entry asked why age appeared with opposite sign in Interfant-99 and Interfant-06 and left it open as a question about trial design. Both protocols treat the youngest infants as the highest risk and always did. The sign flip was ours. The JCO abstract is what both entries quoted, so this is a transcription or abstract-reading error and not an invention - but it stood through a beat that noticed it, flagged it, and then explained it rather than checking it, which is the more instructive part.
| metric | white cell count at diagnosis |
|---|---|
| unit | x10^9/L |
| population | infants <1 year with ALL |
cohorts — the numbers behind the chart
[
{
"cohort": "CCCG-ALL-2015",
"n": 134,
"median": 62.7,
"range": [
1.3,
777
],
"pct_ge_300": 11.2,
"pmid": "38634141",
"title": "Outcome of infants with acute lymphoblastic leukemia treated with the Chinese Children's Cancer Group Acute Lymphoblastic Leukemia 2015 study protocol.",
"authors": "Leung AWK, Cai J, Wan Z, et al.",
"venue": "Haematologica",
"year": 2024,
"title_provenance": "Title/authors/venue backfilled from PubMed esummary on 2026-09-20 because this citation stored a bare PMID with no title, which made it unscoreable by verify-citations.py. BACKFILLING IS NOT VERIFICATION: it confirms the PMID resolves to a real paper, not that this is the right paper for the claim. That still requires reading."
},
{
"cohort": "Interfant-06",
"n": 651,
"pct_ge_300": 29,
"source": "as reported in PMID 38634141 discussion",
"pmid": "31283407",
"title": "Outcome of Infants Younger Than 1 Year With Acute Lymphoblastic Leukemia Treated With the Interfant-06 Protocol: Results From an International Phase III Randomized Study.",
"authors": "Pieters R, De Lorenzo P, Ancliffe P, et al.",
"venue": "J Clin Oncol",
"year": 2019,
"title_provenance": "Title/authors/venue backfilled from PubMed esummary on 2026-09-20 because this citation stored a bare PMID with no title, which made it unscoreable by verify-citations.py. BACKFILLING IS NOT VERIFICATION: it confirms the PMID resolves to a real paper, not that this is the right paper for the claim. That still requires reading."
},
{
"cohort": "JPLSG MLL-10",
"n": 90,
"pct_ge_300": 30,
"source": "as reported in PMID 38634141 discussion",
"pmid": "32845001",
"title": "A risk-stratified therapy for infants with acute lymphoblastic leukemia: a report from the JPLSG MLL-10 trial.",
"authors": "Tomizawa D, Miyamura T, Imamura T, et al.",
"venue": "Blood",
"year": 2020,
"title_provenance": "Title/authors/venue backfilled from PubMed esummary on 2026-09-20 because this citation stored a bare PMID with no title, which made it unscoreable by verify-citations.py. BACKFILLING IS NOT VERIFICATION: it confirms the PMID resolves to a real paper, not that this is the right paper for the claim. That still requires reading."
},
{
"cohort": "TCCSG 1977-1995",
"n": 62,
"mean_per_microlitre": 205900,
"sem_per_microlitre": 35700,
"pmid": "10530057",
"title": "Clinical and biological aspects of acute lymphoblastic leukemia in 62 infants: retrospective analysis of the Tokyo Children's Cancer Study Group.",
"authors": "Isoyama K, Okawa H, Hayashi Y, et al.",
"venue": "Pediatr Int",
"year": 1999,
"title_provenance": "Title/authors/venue backfilled from PubMed esummary on 2026-09-20 because this citation stored a bare PMID with no title, which made it unscoreable by verify-citations.py. BACKFILLING IS NOT VERIFICATION: it confirms the PMID resolves to a real paper, not that this is the right paper for the claim. That still requires reading."
}
]- Is the threefold gap in the proportion with WBC >=300 x10^9/L between CCCG-ALL-2015 and Interfant-06/MLL-10 wholly explained by enrolment, or is there a real population difference in presenting tumour burden?
- What is the median WBC at diagnosis in Interfant-06 and MLL-10? Neither abstract gives it and both full texts are paywalled; this beat could not obtain the single most-cited number in infant ALL.
- Would a continuous (spline) model of WBC outperform the >=300 dichotomy for risk stratification in infants?
- E1strong confidence 4 of 5: Replicated in peer-reviewed work by more than one group.paper
Among 134 infants in CCCG-ALL-2015 the median WBC was 62.7 x10^9/L (range 1.3-777) with 11.2% at or above 300 x10^9/L, which the authors contrast with 29% in Interfant-06 and 30% in JPLSG MLL-10 and attribute to under-representation of high-risk infants in their cohort.
Outcome of infants with acute lymphoblastic leukemia treated with the Chinese Children's Cancer Group Acute Lymphoblastic Leukemia 2015 study protocol. · Leung AWK, Cai J, Wan Z, Qin J, Fang Y, Sun L, et al. · Haematologica 2024What this evidence cannot show
The 29% and 30% figures are quoted in this paper's discussion from its references 3 and 8 (Interfant-06 and MLL-10), not measured here; they were read in the open-access full text at PMC11290514 and not independently confirmed against the Interfant-06 and MLL-10 papers' own tables, whose full texts are paywalled. The CCCG cohort is self-declared unrepresentative: infants were 1.7% of the parent protocol against an expected 3-4%, 18.4% were under six months against 50-68% elsewhere, and KMT2A-r was 53.0% against 74-83% elsewhere.
Evidence that argues against this (1)
- If the CCCG cohort is unrepresentative in enrolment, then so may be the comparison it draws; the proper comparator would be a registry rather than three trial cohorts with different eligibility. No such infant registry comparison was found in this beat. Stutterheim J et al. 2025
- E2moderate confidence 3 of 5: One strong study, or several smaller consistent ones.paper
In 62 infants with ALL from the Tokyo Children's Cancer Study Group the mean leucocyte count at diagnosis was 205,900 +/- 35,700 per microlitre, and hyperleukocytosis above 50,000 per microlitre was associated with poor prognosis.
Clinical and biological aspects of acute lymphoblastic leukemia in 62 infants: retrospective analysis of the Tokyo Children's Cancer Study Group. · Isoyama K, Okawa H, Hayashi Y, Hanada R, Okimoto Y, Maeda M, et al. · Pediatr Int 1999What this evidence cannot show
A mean with an SEM on a strongly right-skewed variable; no median, no interquartile range, no proportion above any threshold. Cohort spans 1977-1995 and predates modern supportive care and molecular diagnostics. The 50,000 threshold used for the prognostic claim is a third administrative cut-point, different again from 100,000 and 300,000 used elsewhere.
Evidence that argues against this (1)
- The prognostic effect of a dichotomised WBC depends on where the line is drawn, and this cohort's line (50,000) differs from Interfant's (300,000); a threshold-free analysis could show a smoother or weaker relationship. Pieters R et al. 2019
- E3established confidence 5 of 5: Multiple independent lines of evidence; treated as settled in the field.paper
In Interfant-06 (n = 651) KMT2A rearrangement was the strongest prognostic factor for event-free survival, followed by age, WBC count and prednisone response, and the high-risk group was defined as KMT2A-rearranged, older than 6 months, with WBC >=300 x10^9/L or poor prednisone response. **CORRECTED 2026-09-20: this reads 'older than 6 months' and the protocol says UNDER 6 months** - NCT00550992 raw eligibility and PMID 33405950 full text, both fetched. The criterion is also a conjunction: KMT2A-r AND age < 6 months AND (WBC >= 300 OR poor prednisone response).
Outcome of Infants Younger Than 1 Year With Acute Lymphoblastic Leukemia Treated With the Interfant-06 Protocol: Results From an International Phase III Randomized Study. · Pieters R, De Lorenzo P, Ancliffe P, Aversa LA, Brethon B, Biondi A, et al. · J Clin Oncol 2019What this evidence cannot show
Abstract read; the full text and its baseline characteristics table are paywalled and were not retrieved, so the median WBC for this cohort is not carried here. The ordering of prognostic factors comes from a multivariable model whose covariate list is not in the abstract.
Evidence that argues against this (1)
- The same trial's conclusion is that outcome did not improve over Interfant-99, so a stratification built on these factors has not yet translated into benefit. Pieters R et al. 2007
- E4established confidence 5 of 5: Multiple independent lines of evidence; treated as settled in the field.paper
In Interfant-99 (n = 482) all types of MLL/KMT2A rearrangement, very high white blood cell count, age younger than 6 months and poor prednisone response were independently associated with inferior outcome.
A treatment protocol for infants younger than 1 year with acute lymphoblastic leukaemia (Interfant-99): an observational study and a multicentre randomised trial. · Pieters R, Schrappe M, De Lorenzo P, Hann I, De Rossi G, Felice M, et al. · Lancet 2007What this evidence cannot show
Abstract read; full text paywalled. 'Very high white blood cell count' is not given a numerical threshold in the abstract. 4-year EFS 47.0% (SE 2.6, 95% CI 41.9-52.1).
Evidence that argues against this (1)
- Interfant-06 with a larger cohort produced a 6-year EFS of 46.1%, essentially unchanged, so the prognostic factors identified in 1999-2005 did not yield an improvement when acted on. Pieters R et al. 2019
- E5weak confidence 2 of 5: Preliminary, small, indirect, or not yet peer reviewed.paper
In nine infants under 6 months with ALL at one US hospital the white cell count at diagnosis ranged from 42,000 to 1.6 million per microlitre.
Infant acute lymphoblastic leukemia: a 20-year children's hospital experience. · Murray RA, Thom G, Gardner RV, Craver RD · Fetal Pediatr Pathol 2008What this evidence cannot show
n = 9, retrospective, range only, no central tendency reported.
Evidence that argues against this (1)
- A range from nine patients cannot establish a distribution and is shown here only to indicate the upper extreme that occurs in this age group. Leung AWK et al. 2024
- E-interfant06-age-directionestablished confidence 5 of 5: Multiple independent lines of evidence; treated as settled in the field.registry
Interfant-06 defines high risk as KMT2A rearrangement AND age at diagnosis under 6 months (under 183 days) AND either WBC at least 300 x10^9/L or a poor prednisone response. KMT2A-rearranged infants older than 6 months are explicitly medium risk, as are KMT2A-rearranged infants under 6 months with WBC below 300 and a good prednisone response.
Interfant-06: International Collaborative Treatment Protocol for Infants Under One Year With Acute Lymphoblastic or Biphenotypic Leukemia - registered eligibility and risk-group definitions · ClinicalTrials.gov 2026What this evidence cannot show
Fetched from the ClinicalTrials.gov v2 API on 2026-09-20 and read verbatim, and independently confirmed in the full text of PMID 33405950, which is written by the Interfant group. Established as a fact about the protocol's stated definition. **The registry is not the protocol document**, and the Interfant-06 primary report (PMID 31283407) could not be opened - no PMCID and the publisher returns HTTP 403 - so the possibility that the published abstract's wording reflects a real amendment rather than an error is not formally excluded. Against that: the registry, the group's own 2021 full text and an independent full text (PMID 36861410) all agree on under 6 months.
Evidence that argues against this (1)
- The abstract of the Interfant-06 primary report is the source both entries quoted, and it is what produced the reversal - so a reader going back to the most authoritative-looking source for this protocol may find the wrong direction there too. That is the reason this correction records the registry and a full text rather than simply flipping the sentence. Journal of Clinical Oncology 2021
presenting white cell count distribution in infants
- related to →Interfant-06 — 651 infants, and the definitive answer that myeloid-style consolidation does not help
WBC >=300 x10^9/L is an Interfant-06 stratification variable
supplies the infant-specific denominator for the hyperleukocytosis emergency
how often this emergency arises depends on the WBC distribution
the 300 x10^9/L line applied to a continuous distribution
- ← related toHypothesis: the spread in infant presenting-feature frequencies is mostly measurement, not biology
the WBC spread is selection rather than measurement, and tests the hypothesis's scope
the arbitrariness of the 300 line, dealt with here