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Calcimator

Neutropenia Risk Score Calculator

Assess febrile neutropenia risk from regimen myelotoxicity, patient factors, and ANC. Determines G-CSF prophylaxis recommendation per NCCN/ASCO guidelines.

About this calculator

This calculator does two distinct jobs: it computes the Absolute Neutrophil Count (ANC) directly from a CBC differential, and separately estimates febrile neutropenia (FN) risk using a simplified version of the NCCN/ASCO risk framework. ANC is calculated as white blood cell count times the combined percentage of segmented neutrophils and bands, divided by 100 -- a standard formula that depends only on those three CBC values and nothing else the calculator collects, so patient age and the chemotherapy regimen's risk class have no effect on the ANC number itself, only on the separate FN risk estimate. That ANC feeds CTCAE neutropenia grading (grade 1 at 1.5-2.0 x10^3/uL down to grade 4 below 0.5), which is a lab-based severity classification distinct from FN risk prediction.

FN risk starts from the regimen's published myelotoxicity class -- roughly 25% baseline for high-risk regimens, 15% for intermediate, 5% for low -- and then layers on points for patient-level risk factors: age 65 or older, prior chemotherapy or radiation, bone marrow tumor involvement, renal or hepatic dysfunction, active infection, and an ANC already under 1.5. NCCN guidance generally recommends prophylactic G-CSF when total FN risk reaches 20% or higher, which this calculator applies as its recommendation threshold. This is a simplified educational model, not the full NCCN/ASCO decision algorithm -- it does not incorporate every patient comorbidity or regimen-specific evidence a real risk assessment considers, and prophylaxis decisions should follow the current published NCCN guideline directly.

Inputs

%
%

Results

ANC (×10³/μL)

3.1

Total FN risk (%)

15

Neutropenia grade (CTCAE)0
Regimen base FN risk (%)15
Risk category (1=low, 2=mid, 3=high)2
G-CSF recommended (0/1)0
How to Use This Calculator
  1. Enter WBC, neutrophil percentage, and band percentage from the CBC differential to calculate ANC.
  2. Enter patient age and regimen risk class (1=low, 2=intermediate, 3=high myelotoxicity).
  3. Enter prior chemo/radiation, bone marrow involvement, renal/hepatic dysfunction, and active infection status.
  4. Read the ANC, CTCAE neutropenia grade, regimen base FN risk, and total FN risk with risk category (low, intermediate, high).
  5. Review the G-CSF prophylaxis recommendation, triggered when total FN risk is ≥20% per NCCN/ASCO guidelines.

How the result changes with WBC (×10³/μL)

WBC (×10³/μL)ANC (×10³/μL)Total FN risk (%)
2.51.5515
3.752.3315
7.54.6515
138.0615

What each input means

WBC (×10³/μL)
White blood cell count from CBC.
Neutrophils (%)
Segmented neutrophils percentage on differential.
Bands (%)
Band neutrophils percentage on differential.
Patient age (years)
Patients ≥65 have increased FN risk.
Regimen risk
Myelotoxicity class of the chemotherapy regimen.
Prior chemo/radiation
Previous chemotherapy or radiation therapy.
Bone marrow involvement
Tumor involvement of bone marrow.
Renal/hepatic dysfunction
Significant renal or hepatic impairment.
Active infection
Open wounds or active infection at treatment start.

What each result means

ANC (×10³/μL)
Absolute neutrophil count = WBC × (neutrophils% + bands%) / 100.
Neutropenia grade (CTCAE)
Grade 0=normal, 1 (ANC ~1.8 LLN–1.5), 2 (1.0–1.5), 3 (0.5–1.0), 4 (<0.5). CTCAE defines grade 1 relative to institutional LLN, approximated here as 1.8.
Regimen base FN risk (%)
Baseline febrile neutropenia risk from regimen alone.
Total FN risk (%)
Combined risk from regimen + patient factors.
Risk category (1=low, 2=mid, 3=high)
1 = <10%, 2 = 10–19.9%, 3 = ≥20% (matches the G-CSF prophylaxis threshold).
G-CSF recommended (0/1)
Prophylactic G-CSF recommended when FN risk ≥ 20% per NCCN guidelines.

How this is calculated

Worked example, using the default values

  1. Identify Input Parameters
    9 parameters
    WBC (×10³/μL) = 5, Neutrophils (%) = 60, Bands (%) = 2, Patient age (years) = 55, Regimen risk = 2, Prior chemo/radiation = 0, Bone marrow involvement = 0, Renal/hepatic dysfunction = 0, Active infection = 0 = 9 input(s) provided
  2. Calculate ANC
    ANC = wbc * (neutrophilPct + bandPct) / 100
    3.1 = 3.1
  3. Calculate Total FN risk
    Total FN risk = min(95, baseFNRiskPct + additionalRiskPct)
    15 = 15
  4. Calculate Neutropenia grade
    Neutropenia grade
    0 = 0
  5. Calculate Regimen base FN risk
    Regimen base FN risk
    15 = 15

Engine last updated . Checked against 2 independently-derived tests — how we verify calculators. Built by Paul Gunder, a software engineer, not a licensed financial, medical, or legal professional.

Frequently Asked Questions

Why doesn't patient age affect the calculated ANC?

ANC is a direct lab calculation -- white blood cell count multiplied by the combined neutrophil and band percentage -- that has nothing to do with the patient's age. Age only enters this calculator's second calculation, the febrile neutropenia risk estimate, where patients 65 and older receive additional risk points separate from whatever their ANC happens to be.

How is CTCAE neutropenia grade different from febrile neutropenia risk?

Neutropenia grade is a snapshot lab classification of how low the current ANC is right now, from grade 1 (mildly low) to grade 4 (severely low, under 0.5 x10^3/uL). Febrile neutropenia risk is a forward-looking estimate of the probability of developing a fever with neutropenia over an upcoming chemotherapy cycle, which factors in the current ANC alongside the regimen's myelotoxicity and other patient risk factors -- a patient with a currently normal ANC can still carry meaningful FN risk from a highly myelotoxic upcoming regimen.

What does the G-CSF recommendation threshold actually mean?

This calculator flags prophylactic G-CSF (a growth factor that stimulates neutrophil production) as recommended once total estimated FN risk reaches 20% or higher, mirroring the general NCCN threshold for primary prophylaxis -- and the Risk category output uses that same 20% cutoff for its high-risk tier, so the two outputs never disagree at exactly 20%. Risk from 10% up to (but not including) 20% is considered intermediate, where the guideline typically calls for weighing additional patient-specific risk factors rather than applying prophylaxis automatically.

Are the specific point values (+5 for age, +6 for bone marrow involvement, etc.) from a published NCCN/ASCO table?

No -- NCCN/ASCO guidance stratifies regimens into risk tiers (high ≥20%, intermediate 10-20%, low <10%) and then calls for a qualitative assessment of patient-specific risk factors, not a published points table. The specific additive point values this calculator uses for age, prior treatment, bone marrow involvement, organ dysfunction, active infection, and low ANC are this tool's own simplified scoring choices, designed to roughly reflect that bone marrow involvement and active infection represent a more direct, mechanism-specific threat to neutrophil recovery than a general risk marker like age -- but the exact numbers are illustrative, not derived from a cited source.

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