Lung Cancer Risk Calculator

How to use this lung cancer risk calculator

What this calculator does. This tool estimates the probability of a lung cancer diagnosis within 6 years and within 16 years for a person who has ever smoked cigarettes. It implements the corrected HUNT Lung Cancer Model equations, including the natural-logarithm +1 correction in the published 2022 corrigendum. The result is a population-based estimate: it does not diagnose lung cancer, predict exactly what will happen to one person, or replace a clinician's assessment. The underlying research identified age, cumulative smoking exposure, smoking intensity, time since quitting, body mass index, daily cough, and indoor smoke exposure as important predictors in the studied populations. The published HUNT model study explains the model's development and external validation.

When to use it. It can be useful for understanding how several smoking-related risk factors combine instead of looking at pack-years alone; for exploring how an otherwise identical example changes when age, quitting time, exposure, or cough history changes; for preparing a more informed conversation about lung cancer screening; and for documenting a reproducible calculation in the downloadable workbook. Screening decisions should still follow applicable clinical guidance and individual medical circumstances.

How to calculate. The calculator opens with a complete demonstration: male, age 60, 75 kg, 175 cm, 30 smoking years, 20 cigarettes per day, 5 years since quitting, 2 hours per day in smoke-filled rooms, and no daily cough. Its results and example XLSX are available immediately.

1. Replace the demonstration values with the values you want to evaluate. The calculator updates live; there is no separate Calculate button.
2. Read Risk after 6 years first, then compare it with Risk after 16 years. Use BMI and Pack-years to confirm the derived inputs are plausible.
3. Review the threshold comparisons only as historical study context. They are not a stand-alone screening recommendation.
4. Select Download Excel to export the current validated inputs and outputs into an XLSX workbook. Reset clears the demonstration and all semantic input data; the Excel button then becomes unavailable until a complete valid input set is entered again.

Input guide. Sex is required and must be Female or Male because the published equation uses a binary coefficient; the demonstration uses Male. Age is required in years and is restricted here to the published 21 – 86 model range; 60 is a valid example, and age has a strong nonlinear effect in the equation. Weight is required in kilograms and Height is required in centimeters; 75 kg and 175 cm produce a BMI of 24.49. Enter ordinary decimal numbers with a period, not a decimal comma, scientific notation, currency symbols, or unit text. Smoking years is the total time cigarettes were smoked; the demonstration uses 30 years and the value cannot exceed age. Cigarettes per day is the average daily smoking intensity and must remain from 2 through 35 for parity with the reference calculator; the demonstration uses 20. Years since quitting is required from 0 through 46; use 0 for a current smoker and, for example, 5 for someone who stopped five years ago. Hours per day in smoke-filled rooms is required from 0 through 24 and represents indoor secondhand-smoke exposure; the example uses 2. Do you cough daily during periods of the year? is required as Yes or No; the example uses No. A common mistake is to enter a lifetime pack-year total into Smoking years or Cigarettes per day. The calculator derives pack-years automatically.

Output guide. Risk after 6 years and Risk after 16 years are estimated probabilities shown as percentages; higher values mean the model assigns a higher probability over that horizon, not that cancer is present. BMI is an exact derived identity from the entered weight and height, displayed to two decimals. Pack-years is the smoking-exposure identity calculated as cigarettes per day divided by 20, multiplied by smoking years, shown to one decimal. The 6-year threshold comparison and 16-year threshold comparison state whether the model result is below or at/above 0.64% and 1.75%, respectively – the thresholds used in the original HUNT publication to form a research selection group. A result below a threshold is not “no risk,” and a result above one is not a cancer diagnosis.

Worked example. With the opening values, BMI is 75 ÷ 1.75² = 24.49 kg/m². Pack-years are (20 ÷ 20) × 30 = 30.0. The corrected 6-year equation forms its prognostic index using natural logarithms of pack-years + 1, years since quitting + 1, BMI + 1, and smoke-exposure hours + 1, then converts that index with the logistic probability formula; the displayed result is 0.98%. The corrected 16-year Cox equation uses the same underlying variables with its own coefficients and baseline survival of 0.06, producing 4.57%. Those exact current-state values are also written as numeric cells in the workbook.