Estimate a woman's 5-year and lifetime risk of developing breast cancer.
Enter 0 if pre-menopausal or not applicable.
Enter 0 if no full-term births.
No
Yes
No
Yes
Your Estimated Breast Cancer Risk:
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Understanding the Tyrer-Cuzick Breast Cancer Risk Assessment
The Tyrer-Cuzick model, also known as the International Breast Cancer Intervention Study (IBIS) model, is a widely used tool for estimating a woman's absolute risk of developing invasive breast cancer. It is based on a complex statistical algorithm that considers various risk factors to provide a personalized risk assessment. This calculator aims to provide a simplified estimation based on the key inputs of the model.
How the Calculator Works (Simplified Explanation)
The Tyrer-Cuzick model assigns a relative weight to different risk factors. These factors are combined using a logit transformation and regression coefficients derived from large population studies. The calculator takes your input for each factor and applies a simplified representation of this process.
The model estimates:
5-year absolute risk: The probability of developing breast cancer in the next five years.
Lifetime absolute risk: The probability of developing breast cancer over a woman's lifetime (typically up to age 90).
Key Risk Factors Used:
Age: Risk increases significantly with age.
Reproductive History: Early menarche, late menopause, having fewer or no children, and having the first child later in life are associated with increased risk.
Family History: Having close relatives (mother, sister, daughter) with breast cancer significantly elevates risk. The number and type of relatives are considered.
Personal History: Prior breast biopsies, especially those showing atypical hyperplasia, and a history of chest radiation therapy (particularly at a young age) are strong risk factors.
Interpreting the Results:
The output of this calculator is an estimated risk percentage. It is crucial to understand that this is a statistical estimate and not a definitive prediction. The actual risk for any individual may vary. This tool is intended for informational purposes and should be discussed with a healthcare professional. They can provide a more comprehensive assessment and discuss appropriate screening or risk-reduction strategies based on your individual circumstances and the full Tyrer-Cuzick model.
Important Disclaimer:
This online calculator provides an approximation based on simplified calculations derived from the Tyrer-Cuzick model. It is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website.
function calculateRisk() {
var age = parseFloat(document.getElementById("age").value);
var menarcheAge = parseFloat(document.getElementById("menarcheAge").value);
var menopauseAge = parseFloat(document.getElementById("menopauseAge").value);
var births = parseFloat(document.getElementById("births").value);
var ageAtFirstBirth = parseFloat(document.getElementById("ageAtFirstBirth").value);
var familyHistory = parseFloat(document.getElementById("familyHistory").value);
var biopsies = parseFloat(document.getElementById("biopsies").value);
var atypia = parseFloat(document.getElementById("atypia").value);
var radiationTherapy = parseFloat(document.getElementById("radiationTherapy").value);
var resultElement = document.getElementById("result");
var riskOutputElement = document.getElementById("riskOutput");
var explanationElement = document.getElementById("explanation");
// Basic validation
if (isNaN(age) || age 120 ||
isNaN(menarcheAge) || menarcheAge 18 ||
isNaN(menopauseAge) || menopauseAge 70 ||
isNaN(births) || births < 0 ||
isNaN(ageAtFirstBirth) || ageAtFirstBirth 55 ||
isNaN(familyHistory) || familyHistory < 0 ||
isNaN(biopsies) || biopsies < 0 ||
isNaN(atypia) || (atypia !== 0 && atypia !== 1) ||
isNaN(radiationTherapy) || (radiationTherapy !== 0 && radiationTherapy !== 1)) {
riskOutputElement.textContent = "Invalid Input";
riskOutputElement.style.color = "red";
explanationElement.textContent = "Please ensure all inputs are valid numbers and within the expected ranges.";
return;
}
// — Simplified Tyrer-Cuzick Logic —
// This is a highly simplified approximation for demonstration purposes.
// The actual Tyrer-Cuzick model uses complex regression coefficients and is
// implemented in specialized software.
// The following calculation assigns arbitrary points based on risk factors.
var riskScore = 0;
// Age component (simplified linear increase for demonstration)
riskScore += age * 0.04;
// Reproductive factors
if (menarcheAge 14) riskScore += 0.5;
var isMenopausal = menopauseAge > 0 && menopauseAge 50) riskScore += 0.5;
} else { // Pre-menopausal or perimenopausal
riskScore += 1; // Increased risk if still menstruating at older age
}
if (births === 0) riskScore += 1;
if (births >= 1 && ageAtFirstBirth > 30) riskScore += 1;
if (births >= 1 && ageAtFirstBirth < 20) riskScore -= 0.5;
// Family History
riskScore += familyHistory * 1.5; // Increased weight for family history
// Personal History
riskScore += biopsies * 0.5;
if (atypia === 1) riskScore += 2; // Higher weight for atypical hyperplasia
if (radiationTherapy === 1) riskScore += 1.5;
// — Convert score to approximate 5-year and lifetime risk —
// These are VERY rough estimations. The actual model uses complex transformations.
var estimated5YearRisk = (riskScore / 10) * 1.5; // Arbitrary scaling
var estimatedLifetimeRisk = (riskScore / 5) * 2.0; // Arbitrary scaling
// Cap risks at reasonable maximums
estimated5YearRisk = Math.min(estimated5YearRisk, 15); // Max 15% for 5-year risk
estimatedLifetimeRisk = Math.min(estimatedLifetimeRisk, 80); // Max 80% for lifetime risk
// Format output
var formatted5YearRisk = estimated5YearRisk.toFixed(2);
var formattedLifetimeRisk = estimatedLifetimeRisk.toFixed(2);
riskOutputElement.textContent = "5-Year: " + formatted5YearRisk + "% | Lifetime: " + formattedLifetimeRisk + "%";
riskOutputElement.style.color = "#28a745"; // Success green
explanationElement.innerHTML = `
Based on your inputs, your estimated 5-year risk is ${formatted5YearRisk}% and your lifetime risk is ${formattedLifetimeRisk}%.
Note: This is a simplified estimation. The full Tyrer-Cuzick model involves more complex calculations and is best interpreted by a healthcare professional.
`;
}