This calculator provides an estimated risk of developing breast cancer based on common risk factors.
It is for informational purposes only and not a substitute for professional medical advice.
Your Estimated 5-Year Risk:
—
This is a simplified estimation. For accurate assessment, consult a healthcare professional.
Understanding Breast Cancer Risk Factors and Assessment
Breast cancer is a complex disease, and its risk is influenced by a combination of genetic, environmental, and lifestyle factors. Understanding these factors can empower individuals to make informed decisions about their health and screening. This calculator aims to provide a basic estimation of an individual's risk over a 5-year period, based on commonly recognized contributing factors.
Key Risk Factors Included:
Age: The risk of breast cancer increases with age, particularly after 50.
Family History: A history of breast cancer in first-degree relatives (mother, sister, daughter) significantly increases risk. Certain genetic mutations, like BRCA1 and BRCA2, also play a crucial role.
Reproductive History:
Age at Menarche: Starting menstruation at a younger age is associated with a slightly higher risk.
Age at First Live Birth: Having the first full-term pregnancy at an older age is associated with a slightly higher risk.
Number of Children: Having more children and breastfeeding may offer some protection.
Personal History of Breast Conditions: A previous diagnosis of breast cancer or certain non-cancerous breast conditions like atypical hyperplasia increases future risk.
Radiation Exposure: Prior radiation therapy to the chest, especially at a young age, can increase risk.
Hormone Replacement Therapy (HRT): Long-term use of combined hormone therapy can slightly increase risk.
Lifestyle Factors: Factors such as obesity (especially after menopause), lack of physical activity, alcohol consumption, and diet can also influence risk, though these are not directly included in this simplified calculator.
How This Calculator Works (Simplified Model):
This calculator employs a simplified risk scoring model. Each input is assigned a "risk point" value based on its known association with breast cancer incidence. For example:
Older age contributes more points than younger age.
Having one first-degree relative with breast cancer adds a certain number of points.
Having atypical hyperplasia adds a significant number of points.
These points are summed up and then mapped to an estimated 5-year risk percentage. It's important to note that this is a gross simplification. Clinically validated models, such as the Gail Model (National Cancer Institute), use more complex statistical algorithms incorporating a wider array of factors and actuarial data to provide more precise risk estimations. This calculator uses a conceptual scoring to illustrate the impact of these factors.
Example Calculation:
Consider a woman aged 55. She started her periods at 13, had her first child at 27, has one sister with breast cancer, has never had a biopsy, and has had 3 diagnostic mammograms in the last 10 years.
Mammograms: This factor is more about screening frequency than a direct risk factor in simplified models, but could be conceptually weighted.
Based on a hypothetical scoring system, her total points might suggest an elevated risk over the next 5 years, prompting further discussion with her doctor about screening frequency and personal risk management.
Importance of Professional Consultation:
While this calculator can be a useful tool for awareness, it is crucial to remember that it is not a diagnostic tool. The interpretation of breast cancer risk is best done by a qualified healthcare provider who can consider the full spectrum of your personal and family medical history, conduct a physical examination, and recommend appropriate screening strategies, such as mammograms, ultrasounds, or MRIs, based on individual risk profiles. Regular screenings are vital for early detection, which significantly improves treatment outcomes.
function calculateRisk() {
var age = parseFloat(document.getElementById("age").value);
var ageAtMenarche = parseFloat(document.getElementById("ageAtMenarche").value);
var ageAtFirstLiveBirth = parseFloat(document.getElementById("ageAtFirstLiveBirth").value);
var numFirstDegreeRel = parseInt(document.getElementById("numFirstDegreeRel_breastCancer").value);
var biopsyRadio = document.querySelector('input[name="everHadBiopsy"]:checked').value;
var numMammograms = parseInt(document.getElementById("numMammograms").value);
var riskScore = 0;
// — Input Validation —
if (isNaN(age) || age 120) {
alert("Please enter a valid age between 0 and 120.");
return;
}
if (isNaN(ageAtMenarche) || ageAtMenarche 60) {
alert("Please enter a valid age at menarche between 8 and 60.");
return;
}
// Allow 0 for no birth, but validate against unrealistic numbers if birth occurred
if (isNaN(ageAtFirstLiveBirth) || (ageAtFirstLiveBirth !== 0 && (ageAtFirstLiveBirth 60))) {
alert("Please enter a valid age at first live birth (0 if never, or between 12 and 60).");
return;
}
if (isNaN(numFirstDegreeRel) || numFirstDegreeRel 10) {
alert("Please enter a valid number of first-degree relatives (0-10).");
return;
}
if (isNaN(numMammograms) || numMammograms 10) {
alert("Please enter a valid number of mammograms (0-10).");
return;
}
// — Simplified Risk Scoring Logic —
// Base points for age (increasing risk with age)
if (age >= 40) riskScore += (age – 40) * 0.5;
if (age >= 50) riskScore += (age – 50) * 0.7;
if (age >= 60) riskScore += (age – 60) * 1.0;
// Points for age at menarche (earlier = higher risk)
if (ageAtMenarche < 12) riskScore += (12 – ageAtMenarche) * 1.5;
if (ageAtMenarche = 30) riskScore += (ageAtFirstLiveBirth – 30) * 1.2;
if (ageAtFirstLiveBirth >= 35) riskScore += (ageAtFirstLiveBirth – 35) * 1.5;
if (ageAtFirstLiveBirth === 0) riskScore += 5; // Higher risk if never given birth
// Points for family history
if (numFirstDegreeRel === 1) riskScore += 10;
if (numFirstDegreeRel === 2) riskScore += 25;
if (numFirstDegreeRel >= 3) riskScore += 50;
// Points for biopsy results
if (biopsyRadio === 'yes') {
riskScore += 30;
}
// Mammogram frequency is more for screening, less for direct risk in simple models
// We'll add a minor penalty for very low frequency if age is high, as it might indicate less vigilant screening
if (age >= 50 && numMammograms < 2) {
riskScore += (2 – numMammograms) * 3;
}
// — Convert Risk Score to Estimated 5-Year Percentage —
// This is a highly simplified conversion factor. Real models are complex.
// We'll use a sigmoid-like approach to keep values within a reasonable range (e.g., 0.1% to 30%)
var estimatedRiskPercentage = 30 / (1 + Math.exp(-(riskScore – 50) / 15)); // Tuned parameters
// Ensure the result is within a plausible range
if (estimatedRiskPercentage 30) estimatedRiskPercentage = 30; // Cap at a high but realistic value for a 5-year estimate
document.getElementById("riskResult").innerText = estimatedRiskPercentage.toFixed(2) + "%";
}