Tyrer-Cuzick Risk Calculator
The Tyrer-Cuzick Risk Model (also called the IBIS Breast Cancer Risk Evaluation Tool) is a widely used model for calculating breast cancer risk. This model assesses the likelihood of developing breast cancer based on a comprehensive set of personal, familial, genetic, and lifestyle factors. Below is a table of the most important input variables in the Tyrer-Cuzick model, along with descriptions of each factor and how it affects risk assessment.
| Input Factor | Description | Impact on Risk |
|---|---|---|
| Age | The individual’s current age. | Risk of breast cancer increases with age. |
| Age at Menarche | Age when menstruation began. | Early menarche (before age 12) is associated with higher risk. |
| Age at First Childbirth | Age at the birth of the first child. | Later childbirth age (after 30) can increase risk, as does nulliparity (never having children). |
| Number of Children | Total number of children the person has given birth to. | Higher parity (number of births) tends to reduce risk. |
| Menopausal Status | Whether the individual is premenopausal or postmenopausal. | Postmenopausal status can increase risk, especially if age at menopause is later. |
| Age at Menopause | Age at which menopause occurred (if applicable). | Later age at menopause is associated with increased risk. |
| Family History | Breast cancer history in first-degree relatives (mother, sister, daughter) and second-degree relatives. | Family history is a significant risk factor, especially with multiple affected relatives. |
| BRCA1/BRCA2 Mutation | Known presence of BRCA1 or BRCA2 mutations. | These genetic mutations dramatically increase breast cancer risk. |
| Ashkenazi Jewish Descent | Ethnic background associated with higher likelihood of BRCA mutations. | Being of Ashkenazi descent can increase genetic risk due to higher mutation prevalence. |
| Hormone Replacement Therapy (HRT) Use | Usage of hormone replacement therapy, duration, and type. | Extended HRT use, particularly combined estrogen-progesterone, may increase risk. |
| Breast Density | Density of breast tissue based on mammogram. | Higher breast density is linked with increased breast cancer risk. |
| Body Mass Index (BMI) | A measure of body fat based on height and weight. | Higher BMI, especially postmenopause, can increase risk. |
| Atypical Hyperplasia History | Prior diagnosis of atypical hyperplasia in breast tissue. | Having atypical hyperplasia can elevate breast cancer risk. |
| Lobular Carcinoma In Situ (LCIS) | History of lobular carcinoma in situ (LCIS). | LCIS presence significantly raises future breast cancer risk. |
| Hormonal Factors (OCP Use) | Usage of oral contraceptives (birth control pills), particularly duration of use. | Long-term oral contraceptive use may slightly increase breast cancer risk, though effects are complex. |
| Previous Breast Biopsies | Number of prior breast biopsies performed and results (if any abnormalities). | Multiple biopsies, especially with atypical findings, can slightly elevate risk. |
| Lifestyle Factors | Lifestyle variables such as smoking, alcohol consumption, and physical activity. | These factors moderately influence risk; alcohol intake is associated with a slightly higher risk, while physical activity may reduce it. |
Notes on the Model:
- Risk Calculations: The Tyrer-Cuzick model produces two primary risk outputs:
- 10-Year Risk: The risk of developing breast cancer within the next 10 years.
- Lifetime Risk: The probability of developing breast cancer over the course of a lifetime (up to age 85).
- Weight of Each Factor:
- The model considers each factor’s relative weight based on research correlations with breast cancer risk. For example, BRCA mutations and strong family history have a high impact, while factors like oral contraceptive use have a relatively lower impact.
- Genetic Factors vs. Lifestyle Factors:
- Genetic and familial factors are generally weighted more heavily as risk indicators in the Tyrer-Cuzick model. However, lifestyle factors contribute meaningfully to risk management and are also considered.
Usage Considerations:
The Tyrer-Cuzick tool is generally used in clinical settings, often by physicians or genetic counselors, to guide preventive measures such as:
- Enhanced screening (e.g., MRI for those with high lifetime risk).
- Preventive medication (like tamoxifen or raloxifene for high-risk patients).
- Genetic counseling or testing, particularly for those with strong family histories.