Calculator Inputs
Example Data Table
This example demonstrates how multiple weighted risk drivers can change the final index.
| Age | Sex | BMI | Family History | Polyps | Smoking | Activity | Diet | Screening | Symptoms | Risk Index | Category |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 56 | Male | 31.2 | One first-degree relative | No | Former smoker | Low activity | Mixed pattern | Overdue | Bowel change | 60.8/100 | High |
| 42 | Female | 23.4 | No family history | No | Never | High activity | High-fiber pattern | Up to date | None | 0.0/100 | Low |
Formula Used
This calculator uses a weighted point model. Each factor adds or subtracts points based on common clinical and lifestyle risk patterns. The tool then converts the total into a normalized Risk Index from 0 to 100.
Weighted Score = Sum of all factor points
Risk Index = min(100, (Weighted Score ÷ 120) × 100)
Relative Index = 1 + (Weighted Score ÷ 30)
Protective adjustments can reduce the total. In this model, regular aspirin use and being up to date with screening lower the score.
Category Bands
- Low: 0.0 to 19.9
- Moderate: 20.0 to 39.9
- Elevated: 40.0 to 59.9
- High: 60.0 to 79.9
- Very High: 80.0 to 100.0
How to Use This Calculator
- Enter age, sex, height, and weight.
- Select family history, polyps, and bowel disease details.
- Choose smoking, alcohol, activity, and diet patterns.
- Enter diabetes, aspirin use, and screening status.
- Add warning symptoms if present.
- Press Calculate Risk.
- Review the result cards, graph, and factor breakdown table.
- Use the CSV or PDF buttons to save the result.
Frequently Asked Questions
1. Does this calculator diagnose colorectal cancer?
No. It only estimates an educational risk index from weighted inputs. It cannot diagnose cancer, rule it out, or replace a clinician’s assessment, screening test, or colonoscopy.
2. Why does age raise the score?
Colorectal cancer risk generally increases with age, especially after midlife. The calculator reflects that trend by assigning larger weights to older age bands.
3. Why are symptoms included?
Symptoms such as rectal bleeding, bowel habit changes, and unexplained weight loss may need medical review. They do not prove cancer, but they can raise urgency.
4. Does family history matter a lot?
Yes. A first-degree relative with colorectal cancer can significantly change screening discussions. Multiple first-degree relatives usually raise concern more than distant family history.
5. Is the BMI value entered directly?
No. This page calculates BMI from height and weight automatically, then uses that BMI band inside the weighted score.
6. Why can aspirin lower the score?
Some risk models include a small protective adjustment for regular aspirin exposure. That does not mean anyone should start aspirin without medical advice, because aspirin also has risks.
7. What does screening priority mean?
It is a simple guidance label. It highlights whether the combination of age, symptoms, history, and screening status supports routine prevention, earlier discussion, or prompt clinical review.
8. When should I seek care regardless of the score?
Seek medical attention if you have persistent rectal bleeding, unexplained weight loss, ongoing bowel habit changes, severe abdominal symptoms, or any other concerning symptom.