RECIST Tumor Response Calculator
Calculate tumor response using RECIST criteria to evaluate cancer treatment effectiveness by measuring changes in tumor size.
How to Use This Calculator
- Enter the sum of longest diameters of all target lesions at baseline
- Enter the sum of longest diameters at follow-up assessment
- Select whether lesions are measurable or non-measurable
- Adjust the timeframe slider to match your assessment period
- Check if new lesions have appeared since baseline
- Click Calculate to see your RECIST response classification
Formula Used
% Change = ((Follow-up - Baseline) / Baseline) × 100
Where:
- Baseline = Sum of longest diameters at initial assessment
- Follow-up = Sum of longest diameters at subsequent assessment
- % Change = Percentage change in tumor burden
Response Categories:
- Complete Response (CR): Disappearance of all target lesions
- Partial Response (PR): ≥30% decrease in sum of diameters
- Stable Disease (SD): Neither sufficient shrinkage nor sufficient increase
- Progressive Disease (PD): ≥20% increase in sum of diameters
Example Calculation
Real-World Scenario:
A 62-year-old patient with metastatic lung cancer has baseline measurements of target lesions totaling 45mm. After 8 weeks of treatment, follow-up measurements show a total of 31.5mm.
Given:
- Baseline sum of diameters = 45 mm
- Follow-up sum of diameters = 31.5 mm
- Timeframe = 8 weeks
Calculation:
% Change = ((31.5 - 45) / 45) × 100 = -30%
Result: Partial Response (PR) - The tumor has decreased by 30%, meeting the criteria for partial response per RECIST guidelines.
Why This Calculation Matters
Practical Applications
- Clinical trial endpoint assessment
- Treatment efficacy monitoring
- Regulatory approval submissions
- Insurance reimbursement documentation
- Research study data collection
Key Benefits
- Standardized tumor measurement across healthcare providers
- Objective assessment of treatment response
- Consistent communication between multidisciplinary teams
- Data comparability for clinical research
- Evidence-based treatment decision making
Common Mistakes & Tips
Frequently Asked Questions
References & Disclaimer
Medical Disclaimer
This RECIST tumor response calculator is for educational and informational purposes only. It should not be used for clinical decision making or patient care. Always consult with qualified healthcare professionals for medical diagnosis and treatment decisions. Tumor measurements and response assessments should be performed by trained medical professionals following established clinical guidelines.
References
- EORTC - RECIST 1.1 Guidelines - Official Response Evaluation Criteria in Solid Tumors guidelines
- Eisenhauer et al. - New response evaluation criteria in solid tumours - Original publication of RECIST 1.1
- FDA Guidance - Clinical Trial Endpoints for the Approval of Cancer Drugs and Biologics - Regulatory perspective on tumor response assessment
Accuracy Notice
This calculator provides standardized calculations based on RECIST criteria but does not account for all clinical factors that may influence treatment response assessment. Individual patient circumstances, imaging quality, and measurement techniques can affect results. Always verify calculations and interpretations with qualified medical professionals.
About the Author
Kumaravel Madhavan
Web developer and data researcher creating accurate, easy-to-use calculators across health, finance, education, and construction and more. Works with subject-matter experts to ensure formulas meet trusted standards like WHO, NIH, and ISO.