1. What is Lung Cancer Doubling Time?

The doubling time (TD) of a lung cancer tumor is the time it takes for the tumor volume to double in size. This measurement helps assess tumor aggressiveness and growth rate, with shorter doubling times indicating more aggressive cancers.

2. How Does the Calculator Work?

The calculator uses the following formula:

Where:

• \( TD \) — Tumor doubling time (days)
• \( V1 \) — Initial tumor volume (mm³)
• \( V2 \) — Final tumor volume (mm³)
• \( t1 \) — Time at initial measurement (days)
• \( t2 \) — Time at final measurement (days)
• \( \ln \) — Natural logarithm

Explanation: The formula calculates the exponential growth rate of the tumor and determines how long it takes to double in volume.

3. Clinical Importance of Doubling Time

Details: Doubling time helps in:

• Assessing tumor aggressiveness
• Monitoring treatment response
• Predicting disease progression
• Determining optimal screening intervals

Typical doubling times range from 30-400 days, with values under 100 days considered aggressive.

4. Using the Calculator

Tips:

• Enter volumes in consistent units (mm³)
• Time interval should be in days
• Ensure final volume is larger than initial volume
• Time points should be in chronological order

5. Frequently Asked Questions (FAQ)

Q1: What is a normal doubling time for lung cancer?
A: There's no "normal" but generally: <100 days (aggressive), 100-400 days (intermediate), >400 days (indolent).

Q2: How accurate is volume measurement from imaging?
A: CT scans can estimate volume within 10-15% accuracy for spherical lesions. Irregular shapes may have higher variability.

Q3: Does doubling time change during treatment?
A: Yes, effective treatment should increase doubling time (slow growth) or show negative growth (regression).

Q4: Can this be used for other cancers?
A: The formula applies to any exponentially growing tumor, but interpretation of values differs by cancer type.

Q5: What if my tumor isn't spherical?
A: Use the formula with estimated volumes. For irregular tumors, 3D reconstruction provides most accurate volumes.