Exercise has long been hailed as cancer-fighting magic, but is there hard evidence behind the hype? In this episode, we tackle the CHALLENGE trial, a large phase III study of colon cancer patients that tested whether prescribed exercise could improve cancer-free survival. We translate clinical jargon into plain English, show why ratio statistics make splashy headlines while absolute differences tell the real story, and take a detour into why statisticians think survival analysis is downright sexy. And we even bring in a classic reality show to make sense of the numbers.
Statistical topics
- Data and Safety Monitoring Board (DSMB)
- Hazard ratios
- Intention-to-treat analysis
- Interim analyses
- Kaplan-Meier curves
- Phase III trials
- Randomized clinical trial
- Rates and rate ratios
- Relative vs absolute differences
- Stratified randomization with minimization
- Survival analysis
- Time-to-event variables
Methodological morals
- “Ratio statistics sell headlines. Absolute differences sell truth.”
- “Survival analysis is this sexy stats tool that makes every moment and every Cox count.”
References
- Courneya KS, Vardy JL, O'Callaghan CJ, et al. Structured Exercise after Adjuvant Chemotherapy for Colon Cancer. NEJM. 2025;3-25.
- Rabin RC. Are Marathons and Extreme Running Linked to Colon Cancer? The New York Times. Aug 19, 2025.
- Sainani KL. Introduction to survival analysis. PM&R. 2016; 0-85.
- Sainani KL. Making sense of intention-to-treat. PM&R. 2010;9-13.
Thanks
Thanks to Caitlin Goodrich for the episode topic tip!
Kristin and Regina’s online courses:
Demystifying Data: A Modern Approach to Statistical Understanding
Clinical Trials: Design, Strategy, and Analysis
Medical Statistics Certificate Program
Epidemiology and Clinical Research Graduate Certificate Program
Programs that we teach in:
Epidemiology and Clinical Research Graduate Certificate Program
Find us on:
Kristin - LinkedIn & Twitter/X
Regina - LinkedIn & ReginaNuzzo.com
- () - Intro
- () - Two different types of cancer studies
- () - Why might exercise affect cancer?
- () - Phase III trials are different
- () - Who was in the CHALLENGE trial?
- () - Stratified randomization with minimization
- () - The exercise prescription
- () - What did the CHALLENGE trial measure?
- () - Disease-free survival
- () - Data and Safety Monitoring Board – what do they do?
- () - Participants and adherence to exercise
- () - Intention-to-treat analysis
- () - Survival analysis overview
- () - Kaplan-Meier curves
- () - Reality-show analogy
- () - Ratio statistics are confusing
- () - Hazard ratios
- () - Wrap-up, rating, and methodological morals
