How do you know treatment works Flashcards
Schematic of cancer growth
Lots of proliferation of cancer cells before symptoms appear clincally
After this, there is only small window for treatment before death
Screening increases this window
What are the 3 objectives of treatment?
- Cure - kill all cancer cells
- Prolong survival - kill most cancer cells (in remission)
- Pallaite symptoms - improve QoL
What is tumour response?
Positive response to treatment e.g. tumour shrinkage (as opposed to tumour progression = treatment failure)
What is the RECIST criteria?
Used to asess tumour INDIVIDUAL PATIENT response w x-ray/CT - diameters/length of all lesions added
- complete response: NOT CURE, in remission, signs of disease gone
- partial: reduction of tumour vol by >30%
- stable disease: no change
- disease progression: increase in tumour vol >20% OR metastasis occurs
Does tumour response mean ncreased surival?
NO - cannot conclude this w/o comparison
They may have survived that long anyway wo treatment
Overall survival vs disease-free survival vs progression free survival
Overall: start of treatment –> death
Disease-free: start of treatment –> relapse (time in remission)
Progression-free: for cancers where patient is never disease free, time that disease is stable after start of treatment
What is selection bias in clinical trial?
selection without randomisation + blinding
Disadvantage of using historical controls in single arm clinical trial
Differences between patient baseline charecteristics
Different supportive care in the past –> different SEs e.g. new treatment used w anti-emetics
Historical surival could be impacted by the SEs
What is the Hazard ratio for death?
measure of the relative difference in survival between New & standard treatment (risk of death w new/risk w old)
e.g. HR of 0.6 means 40% reduction in risk w new treatment (higher = better)
