We have (2) experimental mice groups subjected to different doses of cancer medication and I need to determine the time it took for each group to reach 1000mm^3. Do I calculate this based on only those mice whose tumor's reached 1000mm^3 and average the days for those respective mice? To account for +/- days, (i.e. "time for tumor size to reach XX+/-XX in X group...) do I need to perform a t-test or ANOVA? I'm a novice at biostats and am completely lost at how to approach it accurately. Also, how do I calculate an initial response to treatment with a tumor decrease?
Hi Paul,
Am just wondering, are you trying to test the efficacy of the drug? Did you include a vehicle control group?
Assuming you are trying to deduce drug efficacy, this is how I usually run my studies.
I will have a vehicle group, and my treatment groups. My endpoint will be days, rather than a specific volume. Say i start treatment when the cohort average reaches 300mm^3 and randomized, for 5 doses, and my endpoint is one week after the last dose. I will then calculate the tumor growth inhibition percentage (TGI%) of each treatment group against the vehicle group.
The formula to calculate TGI is (CdayB−TdayB)/(CdayB−CdayA) X 100, where C is the control group, T is the treatment group, dayA is the mean tumor volume on the day of first dose and dayB is the tumor volume at the endpoint.
To determine if there is significant differences between each treatment group vs vehicle, I will use Two-way ANOVA followed by Tukey’s multiple comparisons test.
But I guess ultimately, if you want volume as endpoint, I guess you can take the day for each mouse to reach 1000mm^3, and average out the days it takes for the group to reach the said volume. I will still use the same stats to analyze the data which is the two-way anova.
Just my two cents.
Hope this helps!