# Model the effect of treatment on mutation burden

I am struggling a bit to model the following problem. Basically, I would like to model tumor mutation burden (mutations per megabase, a continuous) as a function of treatment (categorical). The following is an example of how data looks like

patient-id therapy-1 therapy-2 therapy-3 cancer-type TMB
PID-1      1         NA        1         CT-1        1.3
PID-2      0         0         1         CT-1        0.14
PID-3      NA        0         1         CT-2        5
PID-4      1.        1         NA        CT-3        2.3
PID-5      1         1         NA        CT-3        10
...
...


1 - treated; 0 - not treated; NA - No information

I was trying multiple linear regression, but in most cases one patient got multiple therapies. This is where I am confused on how to interpret the results of linear regression. So far, I haven't included the cancer-type information into the model. However, IMO, including cancer-type into model will yield specific treatment effects in specific cancer type? Or is it over-expectation of what we can achieve from linear model?

Also, is there a better way to address the problem to get reasonable associations between treatment and TMB in this case?

Thank you for the help. Stay safe!

• Could you post your model is it something like TMB ~ cancer-type*patient-id ?
– llrs
Sep 29 '20 at 8:26