This is my first post. I am a clinical oncologist and have basic knowledge in statistics and a lot of motivation to learn more. So please respond accordingly. I have searched this forum for an answer to my question but could not find it.
I currently working with epidemiology research. I have collected data for roughly 500 lymphoma patients over a 20 year span. Data include gender, date of diagnosis, age at diagnosis, date of eventual relapse, date of last follow up and status at last follow up.
I am interested to explore how the shape of hazard ratio after an intermediate event (in this case relapse) depends on the time to occurrence of this event and/or the sojourn time in this state. Obviously not all patients experience relapse and relapse timeframe differs from e.g. 1 months - 10 years after initial diagnosis. So from my understanding this is a multi state model with 3 states.
I could only find one paper addressing this issue: https://pubmed.ncbi.nlm.nih.gov/23786493/
As a clinician with basic programming skills in R, I could only understand the concept but I have no idea how to do this in R.
Question 1: I want to find background theory on this, e.g. book, paper
Question 2: Can someone here open the subject and explain pros and cons of different methods in plain semi-easy statistical language
Question 3: How can this be done in R, example code, at least how to start it.
Thank you all in advance, looking forward to a productive discussion.