For example imagine a patient with hypopharyngeal T4N1 SCC whose diagnosis was made on 2011.05 but he was referred for definitive radiotherapy at 2011.9 after a couple of courses of induction chemotherapy. His RT ended in 2011.11 and he died in 2012.06 due to his cancer. This 8 month gap between diagnosis and end or RT is substantial!!!!
YOU define how you want to measure survival. Completely up to you. You may want to measure it since diagnosis, since end of therapy, or other time points. The important thing is to interpret the results accordingly. And yes, it's a substantial interval in your example but as long as you know what you are looking at, you are fine. Each definition has its potential caveats.
In publications date of diagnosis is mostly used as the reference point as mortality from definitive radiotherapy or early recurrences are not accounted for otherwise. See NCI definitions for endpoints in cancer studies.
- Badges
- Science topic
- Similar topics
- Geoscience
- Asia
- India