Unless you cure cancer, then the topic that you researched is important. OP, cure cancer.There is also absolutely no reason to do a medicine-related thesis. The point of a thesis is to get a chance to do independent research. If you learn how to understand past literature about your topic, collect some data, analyze those data, and then are able to place the significance of your data into the greater scope of previous work, then you have completed the point of a thesis.
At the end of the day doing a thesis is valuable because of the skills you have gained and not the particular topic that you researched.