I am a 3rd year PhD student in cancer research. During the past two and half years, I get bored about my PhD project and gained more and more interest in neuroscience (I won't explain the how-come here). I was not sure whether I would get bored in neuroscience again (just as I did in cancer biology), so I took courses online in basic neuroscience, neural imaging, etc and read research papers and some textbooks. I also learned some programming. Now I somewhat live a lifestyle that constantly switch modes: I studied about my PhD project in daytime and as soon as I left lab, I was eager to learn more about neuroscience.

Recently, the "quitting" thoughts come again and again. My reasons for quitting is: 1, I am not excited about cancer research at all, I feel boring having to do this in daytime, I've got eagerness to study neuroscience. 2, I think doing things I am not keen on is wasting my time. 3, I am worried that I would not get a good job in neuroscience after I graduate this PhD in cancer research.

My friends persuaded me not to --- they think it would be alluring to graduate with a PhD at the age of 25. But the thing matters is not the PhD diploma itself, what matters is what I did for the PhD diploma, right?

But at the same time, I was also afraid of quitting. It would not be easy to find another PhD in neuroscience. Thinking only about getting recommendation letters for application is already a headache.

Have you ever been in the same situation or have any suggestions?

If you are nearing the end of your research, you may as well carry on now and finish. It may be possible to use your skills learnt in your PhD in a career in neuroscience, if I were you I would find out whether you can do this first. You're right that it will be more difficult to get a PhD in neuro if you have already quit a PhD elsewhere, and I don't you think you can be sure that you won't get bored in that one too.