I really think that is up to the dr. I remember my last round with cancer, had the pet before, then after treatment was done, another pet was done at next scheduled dr.s visit. that was about a month after treatment was over. Each case will be different, your dr's may want one sooner, or may want to give a few rounds of chemo to see how it works. Again, all of us are different. If your concerned just ask the dr. I fire all sorts of questions at them when I go, make a list so you don't forget. Good luck with the treatments for your wife, I hope they are swift and easy.

My doctor had me do a CT/PET scan about a month after my last chemo treatment to compare with the one I had before chemo.

I don't know when you OUGHT to have such a scan, but I do know that you CANNOT have a PET scan until at LEAST 4 weeks after chemo is over. If you do it sooner, the results are useless. Lots of stuff will show up that is not really there.

A CT scan can be done at any time. Whether it should be done is a different story.

It depends upon the doctor, yes. But, it also must depend upon the type of cancer, its aggressiveness, and its staging. For those with say, a rare Peripheral T-Cell lymphoma (non-Hodgkin's), for which there is no standard treatment, scans shortly after beginning chemo are entirely appropriate. What must be remembered is that both the chemotherapy and the cancer are quickly destroying your health. Yet, if the chemo is not destroying the cancer, it is only helping the cancer to destroy you. In such aggressive or highly aggressive cancers, immediate improvement must be seen, or alternative treatment should be considered.

In my limited experience with those suffering from this type of lymphoma, I have seen two cases where the the primary therapy failed and the patient went to a salvage regimen. That also failed and the inevitable infection set in - thus stopping even a perfect treatment from being initiated. Both survived one month after failing their salvage regimen.

The question becomes whether or not scanning was frequent enough, or if the ineffective treatment was allowed to continue for too long. It is a balancing act, and second opinions as well as treatment outcome data from worldwide experience with such malignancies can be very helpful.