ASCO Post has a great video featuring a discussion between Dr. Julie Vose and Dr. Bruce Cheson. (Of course I'm going to think it's great -- it features Dr. Bruce Cheson!) The discussion took place at the 2016 Pan Pacific Lymphoma Conference in Hawaii (which explains Dr. Cheson's great shirt, though I wouldn't be surprised if he wore a shirt like that all the time, just because it made him happy).
The video looks at how lymphoma is staged -- that is, how oncologists determine how widespread the disease is in the body. They look especially at how PET scans can play a role (or not play a role) in staging.
Scans have become more controversial over the last few years. There seems to be some agreement among oncologists that scans are a good idea for initial staging -- figuring out where the disease is in the body, to help determine the best course of treatment. There is much less agreement on how useful scans are after that point (though most oncologists see some value in a scan after treatment, as a way of measuring how well things went since that initial scan at diagnosis).
This doesn't even get into the problems with scans to begin with -- there's a lot of room for different people to administer and read scans in different ways, making them tough to compare.
(Lymphomation.com has some basic information about PET scans that is worth looking at if you need some background.)
In the video, Dr. Cheson and Dr. Vose discuss some of the history of PET scans, as well as some of the other tests used before (including one that involved injecting blue dye between a patient's toes -- makes drinking those barium milkshakes seem like fun). It wasn't until about 2007 that PET scans became an expected part of staging (which is interesting to me, since I was diagnosed, and scanned, shortly after that).
Dr. Cheson mentions that CT scans with contrast don't do much better than CT scans without contrast, though the contrast ends up giving 50% more radiation to the patient, and is more expensive. there are some situations where contrast helps, but mostly it doesn't.
In addition, PET scans can replace Bone Marrow Biopsies in some lymphomas. (Unfortunately, Follicular Lymphoma isn't one of them -- we still need that BMB.)
Scans are most useful about 6-8 weeks after treatment, since it can take that long for inflammation to come down. This post-treatment scan is known as a "re-staging scan."
However, routine scans after that re-staging scan are discouraged. They rarely pick up that the disease has progressed. In fact, about 80% of the time, a patient is the first one to pick up a symptom and report it to the oncologist. Having a scan once a year is unlikely to find something before a patient notices some kind of change. Routine scans only add radiation to -- and subtract money from -- the patient.
All in all, a pretty interesting video, with some good reminders about when scans are useful, and why we shouldn't rely on them too much.
Plus -- that shirt!