The Problems with PET-CT

This is going to be one of those posts where I respond to comments from an earlier post, because just adding another comment won't do the job.

A few days ago, I had a regularly scheduled 5 month (or so) appointment with my oncologist. He mentioned scans -- and why he wouldn't recommend my getting one. I was fine with not getting a scan (my last one was in June 2014). And he was OK with my not getting one.

I mentioned that in the blog, probably not in as careful a way as I should have, that scans aren't always a great idea for Follicular Lymphoma patients. The comments that followed that seems to have stirred up a little bit of concern. That is, of course, the last thing I want to do with a blog post.

So let me talk about scans just a little bit.

As one commenter said, scans for indolent FL are controversial, and there does seem to be more reluctance to use them for those patients. As I said in my comment, and the other commenter also noted, scans involve radiation, and when you're looking at potentially 30 more years of being an FL patient, that's a lot of radiation that builds up over time. And excessive radiation can potentially cause secondary cancers (potentially -- there's no magic formula that says how many scans to have, and how often, to avoid secondary cancers).

So are they necessary? Or even useful? Should you have them at all?

First off, let me make something clear -- when I talk about scans, I mean a combined PET and CT scan. There does seem to be some agreement in oncology that the combination is more useful than just a CT. I sometimes refer to scans as just CT scans, but I really mean a combined PET and CT -- I've never had just a CT for my lymphoma. Without getting too much into it, a CT will show if there is anything abnormal, while a PET will show if there is metabolic activity in that abnormality (if the cells are eating up a lot of the sugar that was in that nasty stuff they made you drink before the scan). Cancer cells tend to eat up more sugar, more quickly, than normal cells.

Lymphomation has some basics on PET scans. They also have a handy chart that lays out when PET-CT scans are used in different types of lymphoma. This is the section on Indolent Lymphomas like Follicular Lymphoma:




First of all, notice the title above the chart -- oncologists don't agree on much.  Most use PET-CT after diagnosis to help stage the lymphoma (remember that staging has to do with how widely it spread through the body). So that makes sense, and "most do" use it then. It helps to have some kind of base line.

The next possibility for when it could be used is "interim treatment response." In other words, if you are scheduled for 6 rounds of a treatment, does it help to know if it's working after 3 rounds by having a scan? That's listed as "investigational." There are some studies trying to figure out if knowing that information is helpful. If it's not working after 3 rounds, do I stop and try something else? Or doe we go the full 6 rounds because sometimes things take longer to work? That needs some investigation.

The next possibility is "post-treatment response." This is also controversial, though most oncologists do it. Again, this makes sense -- after those 6 rounds, we want to see if it worked (whether or not we did a scan after 3 rounds). Compare the post-treatment scan to the initial scan and you can see how well it worked.

Finally, there is "Surveillance" -- just getting a scan to see how things are looking inside, even if there don't seem to be any problems. As the chart says, most don't do this anymore. Unless there's something specific that you're checking on and looking for, if there's no reason for the scan, it's not worth the extra radiation.

So why are some scans "controversial"?

Well, a post from ASCO sums it up -- PET scans aren't any better than clinical exams (blood work or noticing symptoms) in figuring out whether or not to begin treatment. And they come with all of that radiation.

**********************************

So what should you do?

I'm afraid I'm not going to give you an answer to that. You and your oncologist should talk about it. A lot. Especially if you have concerns.

I will, though, give you a summary of my experience.

When I was diagnosed, I has a PET-CT as part of my initial staging, along with a biopsy and a bone marrow biopsy. After that flurry of appointments at first, the oncologist said we would look at things again in a month. I assumed he meant I would do another scan in a month. But he didn't. Instead, he saw that I wasn't developing any other symptoms, so over another couple of months, it seemed clear that my FL was taking an indolent course -- nice and slow.

Two years later, I noticed some swelling in my left leg.I was no longer asymptomatic, so it made sense to have a scan then. The scan showed some nodes pushing on things that led to the swelling, and letting that go would have caused lots of problems. So I began treatment (Rituxan).

After 3 rounds of Rituxan, Dr. R gave me a physical exam, and saw that the nodes were less hard, and not as noticeable. He called it a Partial Response, and based on that exam, decided to do a full 6 rounds of Rituxan, since it seemed to be working. So no "Interim Treatment Response" scan -- only clinical exam to figure out there was a response.

After treatment was over, I had a scan, which showed a Partial Response (my biggest 6 cm node went down to 3 cm, or about 2 inches down to 1 inch).

That was in March 2010. I didn't have another scan until June 2014. At every appointment, Dr. R would say, "We can do a scan, but I don't see any reason to." But then, after 4 years, he said, "Let's see what's going on in there," and I agreed, because I was curious. I was feeling well, with no symptoms, but I also knew that Rituxan can keep working for a few months after it has been given. So maybe I had a Complete Response all this time and didn't know it? (It turned out I had not had a CR).

So there was no clinical need for a scan in 2014, but I got one anyway.  I have said many times that Follicular Lymphoma is an emotional disease as much as a physical one, so I would call that one an "emotional scan" -- I just needed to know what was going on inside me. I think I've dealt with the emotional aspects of having an indolent cancer pretty well (blogging helps). But sometimes, even after 6 years of having it (which is where I was in June 2014), a little fear creeps in.

So I was glad I had the scan then, even though it wasn't physically necessary.

This last visit with Dr. K, he mentioned scans again. As he put it, "The Academics are telling us not to do them too often." I know that he uses guidelines from NCCN (National Comprehensive Cancer Network) for a lot of what he does. NCCN is a little vague when it comes to scans for Follicular Lymphoma; it says that you shouldn't do a scan any more often than 6 months, for two years after treatment than resulted in a PR or CR. After two years, no more frequently than once a year.

When I mentioned that in a comment on my last post, that scans shouldn't happen more than once a year, it was the NCCN guideline that I was referring to.

For me, I'm coming up on two years now, and I'm happy to not have another one. I'm not showing any symptoms, and I don't feel the need to see what's going on inside.

Dr. K did say that if I wanted one, he would schedule one. I think that's his recognition that this is an emotional disease.

So, should you have a scan if you're not showing physical symptoms? I think that's something you and your oncologist have to discuss. I had one after 4 years, and I knew the long-term risks that came along with it.

But I don't plan on making that a habit. Maybe if your emotions are getting the best of you, and you really feel like you need one, it's worth waiting another 4 or 6 months? No sense in making a decision based on a bad day. But maybe taking a long time to think it over, and maybe decide that, since you're going to be around for a long time, it's not worth the radiation, would turn out to be the best choice.

Good luck with your decisions, every one. Remember that you have a voice to talk to your oncologist, and a brain to think things through, short- and long-term.