Reliability of PET Scan/cancer antigen tests?

I was diagnosed with stage IV metastatic breast cancer by a PET scan on August 31, 2017. Lesions in liver, lymph nodes, parotid gland, and pelivic bones. I was placed on Ibrance/Faslodex therapy for treatment. Progress was followed by monthly cancer antigen tests. The results of the tests showed success in the therapy with levels now lower than when I was first diagnosed. I feel wonderful and healthy. However while 3- month follow-up PET scan showed a decrease in size in the majority of lesions there was a slight increase in size of the original liver lesion. My Dr said this proves the Ibrance was not working and suggested changing me to Afinitor/ Aromasin. Which is the more reliable diagnostic tool? PET scan or blood tests? Should we give the Ibance more time before making a change?

7 Replies

  • I am being told by my oncologist that the pet scan is the most revealing as blood markers tend to fluctuate. A sudden high increase in tumor markers can be a clue to probe further but if they bounce around the same number they r not too concerned as per my team in New York . Hope that helps a little.

  • Hi, jstickrod! You raise a question very similar to one I raised on this site. I, of course, am no doctor, but if your CA levels are going down, you feel well, and your other tumors have shrunk, except for the one in your liver, you might consider asking whether this could be a case of pseudoprogression, in which a lesion will appear slightly larger on a scan because it's being infused by killer T-cells that are doing their job. If you have no new lesions, or progression in your other lesions, I've read that this could be what's happening. Good luck!

  • wow! I do hope so!! thanks for this perspective Dianne417!

  • You're welcome, spouseM! Like I said, I'm no doctor, but it might be worth asking your wife's doctor if this could be a possibility.

  • Hi Dianne417, just to set the record straight...I am not related to the originator of this post (other than being another person in the world with BC). I just was blown away by the idea that possibly an increase of Tcells may be the reason for an increase of size of a tumor...It would be great! and I hope it for jstickrod. Thank you for suggesting it!

  • Thank you, spouseM, for setting me straight. I'm sorry that you, too, have bc. Pseudoprogression is an interesting concept!

  • I understand your quandary, which one matters most? Your Doc must think the primary source is the one to target, and he/she must have their reasons. I would ask for an explanation if I were you, so I understood where this was coming from. I guess it could be something as simple as, "how did you determine that the primary tumor is the most important to control?" If I was not satisfied I would ask until I was, or get a second medical professional opinion.

    There may be those that have been at this same cross roads and have ideas and experiences that can be shared. Look on facebook for groups, one that I have found very helpful is:

    Remember that, individuals may have different outcomes, even with the same diagnosis and treatment, we are all so unique. Remember also that Docs are "practicing" medicine. They are doing their best at the time.

    I believe you will find your way, sending you healing thoughts!!


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