PET Scan Results:
Today was PET scan day. I had once thought that the PET scan would show definitively whether or not the current regimen was working. However I am currently on a study of immune therapy, and last week Dr WG prepared me for today by explaining that the current study medication could cause the PET scan hot spots to show a "flare." That is the therapy, if it is working, could actually cause previously-existing hot spots to appear larger or more intense than they did in the PET scan of four months ago, because of inflammation caused by my own immune system currently attacking the myeloma. He also told me, however, that if the therapy is working he wouldn't expect any additional hot spots to appear, beyond those already seen on the previous PET scan in October.
Sure enough, the hot spots did flare! I don't yet have numbers on how much they flared, but it was a lot, and he said that he would be very surprised indeed if the increase in size and intensity was due to an increase in tumor burden. Two of the hot spots are in my spine, vertebrae T5 and T9, and he thought that I would certainly have back pain in those areas if the flare was due entirely to the tumor. Indeed, I ran a marathon last Sunday (number 92) without feeling pain in my spine. There is one additional hot spot, in another vertebra, but Dr WG believes that it was present in the previous PET scan, just not bright enough to be noted by the radiologist.
Dr WG actually seemed to be quite enthused about the possibility that the trial therapy really is working as it is supposed to work. Last week he had related a personal experience from several years ago, where a patient (with a different cancer) was not apparently improving on immune therapy, and in fact seemed to be getting worse fast. The patient was told that nothing more could be done, and advised to go on hospice care. However, the patient walked beck into the clinic a few weeks later, completely cured, no cancer lesions remaining. The point is that immune therapy has to be evaluated differently from other therapies, whether in myeloma or other cancers.
As part of that evaluation, Dr WG has ordered an MRI of the affected areas for next week. Hopefully, we will be able to compare those MRI images with MRI images from four months ago to see if the myeloma lesions have actually grown. If they have, then plenty of other treatment options are available, including at least eight drugs already approved for myeloma which I have never yet tried. However, I really want to give this therapy every possible chance, because it is easy to take and I experience no noticeable side effects from it.
IgG and M-spike were both down slightly from last week, IgG dropping from 1510 to 1440 mg/dL and M-spike from 1.5 to 1.4, lending more credence to the theory that the flares are not due to increased tumor burden. Furthermore, IgG (including that which comprises M-spike) has a half life of about three weeks, so even if the myeloma cells are being killed left and right, the IgG proteins that they have already produced would not decline a lot in just a week.
My myeloma is IgG lambda. The lambda light chains did show a modest increase over last week, but the kappa light chains increased even more, so the ratio actually went up a little and no one really knows whether the increased light chains have any meaning.
Beta 2 Microglobulin is a tiny protein found in the blood, often used in the diagnosis of multiple myeloma. Higher values normally indicate a worse prognosis. Mine was 2.56 mcg/mL today, 21% higher than any previous value over my 12-year myeloma history, 30% higher than three weeks ago, and barely within the reference range. The doctor was skeptical that such a modest change could have any meaning, but I still wonder. Beta 2 Microglobulin can be released into the blood by the destruction of white cells, and myeloma cells are white cells, so maybe it's just possible that the increase in this test result is another indication that the flare is due to the destruction of myeloma cells. Anyway, if the increase means anything at all, I choose to put a good spin on it rather than a bad spin.
I am excited about the possibility that the therapy could be working, and if it works for me it could work for many. We keep on running, and we keep on hoping.