Dear CancerGRACE team
I attended the Acquired Resistance seminar in Boston. It was very informative and it took me a full month to absorb all the information provided. I have now a question to ask about dormant cancer cells in NED patients.
Once the EGFR patient has become NED, it is difficult to know whether the body is free of cancer or whether there are still cancer cells alive (inhibited and therefore invisible on the scan, and yet alive). If we knew the real situation, we could make adjustments in our treatment (I have a few ideas for myself, which I cannot detail here because of the 2000 character limit).
But first, we need to assess the objective situation. I was thinking of doing the following:
-- stop the inhibitors for five days (and let the body wash them out);
-- perform a PET-CT;
-- restart the drug immediately thereafter.
It seems to me that the scans would then provide a real picture of the remaining cancer, showing both active and dormant cells.
There is an important assumption here, which is the fact that tumours can go from NED to visible on scans within 5 days. It certainly depends on the individual patient's cancer (I guess some tumours can be harder to wake up than others). Pharmaceutical companies provide half-life values for the drugs. The half-life of Tarceva is 36 hours. I would imagine that after five days, at least a certain proportion of cancer cells would start consuming glucose and become visible on the scan. Maybe the image would not be perfect; maybe SUV values would be underestimated; but at least we would get some basic understanding of the objective situation.
In order to deal with a potential flare, I was thinking of doing intermediary blood tests during the period; if the CEA marker starts sky rocketing, I would restart the inhibitors straightaway.
My question is, does this make any sense?