Dr. West,

This was very informative and sounded a bit familiar with my case. Not identical but close enough. It has created a question though. In a lot of my reading whenever poorly differentiated cancer is discussed it is usually mentioned that the type is unknown. Does that mean that an identified adenocarcinoma really can’t be poorly differentiated because it was able to be identified? Or can it go either way. I’ll get this histology stuff down yet. Thanks. –mikem

It’s a spectrum, and the tumors that are poorly differentiated but are assigned as squamous or adeno or another histology are not as poorly differentiated as the tumors that are not able to be characterized at all. A central question is whether we can be confident enough of an assignment of squamous or non-squamous in someone with a poorly differentiated tumor, perhaps even if there’s an assignment of a histology (we know that there is plenty of variability in pathology interpretations for poorly differentiated tumors, far more than well or moderately differentiated tumors, and different interpretations even among experts). Just like tough lesions on scans, tough tumors to characterize are tough for everyone. But we can presume that a poorly differentiated adenocarcinoma had enough features for someone to make an assignment, which is more than can be said for “poorly differentiated NSCLC, not otherwise specified”.

Dr. West,

Thanks for the response. It all makes sense (I’m getting there). I think its reasonably safe to say at least that I’m non-squamous since Alimta isn’t know to work well in that histology (I’m pretty sure I read that here) and I have been having a very good response so far to that chemotherapy. Thank you very much for the explanation. –mikem

Dr West,
Is there a time frame that is considered safe to give radiation after taking Avastin? If she had been given Avastin with her chemo treatment would that have prevented her from safely getting radiation following the chemotherapy?
Myrtle

Myrtle,

This is really a largely unknown issue; the issues with Avastin and radiation are rare, and they’ve primarily been reported in patients who received Avastin and radiation concurrently. Problems in patients in whom radiation and Avastin weren’t given concurrently are even more rare, but the fact that we can’t really predict who is at greater risk at this point makes us err on the side of caution.

There really isn’t any cutoff. Avastin has a half life of about 20-21 days, so that means that someone who gets it today (say, as an ongoing dose) will have 1/4 of their current blood level in 3 half-lives, 2 months from now). The risk of any problem probably decreases steadily as you get out beyond 6-8 weeks, but I don’t think we can say if and when there is no risk. But we’re still talking about rare events — it’s the unpredictability that is making us extra cautious.