The Meaning of 'Stable Disease'

Until yesterday I thought my disease was stable after cycle 1, as in unchanged. The doctor did use the exact phrase 'stable disease' and did not seem unpleased. But yesterday, reading the radiology report from that cycle 2 day 1 scan:

Enlargement of a precarinal lymph node is seen now measuring 3.2 x 3.2 cm in size compared 2.4 x 3.0 cm previously.

A subcarinal lymph node is now seen measuring 1.6 x 2.0 cm in size. 

Besides the original tumor being larger, I think that means there's two now. The report from the previous, baseline scan said:

Right paratracheal lymph node has enlarged measuring 3.0 x 2.4 cm.... No pulmonary nodules are noted. 

I talked to the trial coordinator. As it turns out the phrase "stable disease" in a clinical trial has a specific meaning. So-called RECIST criteria are used to classify changes to tumors. They take the average of the original lesions' current length(s) on their longest diameters and compare them to same average calculated at baseline.

• Growth, but not more than 20%, is considered stable disease (SD). 
• Shrinkage, if seen as 70% of the original baseline or less, is considered a partial response (PR). 
• If the average exceeds 20% growth, that is considered progressive disease (PD).

So by those criteria I did in fact have 'SD' stable disease on the original tumor -- its longest diameter increased only slightly from 3.0 to 3.2 cm. Apparently a possible new 2nd tumor not seen at baseline, doesn't throw things off, at least yet.

I said this doesn't sound stable to me. He explained the RECIST criteria above, and how they use them. If it's decided at a future scan that the 20% level has been exceeded, they would usually consider that to be "unconfirmed progression". At that point they would usually do 1 more cycle. If the >20% was still seen, that would then be "confirmed progression" and I would be out of the trial.

He said the increase in size could be inflammation due to tumor infiltrating lymphocytes (TILs) being attracted to the tumor as an effect of the immunotherapy. So I will keep that in mind in the lead-up to the next scan in 4 weeks.

Here are some test tube packs for the Monday and Tuesday draws this trip, part of my payment to BMS:

One thing I didn't mention earlier, is that I might not have gotten into this trial with only the single original lesion. Of the 16 trial slots available, 11 required a second tumor, to allow additional biopsies without disturbing the original tumor. Apparently the act of a biopsy can make a tumor 'angry' and disrupt the size measurements from baseline. But I got in on one of the 5 trial slots that didn't require a separate tumor for that purpose. Although it sounds like there is a second one now.