alephnull-
Your positive LN puts you in the stage N1, which is regional. While pelvic LN mets are mets (that is, it is not prostate PC tissue as T3/4 would be), the term metastatic is usually applied to the cases where there are distantly discovered metastases, which is stage M1. Your lung spot would be stage M1c.
You are confused by NCI about
the staging terminology, anyone would be. Let me try to unpack it for you:
Stage T4 (note the T and the arabic numeral) refers to cancer that has grown into surrounding organs, such as the external sphincter, rectum, bladder, levator muscles, and/or pelvic wall. T stage shows how far outside the prostate it has gotten
Stage IV (note the roman numeral) refers to the AJCC Prognostic Stage Grouping, which isn't really a T stage system, it is a risk stratification system. In the latest version (8th edition), Stage IV is defined as any cancer that is at least N1 (IVA) or at least M1 (IVB). So Stage IVA is what NCCN would call "regional," and Stage IVB is what NCCN would call metastatic.
The NCI article you referred to is incorrect and out of date (I wrote to alert
them). In the AJCC 7th edition, all stage T4 fell into stage IV. T3a and T3b fell into stage III, in which they remain in the new edition. They are IIIB if the gleason score was 6-8, IIIC if the Gleason score was 9 or 10. (In fact,
everyone with GS9 or 10 (and not N1 or M1) is now stage IIIC).
Here's an article about
the new AJCC system:
/pcnrv.blogspot.com/2017/03/prostate-cancer-staging-update.html