Just thought I'd chime in here. My sister (31 at the time) also had extrahepatic CC located on the common bile duct (diagnosed Sep 09). She had a Whipple done (removed gallbladder, ~12" duodenum, head of pancreas, bile duct) and had clean margins but 2/37 lymph nodes affected.
She did 8 cycles of Gemzar/Xeloda (2 weeks on, 1 off) and tolerated it well. I think cycle 5 or 6 got her where she hit critical saturation and vomited almost immediately upon finishing chemo (so keep a lookout for the cumulative effect). No radiation at the time because her oncologist said there wasn't really something to direct the radiation at (much like you pondered in a previous post).
She had clean scans until Sep 2011 when they found a necrotic lymph node and a recurrence of CC in the node. She's since done 5 treatments of SBRT and has just started a chemo regimin of FOLFIRINOX.
To give my 2 cents? I say do as much adjuvant chemo as you can tolerate. You had no nodal involvement and a small tumor by comparison (I think my sister's was 5cmx2cmx1cm) but this cancer is crazy. Write your name on the lawn, set it on fire and cry about why you don't love it crazy.
I'm linking this 2007 case study where a 60s Japanese woman had curative surgery on her extrahepatic CC (no nodal involvement) and then had it come back in a lymph node nowhere near her original tumor location. Just to point out how crazy this cancer is. Punch you in the face, steal your lunch money and then shocked that you don't like it crazy.
As far as radiation? I don't know what to do about that. In retrospect, I suppose my sister should have done radiation? I really have no idea, but the radiation oncologist mentioned recently that they don't like to do radiation to a site that's already received it. I also don't know if that's true or not but I'm simply passing that information along. If it was true I guess it's a question of keeping a bullet in the chamber?
I'm also including her bloodwork from the 09 chemo so you have some frame of reference:
ANC <I don't see this on her old bloodwork sheet
After 1 dose:
Before final dose:
WBC and Plat fluctuated pretty widely treatment to treatment. Hope this info helps!