Ok thanks gloriamazz. So from this description it sounds like the lesion is in the pelvic bone itself - is this correct? If this is the case then it may not respond to chemo as well as an organ with very good blood supply might, though radiation might normally be more effective. Perhaps others will have had some experience with this that they can help you with.
Have you had a PET scan either before or after treatment to confirm the metabolic activity level of the lesion?
2018 Dx RC, 12cm high
Mod diff, EMVI+ LVI+. 4 liver mets
pT3N1aM1a Stage IVa. MSS NRAS G13R
CEA: Nov-18= 14, Mar-19= 2.4, Aug-19 <2.0, Mar-20=2.2, May-20=1.9, Jun-20=2.1, Sep-20: 2.1, Dec-20: 2.3, Mar-21=2.5, Jul-21=3.1
11/18 FOLFOX x6
3/19 Liver resection
5/19 25x pelvic radiation; complete met. response
07/19 ULAR w ileo, 1/27 LN+
08/19 Found liver spot
08/19 FOLFOX x1, FOLFOXIRI x1, FOLFIRI x5
12/19 Liver resection
02/20 Ileo reversed
03/20 NED (CT/PET/MRI/scope) - latest scans Jul-21