Hey @primek - thought I would share some info I got recently from my radiation oncologist (saw her 17th March).
Although my most recent radiation has been to my spine, rib & pelvis due to bony mets (over 12 months ago now) the radiotherapy I had when I was initially diagnosed with bc was to my breast only and the chest wall - not the armpit (this was checked and confirmed on 17th March).
My radiation oncologist said the greatest risk of developing lymphodema is radiation to the armpit area not simply radiotherapy in that area (breast, chest).
@Dandelion, was not recommended a garment following surgery or radiotherapy - had 15 lymph nodes removed (this was pre-sentinel node days). Just given exercises for arm to do several months after surgery and then during and after radiotherapy.
My original radiotherapy to my breast was in early 2004. I developed no symptoms at all of lymphodema until December 2016 - almost 13 years later.
So, hit and miss - I totally agree :#