@Marakesh - I am coming up to 12 months since my lumps were detected - my diagnosis confirmed in early Jan & surgery in mid January. I had 4 weeks radiation prior to Easter & started taking Letrozole a few weeks later. Being 64, I'd already been thru natural menopause over a 10 year period (from age 45) & already had some arthritis in my joints and quite severe vaginal atrophy (even a kiddy sized speculum is painful.) So I was expecting the joint pain (in particular) to get worse once on Letrozole & that was exactly what happened, exacerbated by my existing arthritis.
After 6 weeks, I had a review with my oncologist & when I described my side effects - she immediately suggested I try a different 'type' of AI - and I started on Exemestane/Aromasin instead. I have not had as many side effects or as severe and am very pleased with the decision we made to change AIs.
As others have said - not everyone gets severe reactions - so all going well, you won't either!!
That is great that your BS has suggested you keep a diary for 6 weeks on any side effects - as my side effects started within 10 days & I was 'over it' by 6 weeks (and I'd been documenting them as well, even tho not asked to specifically!) (MY BS had originally told me I would be on Tamoxifen - I'd never even heard of Letrozole or Exemestane!) so was surprised when the Onc put me onto Letrozole initially.) Like you, I thought Tamoxifen was for pre menopausal women! (Tamoxifen has been on the BC radar for SO LONG, I think it is the first name that comes to the BS's mind!!)
All the best when you start taking the tabs xx .... On Letrozole, I was taking pain killers & anti inflams morning & night ..... now I just take an anti inflam at night (as much for my arthritis as anything else!) The base of my thumbs are still sore - but I had that before starting the meds as well .....