I was advised not to have radiotherapy, as I opted for a mastectomy rather than lumpectomy and my sentinel nodes were clear. Initially, they said they didn't expect I would need chemo, however the invasive ductal carcinoma was much larger than the DCIS area indicated on the mamogram. Plus, at 45 (now 46) I am considered young, so their treatment advice is also influenced by the fact that they want me to get another 40+ years yet.
My Ki67 was low, an initial indicator that chemo may not be effective/necessary. So I was recommended for oncotype testing (EndoPredict) and had that done at a cost of $3k. This test is only recommended if you meet certain criteria regarding tumour size, type and lymph node involvement.
The tests came back showing that chemo would make very little difference to my expected outcomes and chemo was not advised as necessary.
However chemo was still an option, for the tiny % difference it would make, so technically I did opt out of chemo.
I intend to be on tamoxifen for 5 years/until menopause and then an AI until the 10 year mark unless newer research indicates a better option.
Best of luck with your sentinel node biopsy, I hope they come back clear!