While understanding that radiation has its medical demerits, I question this recommendation as possibly ageist and $$$ oriented. While mortality may not decrease for those with early stage BC who do not choose radiation at age 70 and above, recurrence risk remains and may even increase with age. So if you have a lumpectomy at 70 with no cleanup radiation, how about the possibility of mastectomy at 75 or 80, especially if a woman cannot tolerate AI's? https://pubmed.ncbi.nlm.nih.gov/32441018/
There is no doubt that no radiation and AI's are less expensive than radiation treatments, a cost analysis benefit which insurance and hospitals no doubt prefer. I recommend checking with your BC surgeon, medical oncologist, and radiation oncologist when making this important decision.