My understanding is that 3 weeks tends to be the standard now, as it's been found that a shorter course with higher dosage is just as effective & well tolerated as a 5 week course, which used to be standard practice.
Obviously, treatment plans can vary depending on specific issues.
I met a lady in hospital having same treatment for dcis. We both hade to have re-excision. She tells me she is having 5 weeks radiotherapy but I am olnly having 3 weeks. My dcis was high grade. What would be the reason for this ?