rads percentages

Just wanted to update this thread with more information in case other people are seeking it out. I found a couple studies with some good info:

Effect of radiotherapy after breast-conserving surgery on 10-year recurrence and 15-year breast cancer death: After breast-conserving surgery, radiotherapy to the conserved breast halves the rate at which the disease recurs and reduces the breast cancer death rate by about a sixth. These proportional benefits vary little between different groups of women. By contrast, the absolute benefits from radiotherapy vary substantially according to the characteristics of the patient and they can be predicted at the time when treatment decisions need to be made.

Effect of radiotherapy after mastectomy and axillary surgery on 10-year recurrence and 20-year breast cancer mortality: After mastectomy and axillary dissection, radiotherapy reduced both recurrence and breast cancer mortality in the women with one to three positive lymph nodes in these trials even when systemic therapy was given. For today's women, who in many countries are at lower risk of recurrence, absolute gains might be smaller but proportional gains might be larger because of more effective radiotherapy.

This second study was boiled down to me by Dr David Gorski as follows: "Post-mastectomy radiation therapy is associated with a decrease in risk of local recurrence over 10 years from 26.8% to 8.1%, whereas in women with node-negative disease the difference is not statistically significant."

I was shocked to hear that the risk of local recurrence is 26.8% with a mastectomy, 8.1% with mastectomy and radiation. Really? I thought mastectomy alone has a 5% risk of local recurrence - because there isn't much place left for it to recur!! I'm so confused....