Hi Joanne,
I'm sure many if not most of us can relate to some of the frustrations your friend is experiencing in dealing with cancer. Thanks for being such a good friend to her.
It's hard to know exactly what happened without actually seeing her record. But here's my guess. The plan might have changed because further information came through on the pathology results of the tumor once it was actually removed; we also already know they did not get clean margins, which alters the plan as well. Other possiblilities are that the surgeon and oncologist weren't completely on the same page or that your friend might have missed it. Because radiation is pretty standard, especially with lumpectomy as opposed to mastectomy, (though even with mastectomy, they often still do radiation).
Chemotherapy is designed to kill any invasive cells that "got away" from the original tumor site and have the potential to metastasize, ie spread, and cause cancer to grow in distant organs. Metastasis is what people who die of cancer die from. Chemo also does a nice job of shrinking or eliminating invasive tumors in the breast as well. (People with large tumors > 3cm often receive chemo first in order to shrink the tumor to make it more manageable for surgery; people with smaller tumors usually receive chemo after surgery as the tumor is already fairly manageable, ie you're likely to get clean margins while still preserving normal breast tissue - an asset to be large breasted here.)
Radiation, OTOH, is designed to clean up any cells that were "left over" from the surgery, because if they're not removed, even miniscule ones, they can grow again. That's the difference.
However, all (surgery, chemo, radiation) work TOGETHER to help prevent a recurrence both locally (in the breast, ie radiation) and distally (in other areas of the body, ie chemo). The hard part about breast cancer is that, even with all of this, there is never really a guarantee that the cancer won't come back either locally or distally over time (and there's no set time to say it won't come back, BC is one of those that can come back many years later, unfortunately). That's why they try to be as aggressive at the outset as possible. The time to fight is NOW. (The good news about a recurrence in the breast, though, is that you probably won't die from it.)
Usually three docs are involved: a surgeon, an oncologist, and a radiation oncologist. Sometimes the information you get from each one is a little different. They usually say things like, "The oncologist will go over that with you", because each might approach things a little differently and one doc will never presume to speak for another, but generally, treatment is often pretty standard (though make no mistake, each case is unique and there may be factors that have to be taken into account which are different from someone else's case, etc).
I was told from the outset that I would need surgery, chemo and radiation, but the specifics were kind of up in the air until all results for my particualr tumor were in. For instance, I was told I'd definitely need chemo based on the fact that on biopsy, my tumor was invasive. (This differs a bit today.) However, once they removed the whole tumor and lymph nodes, they saw that my sentinel (ie first) node was positive, that altered the plan in that I had to get 4 more doses of chemo than they'd originally hoped. Another example: they knew I'd need radiation, but specifics weren't discussed. Once I met with my radiation oncologist, she explained she'd be not only treating my breast, but my axilla (underarm, where nodes were) and above my clavicle and neck, because there was a small chance of recurrence there and, as she put it, she wanted to give me my best shot of avoiding a local recurrence that she could (it's also called a local metastasis to confuse the issue even more). She only told me this when I asked why I was in the CT scanner so long for planning (and she pulled up a chair when she explained it in a very serious manner, which made me a little worried; I remember crying on the way home that day - because here I thought radiation was going to be "easy" after all I'd already been through). The type of cancer I had was not hormone related so I couldn't take medications like many with BC can to keep it away (which seriously bummed me out at the time), and it had a high chance of recurring in the first two years, those are two of the reasons they were being so aggressive at the outset; also because it was grade 3, the most aggressive, ie likely to recur. (Being a nurse when you go through something like this is both a blessing and a curse, LOL.)
There are other factors they consider as well, such as size of the tumor. (That was one good thing for me, mine was relatively small at 2.1cm, thank God for small favors.) So with your friend, they're looking at all of this. One difference between my case (6 yrs ago) and cases diagnosed today is that today, they're actually studying the GENETIC DISPOSITION of the tumors so that they know which are likely to recur, which drugs the tumor will or will not respond to, etc, which is great and which definitely is an improvement over what was available to me. So that's good news!
The bad part is that going through all of this is very scary. But more and more of us are surviving as treatment improves. So tell your friend to hang in there. It's a PIA to live through, but it's all for good reason.
Hopefully my ramblings made sense and were helpful.

Any other questions, please ask.
PS I think the shots are probably Herceptin-related. If they are, their availability has improved survival rate for that type of tumor by 50%, which is great. The downside is that herceptin positive tumors have a higher rate of recurrence, also.

But let me assure you that MANY, MANY women who have unbelieveably scary cases are doing great years later. (And unfortunatley, a few who have less serious cases aren't. That is why breast cancer is called The Beast, in large part because of its unpredictability in nature.)