Is it absurd...

Hugs to your mom.  I'm sorry she had to join the club no one wants to join. 

For everyone, the question of what treatment to pursue is a really personal decision.  There's a couple of things she needs to consider to make a good decision.  First but foremost, her decision needs to be hers, not mine, not yours, not the docs, but hers.  To get to that point she does need to make sure that she's thinking clearly and not rushing into anything. She needs to consider the impact of possible treatments and also the impact of not treating. Hypothetically,  IF she doesn't treat it and it came back, would it bother her more than if she did treat it and it came back.

She needs to get an accurate picture of her type of tumor.  You mention the grade and the er-,pr- status but there's other information that comes into play for the doctors recommendations.  What is the her2 neu status? What size tumor for the DCIS?  Is the microinvasion multifocal or multicentric? What's the family history? Does she have lifestyle habits that will affect the recurrence rate? What is the % change in recurrence for her particular tumor  with or without treatment?  Most doctors will have considered all of this other information before making recommendations of yeah or nay.

In terms of statistics, yes they are only statistics for a group; they are not specific to an individual. They also are usually outdated or only good for the specific group of data from which they were created. That being said, we do know that for SINGLE tumors, a mastectomy is equivalent in survival versus a lumpectomy with radiation.  If there is more than one tumor, that equivalency starts to skew.  the online tools you've used are probably reasonable, but you probably want to see what the doctors use.  It takes into account a bit more information.  Again, all of these are just statistics, they're not an individual and they often are outdated.  Also be sure of the sources of your statistics.  Read the actual journals and get a look at their methodology. Don't just go by a newspaper's summary of the article which may not be accurate or present the reliability of the statistics.

You say she doesn't want to do the radiation. Again, she needs to make sure she has all the facts before she decides. Is she knee jerk reacting from fear or from examining her own situation. Has she talked with women who have done radiation recently?  It is a far cry from what it was like when she was younger and she may have some misperceptions of the current picture.  She also needs to remember that her mind is always going to expect and picture worse than reality.  She has to decide if the impact on her life would be too detrimental for 6 weeks. Again, only she can really tell but she needs to be making a truly informed decision.

You mention the radiation onc, but has she met with any other oncs to discuss other methods of follow up for recurrence?  Since she's er-,pr- tamoxofin or ai's would not be of any use to her but are there other things that might be considered?  Some people believe in doing the natural route.  Is that part of her decision making? Is she worrying more about the impact or inconvenience of others instead of the bigger picture of herself? Everything needs to go into the decision.

Personally, I would throw the book at it.  Once it has an invasive component, the foot is in the door; the question is, do you let the door swing open?  Again, that's just my opinion and she needs to decide for herself with all of the information being considered, not only what is presented here.  It's never easy but I'm glad to see she has you being proactive for her. Good luck to her.

Breast cance is an inconvenience. There is no way around this. It becomes even more of an inconvenience if you don't treated properly. I gues what I'm saying is if there is a recommended course of action and she doesn't want to be inconvenienced she is putting off the inevitable.

But yes I do understand her concerns regarding her sister. This needs to be discussed with the onologist. It just might have been some one wasn't watching her sister's white counts close enough and she cought  pneumonia. They have Nuelasta for that now. Also she might not be on the same chemo as her sister.