It's something I think I would find exceptionally difficult, as "should" most people.
The problem I have with this series of images is that it seems to be nothing more than an exercise on tugging of heart strings.( In the photographic sense, obviously not for the people involved)
If i was to take on a documentary of this type there would need to be a reason behind it other than, to create a series of powerful images.I would want to bring awareness to a lesser known illness or a plight of a community that has been shunned by conventional media.
The fact is that millions die of cancer every day and is the largest funded and publicized disease in the world. As heart wrenching as this story is, what separates it from all the other unfortunate people that suffer and die from it.
If you look at the work of John Kaplan another Pulitzer prize winner, you may get a better understanding of what I mean.
In particular his set on The Russian Youth and Surviving Torture in Sierra Leon. (We rarely if ever here of these atrocities on CNN)
http://www.johnkaplan.com/pages/torture1.html
As for the Mother looking through these images again, I can;t imagine it would cause anything but heart ache, would you not wish to remember your son when he was healthy and happy as apposed to being in pain and suffering. I'm more of a celebrate their lives than a mourn the death person... But thats me!