 This next case is a patient also with rectal cancer and the question is a staging of the tumor. And so I'm going to show you two cases in succession. The point of these two cases is basically how do you deal with low rectal cancer? We mentioned a few points in the earlier case with musinus pathology. But in terms of rectal cancers that actually extend way down into the anal canal, there are a couple of pointers that you need to keep in mind and mention. Before we start looking at the cases, just to lay the groundwork, there are sort of three or four key points that you need to pay attention to when you're talking about low rectal cancers. First of all, as I mentioned, I need to re-emphasize that you need to be absolutely certain that this is beyond any reasonable doubt about a biopsy proven rectal cancer and it is not an anal cancer. Because as I mentioned earlier, we cannot distinguish the two. So that's the first point. The second point is for low rectal cancers that extend into the anal canal. There is no concept about distance to the meso-rectal fascia because there is no meso-rectal fascia that you can identify in this location. And so if it is at the level of the lavera or the pubo rectalis, you give the shortest distance to the lavera or to the pubo rectalis. It would extend below the level of the pubo rectalis into the anal canal then you need to talk about whether there is involvement of three structures and the three structures in succession are is there involvement of the internal anal sphincter? As I mentioned early on when we talked about anatomy, it is a little bit brighter than the external sphincter. Is there involvement of the inter-sphincteric space, which is this bright space containing fat between the internal and external sphincter and is there involvement of the external sphincter and beyond that? Now why do we try to make the distinction? Because if the tumor is confined to the internal sphincter, you can still do a sphincter sparing surgery. But once it goes into the inter-sphincteric space or the external sphincter, then these patients have to have their sphincters taken and these patients typically end up having a colostomy. So that's sort of the three key points you need to keep in mind when you're looking at norectal cancers.