We have had someone here a couple of months ago with Phyllodes. I tried to find the discussion but the search button isn't working today.
Just a word on margins. My BS kept saying "small but clear" about my re-excision surgery. I queried him on it. He was talking about 1mm in my case and explained that in Australia the minimum margin standard is set at 2mm. He said tecnichally clear by one cell is a clear margin. In the US they don't set a standard, so 1 - 2mm margins are very common there. So to me, your 5mm sounds generous!