Carcinoma in situ is an early form of cancer, so it is cancer, and can spread. I had carcinoma in situ in the tonsil, and look at my singnature, which is only half of it lol. Sounds like they did an excisional biopsy, instead of an incisional biopsy, which is sometimes preferred, since the excisional may not have clear margin sometimes, such as yours, if true, and need for another surgery to get clear margins.
