What is a seton?

Can someone tell me what a seton is?
I had a perianal abscess drained almost 3 years ago, the abscess was as big as the surgeons fist. It is still not completely healed as I have a small area at the end of the incision(which is now a scar) that will not heal. It will fill up like a small ball and then relieve itself every 2 weeks or so. The last time it was about a month and I thought, it finally healed but it didn't. My surgeon has been wanting me to consider surgery but I'm scared to make the situation worse. He also told me if it doesn't heal, there is a greater chance of cancer.
Any advice?

You might like to look at the "abscesses and fistulae" link in my signature. Lots of information in there, including stuff about setons.

Best wishes,

Ivy.