The answer is it varies a lot on how quick the remicade/humira anti-tnf protein is entiry gone from one's body Some can use up an entire biologic dose within a few weeks time (when antibodies and a lot inflammation is present). Otherwise at least a couple months or longer is cited. Some of us flush proteins from our blood faster than others do.
The increased cancer odds and incidence rates so low that there's been a question in a number of research studies on whether cancer rates are in fact rased at all by biologics. The Crohn's and Colitis Foundation of America has a good presentation with actual odds of cancers, very, very long odds:
Webcast:
programs.rmei.com/CCFA139VL/presentation/player.htmlTranscript
: http://www.ccfa.org/assets/pdfs/risk-and-benefits-transcript
.pdf