[Falkon1313]

It is possible to make them less carcinogenic. Carcinogens come from fertilizers and pesticides (which could be controlled/replaced), from the curing process (which could be replaced with anaerobic curing), and from additives (which could not be added). So a lot could be removed, but there is still inherent bad stuff in breathing smoke. That's enough to cause blowback from people who are afraid that advertising "safer cigarettes" would encourage more people to smoke. Lengthy expensive IP/patent lawsuits have also delayed development. And of course there's the issue of whether customers like it, whether it's profitable, and how much it cannibalizes the tobacco company's other business.

Possible to improve? Yes, perhaps significantly. Economically and politically feasible? Maybe not so much.