How many cigarettes a day can trigger a case of larynx cancer?

1 is too many: We don't know the answer to your question but, we do know that that laryngeal cancer happens way more often in people who smoke than it does in those who don't. Every cigarette does harm to the body in some way and, with the damage smoking also does to the finances, it's just not worth it in my book. If you were born after 1970, there's no excuse for starting- we know it's harmful...