Within years after the first British colony in North America, people of European ancestry started smoking tobacco regularly. Lung cancer remained rare until around 1927, a few years after toxic pesticides began to be sprayed on tobacco, and they switched from wrapping cigarettes with a tobacco leaf to using paper bleached with chemicals.

https://www.nature.com/articles/s41401-019-0299-4

Nicotine is a bioactive compound in cigarettes that exerts rewarding effects by activating nicotinic acetylcholine receptors (nAChRs) in the central nervous system

Why would native Americans smoke tobacco for centuries, considering it to be a medicine, if it really caused lung cancer? It seems more likely that tobacco, pure organic tobacco, is a healer.

Alpha7 nicotinic receptors as novel therapeutic targets for inflammation-based diseases

https://pubmed.ncbi.nlm.nih.gov/20953658/

Abstract

In recent years the etiopathology of a number of debilitating diseases such as type 2 diabetes, arthritis, atherosclerosis, psoriasis, asthma, cystic fibrosis, sepsis, and ulcerative colitis has increasingly been linked to runaway cytokine-mediated inflammation. Cytokine-based therapeutic agents play a major role in the treatment of these diseases. However, the temporospatial changes in various cytokines are still poorly understood and attempts to date have focused on the inhibition of specific cytokines such as TNF-α. As an alternative approach, a number of preclinical studies have confirmed the therapeutic potential of targeting alpha7 nicotinic acetylcholine receptor-mediated anti-inflammatory effects through modulation of proinflammatory cytokines. This "cholinergic anti-inflammatory pathway" modulates the immune system through cholinergic mechanisms that act on alpha7 receptors expressed on macrophages and immune cells. If the preclinical findings translate into human efficacy this approach could potentially provide new therapies for treating a broad array of intractable diseases and conditions with inflammatory components.