Curing (removing moisture from food by means of salt) is a distinct process from smoking (adding smoke to food as well as removing moisture via heat). Curing with nitrite and nitrate based salts (sodium nitrate and sodium nitrite) is what’s been implicated in cancer.

Smoking meat is much more complicated from a chemistry perspective. Different types of wood, different temperatures, moisture content, salt content, and cooking durations can all affect the concentrations of carcinogenic compounds in the food. For example, softwoods (such as pine) tend to produce a lot of polycyclic aromatic hydrocarbons (PAHs), a known class of carcinogens, but thankfully softwood is undesirable as a smoke wood anyway so is rarely used.

Smoking technique can also dramatically affect the result. Poor smoking technique allows the wood to smoulder at a lower temperature, producing a harsher smoke with more carcinogenic, toxic, and bitter compounds. Expert smoking technique uses a smaller, hotter fire which produces a much cleaner smoke that also results in better flavour.