The question, if nicotine without combustion acts carcinogenic can be - based on a plethora of research - easily be answered with NO.
Nonetheless, there is a wide misconception and illiteracy about the safety and efficacy of nicotine, when it is consumed in non-combustible ways, despite decades long research and marketing efforts conducted by pharmaceutical companies in support of the introduction and sales or prescriptions of nicotine replacement therapies (NRTs) like nicotine gums or transdermal patches, lozenges, nasal and oral sprays or inhalers, that contain the same pharmaceutical graded nicotine derived from tobacco plants as modern smokefree nicotine products like nicotine pouches or nicotine vaping product (which do contain extracted nicotine but not further processed tobacco plant materials).
It is meanwhile an established scientific consensus, that the byproducts in the inhaled smoke from burned tobacco leafs are the main contributors to smoking-related diseases, but not nicotine. Though there is no combustion, specific components (e.g. nitrosamines) in orally used smokeless tobacco leaf products that may contribute to certain type of oral cancer, but depend heavily on the specific treatment and type of consumption (see differences between Swedish snus and other orally used tobacco products).
Epidemiological studies of NRTs and Swedish snus have shown that smokeless nicotine consumption does not increase a users’s risk for developing tobacco (smoking) related diseases in comparison to non-users.
Nonetheless, for users with pre-existing conditions, the benign short-timed effects of nicotine on e.g. the cardiovascular or the digestive system, through its likewise stimulating and relaxing effects on both the para- and sympathetic nervous system should be taken into consideration. This goes likewise for users with diagnosed cancerous tumors, as some research indicates, that nicotin may support the grows of bloods vessels around those tumors.
But although not completely risk-free (an unscientific demand, which cannot be fulfilled by any other human kind of behaviour), the complete switch from consumption of combusted to smokeless nicotine offers a plethora of health benefits.
Research indicates, that the lifelong risk for cancerous diseases from using nicotine without combustion, e.g. with nicotine vaping products does not exceed 0.5% of that caused by the use of combusted tobacco products, meaning it's over 200 times less riskier.
Widespread misconceptions even among medical personal and practitioners about the benignity of smokeless nicotine are likely caused by decades of zealous campaigning from well funded anti-tobacco pressure groups, which despite all scientific evidence treat all tobacco and nicotine products equally harmful in regards of potential, especially when compared to cigarettes.