Smoking Status, Including Non-Combustible Nicotine or Tobacco Products Use, and Site-Specific Colorectal Cancer Risk: A Nationwide Cohort Study

Abstract

Simple Summary As smokers increasingly switch to or combine combustible cigarettes (CCs) with non-combustible nicotine or tobacco products (NNTPs), including liquid-type e-cigarettes and heated tobacco products, how smoking status and changes in use patterns relate to colorectal cancer risk remains unclear. In this nationwide Korean cohort of over 4.4 million adults, compared with never smoking, exclusive CC use was associated with the highest overall colorectal cancer risk, with elevated risk across the colon, rectum, and distal colon, but not proximal colon; rectal cancer risk was also higher among those who switched to or concurrently used NNTPs. Compared with exclusive CC use, however, all other smoking-status groups, including never smoking, former smoking, exclusive NNTP use, switching to NNTPs, and concurrent use, had lower colorectal cancer risk, though the magnitude varied by subsite. These findings indicate that the association between smoking status and colorectal cancer risk depends on both the comparison group and cancer subsite, underscoring the need for long-term studies to clarify the effects of NNTP use on colorectal cancer risk.