Cigarette Pack-Years Linked to Recurrent Colorectal Neoplasia in IBD Patients


The first known dose-effect relationship study between colorectal neoplasia and smoking in patients with IBD strengthens the importance of achieving cessation.

Cigarette Pack-Years Linked to Recurrent Colorectal Neoplasia in IBD Patients

Anouk M. Wijnands, MD

Credit: LinkedIn

Cigarette smoking is associated with an increased risk of recurrent colorectal neoplasia among patients with irritable bowel disease (IBD), according to new data.1

In research from a team of Denmark investigators, increasing rates of pack-years among those who smoke cigarettes was positively linked a significantly greater risk of developing recurrent colorectal neoplasia, a precursor to colorectal cancer, among patients with established IBD. With what they believe to be the first study to interpret dose-effect relationships between colorectal neoplasia and smoking in patients with IBD, the investigators stressed their findings add to the significance of achieving cessation in at-risk patients.

Led by Anouk M. Wijnands, MD, of the University Medical Center of Utrecht, investigators sought to expand the understood link between smoking and related dose-effects on the development of colorectal neoplasia in patients with IBD. Previous research has established smoking as a risk factor for sporadic adenomas and colorectal cancer.2

“Prior studies, examining the effect of smoking on (advanced) colorectal neoplasia risk in patients with IBD, reported conflicting results,” investigators wrote. “These studies were mostly based on retrospective observational study designs prone to biases caused by, amongst others, lack of predefined outcomes or variables. Also, in few studies, the effect of smoking was investigated in a multivariable model and none reported on a dose-effect relationship.”

Investigators recruited patients with longstanding IBD from a colonoscopic surveillance program at one of the 4 participating centers from 2011 – 2017. Inclusion criteria entailed a diagnosis of colonic IBD for ≥8 years or any duration in case of concomitant primary sclerosing cholangitis (PSC) in patients aged 18 – 70 years old. Mean duration of follow-up was 5 years.

Wijnands and colleagues sought a primary outcome of occurrence of recurrent colorectal neoplasia events, with lesions assumed to be the same if found at the exact same location in a consecutive procedure.

The team’s assessment included 613 patients, of whom 37 were excluded for criteria. Among the 576 eligible patients, 316 (55%) were diagnosed with ulcerative colitis or IBD and 260 (45%) were diagnosed with Crohn’s disease. Approximately half (n = 289) of the patients were male; median patient age was 50 years old, with an IBD duration of 18 years.

Investigators reported 275 (48%) patients smoked or formerly smoked, with a median rate of 9 pack-years. Among patients with ulcerative colitis or IBD, 55% of patients with extensive disease were ever smokers; among patients with extensive Crohn’s disease, 62% were ever smokers.

The team conducted ≥1 follow-up with 501 participants without a history of colorectal neoplasia at study index. During the median 5 follow-up years, 105 (20.9%) patients experienced ≥1 neoplasia.

Though Wijnand and colleagues did not observe a significant association between ever smoking and recurrent neoplasia risk (adjusted hazard ratio [aHR], 1.04; 95% CI, 0.75 – 1.44), there was a significant correlation between increasing time smoking and recurrent neoplasia. Each increasing 10 pack-years was associated with a 17% increased risk of colorectal neoplasia among patients with IBD (aHR, 1.17; 95% CI, 1.03 – 1.32; P <.05).

Investigators did not interpret differing risk correlations based on IBD subtype.

“This dose-effect relationship underscores that smoking affects the risk of colorectal neoplasia in patients with IBD,” the team wrote. “These findings are in line with studies from the general population that report an association of pack-years with sporadic adenoma and colorectal cancer.”

Though the assessment was limited by the relatively short follow-up period and a smaller cohort, investigators concluded their data show a dose-effect relationship between smoking pack-years and recurrent neoplasia risk among patients with IBD.

“The suggestion of a dose-effect relationship provides additional impetus, next to other health outcomes, for patients to quit smoking,” the team wrote.


  1. Wijnands AM, Elias SG, Dekker E, et al. Smoking and colorectal neoplasia in patients with inflammatory bowel disease: Dose-effect relationship [published online ahead of print, 2023 Jul 28]. United European Gastroenterol J. 2023;10.1002/ueg2.12426. doi:10.1002/ueg2.12426
  2. Wijnands AM, de Jong ME, Lutgens M, Hoentjen F, Elias SG, Oldenburg B. Prognostic factors for advanced colorectal neoplasia in inflammatory bowel disease: systematic review and meta-analysis. Gastroenterology. 2021; 160(5): 1584– 98.
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