Cigarette smoking, alcohol consumption, and risk of colorectal cancer in South Korea: A case-control study

Highlights

• The associations among smoking, alcohol consumption, and colorectal cancer have not been well established for women.

• The duration and amount of smoking, and alcohol consumption amount were associated with colorectal cancer risk in both men and women.

• Women showed a greater risk of colorectal cancer with lower amount and duration of smoking and less alcohol consumption.

Abstract

The current case-control study comprehensively evaluated the status, quantity, and duration of smoking and alcohol drinking for both men and women, considering the subsites of colorectal cancer. A total of 925 colorectal cancer cases and 2775 controls were included in the analysis. Odds ratios (OR) and 95% confidence intervals (CI) were computed by logistic regression models adjusting for potential confounders. In men, the risk of colorectal cancer significantly increased for heavy smokers who smoked ≥40 pack-years (OR 1.74, 95% CI 1.22–2.50), ≥40 years (OR 1.50, 95% CI 1.05–2.16), or ≥40 cigarettes/day (OR 1.92, 95% CI 1.04–3.54). Men showed a significant increase in risk, especially for rectal cancer with an increasing amount or duration of smoking. In women, distal colon cancer risk increased in smokers who smoked ≥20 years (OR 3.21, 95% CI 1.27–8.14) or ≥20 cigarettes/day (OR 4.75, 95% CI 1.09–20.57). Additionally, female smokers who smoked ≥20 cigarettes/day had an increased risk of rectal cancer (OR 6.46, 95% CI 1.64–25.46). Regarding the association of cigarettes smoked per day and the risk of rectal cancer, there was no significant difference between men and women (gender interaction p value = 0.14). Compared with never-drinkers, those who consumed alcohol at ≥40 g/day in men and ≥20 g/day in women had an OR of 2.39 (95% CI 1.68–3.41) and 3.52 (95% CI 1.56–7.96), respectively. The effect of daily alcohol consumption (g of ethanol/day) on cancer risk was not significantly different among subsites. Association of alcohol consumption quantity (g of ethanol/day) and the risk of proximal and distal colon cancer were stronger in women than in men (gender interaction p value < 0.01). There was no significant interaction in the multiplicative level when alcohol consumption and cigarette smoking were combined. The duration and amount of smoking as well as the amount of alcohol consumption were associated with an elevated risk of colorectal cancer in both men and women.

Introduction

The age-standardized incidence rate of colorectal cancer per 100,000 people increased from 26.2 to 40.2 in men and from 16.4 to 22.2 in women between 1999 and 2015 in South Korea (Jung, Won, Kong, & Lee, 2018). Although the incidence of colorectal cancer decreased slightly after 2012, colorectal cancer has been the third most common cancer in South Korea since 2011 (Jung et al., 2018).

Numerous cohort studies and meta-analyses have established the association between colorectal cancer and risk factors such as cigarette smoking and alcohol consumption (Ahn et al., 2007, Botteri et al., 2008, Cheng et al., 2015, Goldbohm et al., 1994, Liang et al., 2009, Limsui et al., 2010, Stürmer et al., 2000). The International Agency for Research on Cancer (IARC) concluded that smoking and alcohol consumption are ‘carcinogenic agents with sufficient evidence in humans’ (Cogliano et al., 2011).

While several Korean cohort studies showed an elevated risk of colorectal cancer in ex-smokers (Jee et al., 2004, Kim et al., 2006, Shin et al., 2011, Yun et al., 2005), a dose-response relationship between smoking and colorectal cancer has not been clearly established (Cho et al., 2015, Kim et al., 2006, Yun et al., 2005). A case-control study showed a significantly increased odds ratio for colorectal cancer in heavy drinkers who drank more than 30 g ethanol/day (Kim et al., 2004). Two cohort studies showed a dose-response relationship of alcohol consumption and colorectal cancer in men (Cho et al., 2015, Shin et al., 2011). However, there has not been any study that convincingly demonstrated a significant association among smoking, alcohol consumption, and colorectal cancer in women. The object of this study was to investigate the effects of status, quantity, and duration of smoking and alcohol consumption on colorectal cancer risk by anatomical subsite and sex.