Smoking and colorectal cancer: A pooled analysis of 10 population‐based cohort studies in Japan. Issue 3 (25th August 2020)

• Record Type: Journal Article
• Authors: Akter, Shamima; Islam, Zobida; Mizoue, Tetsuya; Sawada, Norie; Ihira, Hikaru; Tsugane, Shoichiro; Koyanagi, Yuriko N.; Ito, Hidemi; Wang, Chaochen; Tamakoshi, Akiko; Wada, Keiko; Nagata, Chisato; Tanaka, Kenta; Kitamura, Yuri; Utada, Mai; Ozasa, Kotaro; Sugawara, Yumi; Tsuji, Ichiro; Shimazu, Taichi; Matsuo, Keitaro; Naito, Mariko; Tanaka, Keitaro; Inoue, Manami
• Is Part Of: International journal of cancer. Volume 148:Issue 3(2021)
• Page Start: 654
• Page End: 664
• Publication Date: 2020-08-25
• Subjects: colorectal cancer -- former smokers -- pooled analysis -- sites of colorectal cancer -- smoking; Cancer -- Periodicals; Cancer -- Prevention -- Periodicals; 616.994
• DOI: 10.1002/ijc.33248
• Languages: English
• ISSNs: 0020-7136

Abstract

Abstract: Smoking has been consistently associated with the risk of colorectal cancer (CRC) in Western populations; however, evidence is limited and inconsistent in Asian people. To assess the association of smoking status, smoking intensity and smoking cessation with colorectal risk in the Japanese population, we performed a pooled analysis of 10 population‐based cohort studies. Study‐specific hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated using Cox's proportional hazards model and then pooled using a random‐effects model. Among 363 409 participants followed up for 2 666 004 person‐years, 9232 incident CRCs were identified. In men, compared with never smokers, ever smokers showed higher risk of CRC. The HRs (95% CI) were 1.19 (1.10‐1.29) for CRC, 1.19 (1.09‐1.30) for colon cancer, 1.28 (1.13‐1.46) for distal colon cancer and 1.21 (1.07‐1.36) for rectal cancer. Smoking was associated with risk of CRC in a dose‐response manner. In women, compared with never smokers, ever smokers showed increased risk of distal colon cancer (1.47 [1.19‐1.82]). There was no evidence of a significant gender difference in the association of smoking and CRC risk. Our results confirm that smoking is associated with an increased risk of CRC, both overall and subsites, in Japanese men and distal colon cancer in Japanese women. Abstract : What's new? Colorectal cancer (CRC) has been included in lists of tobacco‐related cancers. However, this inclusion has been based on data from Western populations. Studies of Asian populations have yielded conflicting results. In the current study, the authors conducted a pooled analysis of 10 cohort studies in Japan. They found that smoking is also associated with an increased risk of CRC (both overall and at subsites) in Japanese men, and of distal colon cancer in Japanese women. This increase in risk was dose dependent.