Smoking a Risk Factor for CRC in Black African Patients

African patients were found to have an association between smoking and colorectal cancer (CRC), with patients who smoked having higher odds of CRC overall, according to a study published in Journal of Public Health in Africa.¹ The combination of smoking and alcohol was also found to have an association with CRC.

CRC is a leading cause of cancer deaths worldwide, with its prevalence making it one of the most common cancers.² There have been several risk factors found to be associated with CRC, including red meat intake, processed meat consumption, physical inactivity, and being overweight alongside smoking and alcohol intake. The association between smoking and alcohol consumption with CRC has been underreported in patients from Africa. This study aimed to assess the association of smoking and alcohol with CRC in patients who were Black Africans.¹

Black African patients had a higher risk of colorectal cancer if they smoked | Image credit: Dr_Microbe - stock.adobe.com

All patients included were those who attended the Steve Biko Academic Hospital for the gastrointestinal (GIT) clinic between January 2016 and December 2018. All Black African patients were included if they were 18 years or older and had received a colonoscopy to evaluate suspected CRC. Patients who were not Black African, had not undergone a colonoscopy, and were younger than 18 years were excluded from the study. Demographic characteristics and medical history were included.

The primary exposures were smoking and alcohol consumption, with a smoker being defined as someone who had smoked either a cigar, a pipe, or a cigarette before their colonoscopy. Patients who consumed alcohol prior to their colonoscopy were defined as those who partook in alcohol consumption. History of smoking and alcohol consumption were also included by the primary physician.

There were 330 patients included in the study, of whom 110 were cases, and 220 were controls. There were slightly more women included in the study overall (52%). A total of 66% of the patients who received a colonoscopy were aged 50 years or older compared with the remaining patients who were aged 18 to 50 years. The most common symptom of CRC was weight loss (49%), with rectal bleeding (33%), iron deficiency (26%), bowel changes (26%), and positive fecal occult blood (25%) also presenting as common signs of CRC.

Most of the cases of CRC were in the colon (65.5%) compared with the rectum, and 48.2% of the cases were diagnosed at stage I or II. Patients older than 50 years had an OR of 3.51 when evaluating the likelihood of CRC compared with patients aged 18 to 50 years. Men had an OR of 3.469 for contracting CRC compared with women, and patients with a family history of CRC had an OR of 9.87 for CRC. Patients who smoked had an OR of 3.41 for diagnosis of CRC, whereas alcohol consumption was protective with an OR of 0.29. Patients who did not consume alcohol had an OR of 3.45 for contracting CRC.

When a logistic regression was used to evaluate the relationships between smoking, alcohol consumption, and CRC, significant risk factors were found to be family history (OR, 12.46; 95% CI, 3.35-46.32), smoking (OR, 1.80; 95% CI, 1.00-3.21), and being aged older than 50 years (OR, 3.74; 95% CI, 2.00-7.09). Alcohol consumption was protective (OR, 0.21; 95% CI, 0.09-0.50).

There were some limitations to this study. All of the data were retrieved from a single center. The amount of smoking or alcohol consumption done by each patient was not recorded and could have affected the likelihood of CRC. The questions about smoking and alcohol consumption were asked in an unknown way and could be subject to recall bias. It is possible that answers could have been recorded incorrectly. The retrospective design can only confirm correlation rather than causation. Selection bias is also possible because all patients came from tertiary hospitals.

The researchers concluded that both smoking alone and smoking with alcohol consumption were indicative of higher rates of CRC in Black Africans, whereas a protective effect was noted for alcohol consumption alone. Larger studies will be needed to assess the full extent of the protective effects of alcohol consumption.

References

1. Kgomo MK, Zingoni RL, Becker PJ. The association of smoking and alcohol in colorectal cancer in black patients – case-control study. J Public Health Africa. 2024;15(1):532. doi:10.4102/jphia.v15i1.532
2. Colorectal cancer: key facts. World Health Organization. July 11, 2023. Accessed November 11, 2024. https://www.who.int/news-room/fact-sheets/detail/colorectal-cancer