|LETTER TO THE EDITOR
|Year : 2021 | Volume
| Issue : 4 | Page : 778-779
Diet and colorectal cancers
Mayank Tripathi, Durgatosh Pandey, Saumya Chopra
Department of Surgical Oncology, MPMMCC and HBCH, Varanasi, Uttar Pradesh, India
|Date of Submission||29-Oct-2021|
|Date of Decision||06-Nov-2021|
|Date of Acceptance||08-Nov-2021|
|Date of Web Publication||29-Dec-2021|
Department of Surgical Oncology, MPMMCC and HBCH, Varanasi, Uttar Pradesh
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Tripathi M, Pandey D, Chopra S. Diet and colorectal cancers. Cancer Res Stat Treat 2021;4:778-9
We read the article title “Dietary risk factors for colorectal cancer: A hospital-based case–control study,” by Zargar et al. with keen interest. We must congratulate the authors on conducting such a study in the Indian setting, considering that India has vast cultural diversity and varying dietary practices. The study methodology was well constructed and could guide future studies in this direction, including modifications in the already validated questionnaires. However, there are certain conceptual flaws that need to be considered while interpreting the results of this study. In a case control study on diet, participants (both cases and controls) are affected by a recall bias. Participants who are already diagnosed with cancer tend to overestimate the consumption of “unhealthy foods.” Also, they tend to change their dietary habits once the symptoms of cancer begin to appear or after their first visit to a cancer clinic. Giovannucci et al. have documented the differential reporting of fat intake before and after the diagnosis of cancer. Hence a strong possibility of recall bias poses a threat to the observed association in this study. Another issue with such case control studies is the increased participation of health-conscious individuals as controls, which may not accurately reflect the dietary habits of the general population. We are also curious if the authors considered the socioeconomic status and literacy rates while selecting the cases and controls, which are obvious confounding factors in a country like India.
We would also like to know how the controls were designated as “healthy” and whether they underwent colonoscopy or sigmoidoscopy before inclusion. As per the study methodology, siblings and healthy attendants were included in the study as controls, and we wonder if this could be another confounding factor, as in India, members of a family, by and large, share similar food habits with little variation.
Lastly, the inclusion of a small number of participants limited the power of the study.
The etiology of colorectal cancer is multifactorial, with an interplay between both genetic and environmental factors. Evidence suggests that modifiable lifestyle factors, including obesity, diet, and physical activity, play an important role in the occurrence of colorectal cancers., In a review and meta-analyses, Veettil et al. reported convincing evidence for an association between lower colorectal cancer risk and higher intake of dietary fiber, calcium, and yogurt. They also reported that there was a direct relationship between the intake of alcohol and red meat and the occurrence of colorectal cancer. India is witnessing a rise in colorectal cancer incidence with an increasing number of patients presenting at a younger age compared to the western population. From 2004 to 2014, colorectal cancer incidence increased by 20%, and thus, it is prudent to conduct well planned cohort studies to identify modifiable risk factors for effective prevention and control of colorectal cancers.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
| References|| |
Zargar T, Kumar D, Sahni B, Shoket N, Bala K, Angurana S. Dietary risk factors for colorectal cancer: A hospital-based case-control study. Cancer Res Stat Treat 2021;4:479-85. [Full text]
Giovannucci E, Stampfer MJ, Colditz GA, Manson JE, Rosner BA, Longnecker M, et al.
A comparison of prospective and retrospective assessments of diet in the study of breast cancer. Am J Epidemiol 1993;137:502-11.
Chan AT, Giovannucci EL. Primary prevention of colorectal cancer. Gastroenterology 2010;138:2029-43.e10.
Tahiliani HT, Purohit AP, Desai SC, Jarwani PB. Retrospective analysis of histopathological spectrum of premalignant and malignant colorectal lesions. Cancer Res Stat Treat 2021;4:472-8. [Full text]
Veettil SK, Wong TY, Loo YS, Playdon MC, Lai NM, Giovannucci EL, et al.
Role of diet in colorectal cancer incidence: Umbrella review of meta-analyses of prospective observational studies. JAMA Netw Open 2021;4:e2037341.
Thomas VM, Baby B, Wang K, Lei F, Chen Q, Huang B, et al
. Trends in colorectal cancer incidence in India. J Clin Oncol 2020;38 Suppl 15:e16084.