|LETTER TO EDITOR
|Year : 2020 | Volume
| Issue : 2 | Page : 369-370
Causal association of Vitamin D deficiency with cancer: More research needed
Uzma Shamsi1, Shaheryar Usman2
1 School of Medicine, The University of Adelaide, Adelaide, Australia
2 Department of Community Health Sciences, Aga Khan University, Karachi, Pakistan
|Date of Submission||18-Mar-2020|
|Date of Acceptance||22-Mar-2020|
|Date of Web Publication||19-Jun-2020|
School of Medicine, The University of Adelaide, Adelaide
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Shamsi U, Usman S. Causal association of Vitamin D deficiency with cancer: More research needed. Cancer Res Stat Treat 2020;3:369-70
We read the article written by Pandey et al. with interest. The study findings supported the hypothesis of an association of low Vitamin D levels with upper gastrointestinal, breast, colorectal, and ovarian cancers. It is an important study when there is high prevalence of Vitamin D deficiency globally, with ongoing debate and research being conducted on the relationship between cancer and Vitamin D concentrations. A number of cell line experiments, animal studies, and ecological studies support the role of Vitamin D as an anticancer agent.,, However, the results from observational studies such as case–control, cohort, and nested case–control studies differ in reporting an association of Vitamin D with cancer which is more frequently reported in case–control than cohort studies. Cohort studies investigating the role of Vitamin D in breast cancer have reported mixed results with no association as well as protective association. Lack of temporality and the chance of reverse causation are inherent in case–control studies. In most case–control studies, blood collection for an assay of Vitamin D concentrations is after cancer diagnosis, due to which it is possible that the presence of cancer cells and catalytic enzymes affect the Vitamin D levels. On the other hand, the problem with cohort studies is that the duration of follow-up is variable in different studies and may not be sufficient to observe any long-term effects of blood concentrations of Vitamin D and cancer risk. Besides, the serum concentrations of Vitamin D also keep changing with the season and the exact timing of the blood assay to link with cancer are also debatable.
Overall, it was a well-conducted cross-sectional study which is a cost-effective and time-efficient study design at a time when there is a dearth of studies evaluating the relationship between Vitamin D and different cancers in the Asian population. The study findings are supported by a review based on a number of experimental and clinical observations  and a similar study in Pennsylvania, USA. Although the study is interesting, due to only descriptive analysis and lack of analytical research, the clinical significance of Vitamin D deficiency in cancer and the role of Vitamin D supplementation in cancer prevention remain unanswered. The study does not scientifically show a causal relationship between the lack of Vitamin D and cancer. A comparison group of controls without cancer would have given better evidence of association of Vitamin D deficiency with cancers after adjustment of important risk factors for cancer, e.g., family history of cancer, socioeconomic status, and body mass index, and would have strengthened the evidence of Vitamin D deficiency in cancers. In the study, cancer patients may be more likely to have Vitamin D deficiency for reasons other than cancer such as reduced sun exposure or nutritional changes. As mentioned in the accompanying editorial, the investigators did not look at the comorbidities, complete nutritional status of the patient, body mass index, and its correlation with Vitamin D levels, and the patients who were offered intervention were not followed up for outcomes. In oncology practice, it is still difficult to make recommendations to individual patients for Vitamin D supplementation due to lack of evidence of the benefits of Vitamin D supplementation in cancer patients without other side effects, such as hypercalcemia. Finally, in title, the use of “prevalence of Vitamin D deficiency” is a little misleading as it is a hospital-based study where one cannot calculate the prevalence but the frequency only.
More funding and research are needed to confirm any role of Vitamin D as a cost-effective anticancer agent and to study its dose–response relationship with different cancers. Future studies are needed with a larger sample size and to include other biomarkers such as 1,25(OH) D, parathyroid hormone, calcium, magnesium, and phosphate levels to comprehend the complex metabolism of Vitamin D deficiency in cancer.
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Conflicts of interest
There are no conflicts of interest.
| References|| |
Pandey A, Singh A, Singh S. Prevalence of Vitamin D deficiency in treatment-naive individual consecutive cancer patients. Cancer Res Stat Treat 2020;3:25-31. [Full text]
Krishnan AV, Trump DL, Johnson CS, Feldman D. The role of Vitamin D in cancer prevention and treatment. Endocrinol Metab Clin North Am 2010;39:401-18.
Ness RA, Miller DD, Li W. The role of Vitamin D in cancer prevention. Chin J Nat Med 2015;13:481-97.
AlMatar M, AlMandeal H, Makky EA, Kayar B, Yarar E, Var I, et al
. The Physiological/pathophysiological significance of Vitamin D in cancer, cardiovascular disorders and beyond. Curr Drug Metab 2017;18:207-24.
Giammanco M, Di Majo D, La Guardia M, Aiello S, Crescimannno M, Flandina C, et al
. Vitamin D in cancer chemoprevention. Pharm Biol 2015;53:1399-434.
Churilla TM, Brereton HD, Klem M, Peters CA. Vitamin D deficiency is widespread in cancer patients and correlates with advanced stage disease: A community oncology experience. Nutr Cancer 2012;64:521-5.
Batra U, Sharma M. Association of Vitamin D with cancer – Catch me if you can! Cancer Res Stat Treat 2020;3:78-80.
Goodwin PJ. Vitamin D in cancer patients: Above all, do no harm. J Clin Oncol 2009;27:2117-9.