New evidence for protective role of Vitamin D in breast cancer in Pakistani women

A new study by cancer researchers from the University of Adelaide, and Aga Khan University in Karachi, Pakistan supports scientific literature that deficient levels of serum vitamin D may contribute to breast cancer and its correction may play a role in protection against breast cancer.

Published in the journal PLOS ONE, the findings yield important insights into whether boosting Vitamin D levels can help prevent breast cancer in Pakistan, a country faced with highest incidence of breast cancer in South Asia and limited health budget.

Over the past few years, the potential protective role of vitamin D in breast cancer has been the subject of considerable interest with mixed results. Laboratory and genetic studies demonstrate promising anticancer effects of vitamin D. Limited evidence, from human studies on breast cancer and vitamin D studies – mostly in Western populations – suggests a protective role of Vitamin D in breast cancer. Here, the role of vitamin D in breast cancer was examined among the understudied Pakistani population.

For this purpose, a multicenter case control study was conducted in two large hospitals of Karachi. Data was collected from 400 breast cancer cases and 1194 cancer-free women, on sociodemographic status, vitamin D supplementation, past medical and reproductive history, family history of breast cancer and sun exposure history, and blood was collected to measure serum vitamin D level.

The study results showed that women with vitamin D deficiency were at higher risk of breast cancer as compared to women with adequate vitamin D level. Another finding was that vitamin D supplementation was associated with decreased risk of breast cancer.

The findings held true even after the analysis results were adjusted for common risk factors for breast cancer, such as the participant’s age at first live birth, number of children, age at menarche and menopause, body mass index (BMI), breast feeding duration, and mammographic breast density.  A surprising finding in the study was that there was no association of common risk factors with breast cancer among the study participants.  

“Finding of significant association between vitamin D deficiency and breast cancer is important as the prevalence of vitamin D deficiency and breast cancer are both high among Pakistani women,” says Dr Uzma Shamsi, University of Adelaide PhD graduate and the Principal Investigator of the study. She is now Assistant Professor at Aga Khan University.

“In Pakistani women raising and maintaining serum vitamin D level at the population level can be achieved through public awareness campaigns, through lifestyle changes that promote sensible sun exposure, consumption of foods containing vitamin D and foods fortified with vitamin D, and use of vitamin D supplements.

“Considering the high prevalence of vitamin D deficiency among women, more funding should be diverted for such cost effective interventions.” 

While the findings are encouraging and help address important issue related to vitamin D and breast cancer, researchers are cautious about its conclusion and interpretation.

‘‘However, it is not possible to prove the causal relationship between vitamin D and breast cancer due to the limitation of the current case control study design,” says Dr Shamsi. “Further high quality cohort and molecular studies are needed to draw firmer conclusions and clarify this association in a dose-response relationship.

“More recent advances in laboratory sciences, and measurement of vitamin D levels directly in the breast tissue will help improve our understanding of the causal relationship between vitamin D and breast cancer for prevention strategies.”

The study was a collaboration between University of Adelaide, Aga Khan University and the Karachi Institute of Radiation and Nuclear Medicine Cancer Hospital (KIRAN).

Co-authors were Dr David Callen and Dr Tiffany Gill from University of Adelaide, Australia, Dr Romaina Iqbal, Dr Shaista Khan, Mr. Iqbal Azam, and Dr Aysha Habib Khan from Aga Khan University, and Dr Mohammad Hanif  and Dr Amir Maqbool from KIRAN.