in the cancer research field , vitamin d has emerged as the most prolific topic in the last decade with work connecting it with risk reduction in various epithelial cancers . aside from calcium homeostasis , vitamin d exerts a wide range of immunogenic and antiproliferative activities in the body .
of particular interest to the oncologists is the reduced incidence of breast , colon , and prostate cancers with higher sun exposure , higher intake , or higher serum levels of vitamin d. vitamin d exerts its antiproliferative effect by binding to vitamin d receptor ( vdr ) found in various tissues and cells of the body .
several human genes contain vitamin d response elements ( specific dna sequences ) that encode for proteins important in regulation of cell proliferation , differentiation , apoptosis , and angiogenesis .
when the serum vitamin d levels are suboptimal these activities are impaired and as a result enhanced cellular growth , neoangiogensis , and cancer development takes place .
the breast cells have vdrs in their nuclei and it is postulated that polymorphism of genes for these vdrs results in increased risk for breast cancer .
vitamin d from both diet and sun exposure is metabolized in the liver to 25-hydroxy vitamin d ( 25(oh)2d ) and then further hydroxylated by 1 alpha hydroxylase enzyme in kidneys and other tissues like breast cells to 1,25- dihydroxy vitamin d ( 1,25 ( oh)2d ) , the most biologically active form and the natural ligand for vdr .
serum concentration of 25(oh)2d are more sensitive to exogenous sources ( dietary and supplemental intake ) and endogenous production ( through synthesis in the skin ) of vitamin d and have a long half - life of 3 weeks and is the predominant form of vitamin d in plasma and the major storage form ; hence the circulating 25(oh)2d is the best indicator of vitamin d status of the body .
serum 25(oh)2d concentrations as well as treatment with vitamin d supplementation are significant independent predictors of breast cancer risk .
women with serum levels of 25(oh)2d more than 50 ng / ml had a 50% lower risk of breast cancer compared to those with serum values less than 30 ng / ml in various studies from the developing world .
it has been documented that consumption of oral calcium and serum levels of vitamin d are associated with reduced risk of breast cancer in premenopausal women but the results were not statistically significantly in postmenopausal women .
there are data showing that locally advanced breast cancer patients have more severe vitamin d deficiency than those with early stage disease .
low serum levels of vitamin d are common at breast cancer diagnosis and are associated with a poorer prognosis in terms of overall survival and distant disease free survival particularly in postmenopausal females . in another group of breast cancer patients
it was found that 94% women with serum levels of vitamin d less than 20 ng / ml were likely to develop metastases and 73% were likely to die of advance disease .
vitamin d deficiency is associated with secondary hyperparathyroidism which results in increased bone resorption , release of calcium from bones , and may precipitate or exacerbate osteoprosis with consequent ill effects on bone mineral density ( bmd )
. there has been significant documentation of osteopenia and osteoprosis in breast cancer patients primarily due to early menopause and vitamin d deficiency and later amplified by chemotherapy and endocrine therapy particularly the aromatase inhibitors .
thus breast cancer patients must undergo a baseline metabolic bone evaluation with serum vitamin d levels and bone mineral densitometry .
the aim of the study was to determine serum levels of 25-(oh)2d in pakistani breast cancer patients at the time of presentation , to assess its risk association with grade and stage of the tumor and to evaluate the bone density in breast cancer patients .
the study was approved by the scientific research committee and institutional review board at shaukat khanum memorial cancer hospital and research centre , lahore .
all newly diagnosed breast cancer patients who presented to the medical oncology department were recruited into the study as 
cases  after informed consent over a period of 6 months from november 2010 till may 2011 .
age - matched healthy females who accompanied the nonbreast cancer patients to hospital were recruited as the  control group . 
the socio - demographics were documented by direct questioning on to the proforma for the whole study population .
postmenopausal status of females was defined as last menstrual bleeding at least 12 months before the date of interview or a history of bilateral oophorectomy .
the histopathological diagnosis of breast cancer , grade , stage of the tumor , and hormone receptor status ( estrogen receptor - er , progesterone receptor  pr , and her2neu ) was recorded from the pathology reports of breast cancer patients .
serum 25-(oh)2d levels were studied by the elisa technique on the blood samples drawn of the study population at their initial presentation and the values were documented in ng / ml .
vitamin d deficiency was considered at serum level less than 20 ng / ml , suboptimal vitamin d levels were considered between 20 and 39 ng / ml and optimal levels were more than 40 ng / ml .
bone mineral density was calculated according to the who criteria from ct bone density scan of the breast cancer patients .
the demographic variables and the descriptive measures in cases and controls were presented in frequency and percentages .
relation of vitamin d deficiency with grades , stages , histology , and receptor status of tumor was determined by using the chi - square test .
comparison of vitamin d levels among various histopathological parameters of tumor was done by using one - way anova .
comparison of vitamin d levels between pre- and postmenopausal status was done by using a t - test .
the association of vitamin d status with bmd in cases and the serum vitamin d levels among the cases and controls was calculated by using the chi - square .
the demographic variables and the descriptive measures in cases and controls were presented in frequency and percentages .
relation of vitamin d deficiency with grades , stages , histology , and receptor status of tumor was determined by using the chi - square test .
comparison of vitamin d levels among various histopathological parameters of tumor was done by using one - way anova .
comparison of vitamin d levels between pre- and postmenopausal status was done by using a t - test .
the association of vitamin d status with bmd in cases and the serum vitamin d levels among the cases and controls was calculated by using the chi - square .
the mean age of cases was 47.5th 9.8 years and for the control group was 46.2th + 2.6 years .
there were 46.7% premenopausal females and 53.3 % postmenopausal females among the breast cancer population .
age , marital status , menopausal , residential area , and parda observing status had almost similar distribution among cases and controls .
a total of 70% of the cases were multiparous and the 50% of the healthy controls had more than three children . regarding the occupational history ,
92% of the cases were house wives while 33% of the controls were office workers .
the mean serum vitamin d level in the breast cancer patient was 9.3 ng / ml and in the control group was 14.9 ng / ml and the p value calculated was < 0.001 .
vitamin d deficiency was seen in 95.6% ( 86 ) breast cancer patients while 77% ( 69 ) of the control group were deficient , the p value was < 0.001 .
suboptimal levels of vitamin d were seen in 4.4% ( 4 ) of the cases and 18.9% ( 17 ) control group , p value < 0.001 .
none of the breast cancer patients had an optimal vitamin d level , while four patients in the control group had normal serum levels [ table 1 ] .
serum vitamin d level in cases and controls among the breast cancer patients the tumor characteristics ( histology , grade , stage , and receptor status ) did not show any significant associations with serum levels of vitamin d. on analysis of the individual grade of breast cancer with serum vitamin d levels , it was seen that grade iii tumors had a mean vitamin d level of 8.6 ng / ml + sd 3.44 , while similar low levels ( mean 8.5 ng / ml + sd 3.54 ) were also seen in grade i tumors .
grade ii breast cancer patients had a mean serum vitamin d level of 10.28 + sd 6.23 .
serum vitamin d levels were found to be lower ( mean 8.49 ng / ml and 9.86 ng / ml ) in stage iii and iv breast cancer respectively and 12.75 ng / ml in stage i disease but the p value was 0.247 [ table 2 ] .
association of serum vitamin d level with stage of breast cancer on comparing serum vitamin d levels with receptor status , patients with her2neu over expression had a mean vitamin d level of 8.28 ng / ml + sd 2.3 , patients with triple negative tumors had mean serum vitamin d levels 10.3 ng / ml + sd 4.65 , triple positive and er positive / her2 negative had 9.04 ng / ml + sd 3.97 and 9.06 ng / ml + sd 5.5 respectively .
the calculated p value was 0.681 . according to the menopausal state of breast cancer patients , premenopausal females had a mean serum vitamin d level of 10.5 ng / ml and postmenopausal females
had a mean value of 13.5 ng / ml . the p value by t - test was 0.015 [ table 3 ] .
distribution of serum vitamin d level according to menopausal status of breast cancer patients on estimation of bone mineral density ( bmd ) in vitamin d deficient breast cancer patients , 36 patients had normal bone density , 34 patients had osteopenia , and 16 patients had osteoporosis .
four patients had suboptimal vitamin d levels , out of which 2 had osteopenia and 1 had normal bone density and osteoporosis each .
low bmd ( osteopenia and osteoprosis ) among the postmenopausal breast cancer patients was found in 35/45 ( 73% ) females while only 18/42 ( 43% ) premenopausal females had low bmd ( osteopenia only ) with a p value of < 0.001 [ table 4 ] .
low levels of vitamin d are the norm rather than an exception in south east asia .
the prevalence of vitamin d deficiency in healthy asymptomatic people is reported in the range of 70 - 97% in pakistan and this is more common in the urban population .
studies from united states report 50 - 74% vitamin d deficiency in newly diagnosed premenopausal breast cancer patients . in our study
we found that 95.6% breast cancer females and 77% healthy females were vitamin d deficient .
our results for the healthy control group lie within the range reported in the pakistani literature .
serum levels of vitamin d in breast cancer patients were significantly lower than in non breast cancer pakistani women .
hence , the association between breast cancer risk and serum levels of vitamin d parallels other studies from the developed world .
our two groups of population were comparable in age , menopausal state , residential area ( rural vs. urban ) and parda observation characteristics .
the study consisted of middle - aged females with equal distribution of pre- and postmenopausal females .
multiparty was high in the breast cancer women and we expect that the deficiency of vitamin d was compounded by the suboptimal nutrition in this group .
ninety - two percent of the breast cancer females were housewives looking after their children and homes and expected to have minimal sun exposure . in the control group 66% females were housewives while 34% were office going ; thus assuming that the healthy subjects did get some solar exposure as they went out of the house , in this study we did not categorically ask about the direct amount of sun exposure .
none of the females we interviewed was a field worker , expected to have maximum sun exposure .
more than half of the study population in both groups was above the expected normal bmi .
twenty - eight ( 31% ) females in the breast cancer group versus eighteen ( 20% ) females in the healthy group were obese ( bmi > 30 ) , revealing a small but sinister causal link of low vitamin d levels with high bmi in breast cancer patients .
lower serum levels of vitamin d have been associated with obesity and lower physical activity in various epidemiological studies .
serum levels of vitamin d did not correlate inversely with the advance stage and grade of breast cancer in our study .
regarding the receptor types of breast cancer ( luminal types a and b , triple negative or her2 neu over - expressed ) all had similar deficient vitamin d levels and there was no difference of statistical importance .
recently kim et al . , from korea reported poorer outcomes of vitamin d deficient patients with luminal type breast cancer .
also there are data suggesting that triple negative breast cancer patients have the highest percentage of vitamin d deficiency .
studies with both pre- and postmenopausal female populations have shown high prevalence of vitamin d deficiency despite supplementation .
premenopausal females had slightly more low mean serum levels of vitamin d compared to the postmenopausal females and the results yielded minimum significance .
recruited 1295 postmenopausal females and showed that low levels of vitamin d correlated with increased risk of distant recurrence and poor overall survival .
examination of bone mineral density in breast cancer patients revealed that osteopenia and osteoporosis was common in postmenopausal female , as expected .
more than half of vitamin d deficient breast cancer females had low bmd ( osteopenia or osteoporosis ) but the data did not show statistical significance and hence bmd can not be considered as an indirect marker for evidence of vitamin d status for an individual .
vitamin d concentration may be a risk and/or a valuable prognostic factor in breast cancer patients on the basis of various studies but data from large randomized trials are still sparse .
the optimal circulating level of 25(oh)2d for reducing breast cancer risk or reducing the risk of recurrence of breast cancer has yet to be defined .
it is also known that there are ethnic and racial variations in serum vitamin d levels .
asians have low exposure to sunlight , there is high prevalence of various malabsorption syndromes , and use of vitamin d supplementation is rare .
few epidemiological efforts have investigated the association between vitamin d concentration and breast cancer risk in asian women . to our knowledge
ours is the first study from pakistan to assess the association between breast cancer and serum vitamin d levels . the relatively small size of the study population limited our ability to detect statistically significant trends of vitamin d deficiency with respect to histopathological characteristics of the breast cancer .
vitamin d deficiency is rampant in pakistan and also serum 25(oh)2d levels are reflective of a recent and not life time vitamin d intake ; hence one single measurement of vitamin d levels in our study may not be reflective of long term exposure .
the relevant time period during which 25(oh)2d levels may affect breast cancer occurrence or survival is currently unknown . regardless of whether vitamin d helps prevent cancer development or its recurrence
, the high frequency of vitamin d deficiency in the pakistani population with its adverse impact on bone health and further intolerance to various systemic cancer treatments makes it important for the oncologists to recognize , treat , and prevent vitamin d deficiency .
as more studies confirm similar results , dietary vitamin d and casual sunlight exposure will be among the modifiable risk factors for breast cancer .
 aim : the aim was to determine serum vitamin d levels in breast cancer patients and to assess its risk association with grade and stage of the tumor.materials and methods : ninety breast cancer patients and equal number of age - matched healthy females were recruited into the study by consecutive sampling over a period of 6 months for this case control study . 
 serum 25(oh)2d levels and ct bone mineral density was done.results:the mean age was 461.5 years . 
 age , marital status , menopausal , residential area , parda observing status , and body mass index were similar in distribution among cases and controls . 
 the mean serum vitamin d level in the breast cancer patients was 9.3 ng / ml and in the control group was 14.9 ng / ml ( p value < 0.001 ) . 
 vitamin d deficiency was seen in 95.6% ( 86 ) breast cancer patients and in 77% ( 69 ) of the control group ( p value < 0.001 ) . among the breast cancer patients the tumor characteristics ( histology , grade , stage , and receptor status ) did not show any significant associations with serum levels of vitamin d. premenopausal breast cancer females had a mean serum vitamin d level of 10.5 ng / ml and postmenopausal females had a mean value of 13.5 ng / ml ( p value 0.015 ) . 
 low bmd did not correlate significantly with vitamin d deficiency ( p value 0.787).conclusion : invariably almost all patients with breast cancer were vitamin d deficient . 
 tumor characteristics did not show any significant associations with serum levels of vitamin d. bone mineral density did not correlate significantly with vitamin d deficiency . 
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