***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: BACKGROUND Vitamin D has potent anticancer properties , especially against digestive-system cancers . Many human studies have used geographic residence as a marker of solar ultraviolet B and hence vitamin D exposure . Here , we considered multiple determinants of vitamin D exposure ( dietary and supplementary vitamin D , skin pigmentation , adiposity , geographic residence , and leisure-time physical activity-to estimate sunlight exposure ) in relation to cancer risk in the Health Professionals Follow-Up Study . METHODS Among 1095 men of this cohort , we quantified the relation of these six determinants to plasma  25-hydroxy-vitamin D [ 25(OH)D ] level by use of a multiple linear regression model . We used results from the model to compute a predicted 25(OH)D level for each of 47,800 men in the cohort based on these characteristics . We then prospect ively examined this variable in relation to cancer risk with multivariable Cox proportional hazards models . RESULTS From 1986 through January 31 , 2000 , we documented 4286 incident cancers ( excluding organ-confined prostate cancer and nonmelanoma skin cancer ) and 2025 deaths from cancer . From multivariable models , an increment of 25 nmol/L in predicted 25(OH)D level was associated with a 17 % reduction in total cancer incidence ( multivariable relative risk [ RR ] = 0.83 , 95 % confidence interval [ CI ] = 0.74 to 0.92 ) , a 29 % reduction in total cancer mortality ( RR = 0.71 , 95 % CI = 0.60 to 0.83 ) , and a 45 % reduction in digestive-system cancer mortality ( RR = 0.55 , 95 % CI = 0.41 to 0.74 ) . The absolute annual rate of total cancer was 758 per 100,000 men in the bottom decile of predicted 25(OH)D and 674 per 100,000 men for the top decile ; these respective rates were 326 per 100,000 and 277 per 100,000 for total cancer mortality and 128 per 100,000 and 78 per 100,000 for digestive-system cancer mortality . Results were similar when we controlled further for body mass index or physical activity level . CONCLUSIONS Low levels of vitamin D may be associated with increased cancer incidence and mortality in men , particularly for digestive-system cancers . The vitamin D supplementation necessary to achieve a 25(OH)D increment of 25 nmol/L may be at least 1500 IU/day BACKGROUND Very low vitamin D levels have been noted in patients with a variety of autoimmune diseases . OBJECTIVE To determine whether low vitamin D levels are associated with autoimmunity in the setting of vitiligo vulgaris . METHODS A prospect i ve cohort study was conducted on 45 consecutive patients with vitiligo vulgaris .  25-Hydroxyvitamin D levels  were determined from sera collected at the time of study enrollment . Logistic regression analysis of the relationship of 25-hydroxyvitamin D levels to disease state was performed , including surface area , recent-onset vitiligo , Fitzpatrick skin type and ethnicity , dairy intake , and both personal and family history of autoimmunity . Multiple univariate and multivariate logistic regression models were developed to assess the interrelationship of these parameters . RESULTS 25-Hydroxyvitamin D levels were divided into 3 groups : 31.1 % were normal ( > 30 ng/mL ) , 55.6 % were insufficient ( < 30 ng/mL ) , and 13.3 % were very low ( < 15 ng/mL ) . Insufficient 25-hydroxyvitamin D levels were associated with increasing Fitzpatrick phototypes ( odds ratio [ OR ] = 1.76 , 95 % confidence interval [ CI ] = 1.12 - 2.77 ) . Very low 25-hydroxyvitamin D levels were associated with comorbid autoimmune illness ( OR = 10.00 , 95 % CI = 1.06 - 94.7 ) , but not with age , gender , race/ethnicity , family history of vitiligo or autoimmune disease , new-onset disease , or body surface area affected . None of the surveyed patients reported daily vitamin D intake of greater than 200 IU . LIMITATIONS This study consists of a small cohort that assesses point prevalence without assessing seasonal variation in vitamin D levels . CONCLUSIONS Very low 25-hydroxyvitamin D levels ( < 15 ng/mL ) appear to be a reasonable screening tool for the presence of comorbid autoimmunity . Furthermore , we demonstrate that Fitzpatrick phototype , rather than ethnicity , is specifically associated with 25-hydroxyvitamin D levels that are insufficient ( < 30 ng/mL ) BACKGROUND A large variety of therapeutic agents are being used for the treatment of vitiligo , but treatment remains a challenge . Recently , monochromatic phototherapies such as 311-nm narrowb and ultraviolet B therapy and 308-nm xenon chloride excimer laser have been reported to be an effective and safe therapeutic option in children and adult patients with vitiligo . Single reports stipulate that the addition of topically applied calcipotriol to phototherapy increases its effectiveness . OBJECTIVE The purpose of the present pilot study was to determine if the addition of topical calcipotriol increases the efficacy of the 308-nm xenon chloride excimer in the treatment of vitiligo . METHODS Ten patients with vitiligo with essentially bilateral symmetrical lesions were enrolled in this prospect i ve right/left comparative , single-blinded trial conducted over a 15-month period . All patients received 308-nm XeCl excimer laser therapy three times weekly . Calcipotriol ointment ( Daivonex ) was applied to lesions on one side of the body twice daily . RESULTS After 24 treatments ( 8 weeks ) , nine patients were evaluated . Eight patients showed evidence of repigmentation on both body sides , with no significant difference between the body side treated with calcipotriol and excimer laser and the side treated with excimer laser alone . The mean repigmentation rate was 22.4 % ( 1 - 37 % ) . CONCLUSION The addition of calcipotriol ointment to 308-nm xenon chloride excimer laser phototherapy does not significantly enhance its efficacy . Small additive effects must be investigated in a larger trial OBJECTIVE Evaluation of the efficiency of topical calcipotriol monotherapy in vitiligo . MATERIAL S AND METHODS This was a prospect i ve , right/left comparative , open study at the Dermatology Department at the University Hospital in Nice , France . Twenty-four patients with localized or generalized vitiligo with symmetrical lesions were included . The main outcome measure was the evaluation of the percentage of repigmentation in treated target lesions and untreated control lesions for each patient . RESULTS AND CONCLUSIONS Topical calcipotriol in monotherapy is not an effective treatment of vitiligo Background : Low vitamin D levels have been associated with several autoimmune diseases . Vitiligo could be associated with low vitamin D levels . Objective : To determine the level of serum vitamin D in vitiligo patients compared to controls and reveal the possible association of vitamin levels with the pathogenesis of vitiligo . Patients and Methods : A case-controlled study was conducted . After excluding factors that may affect serum vitamin D levels , blood sample s were taken from vitiligo patients and controls . The association between vitamin D levels and various vitiligo subgroups ( duration of vitiligo , site of onset , age , etc ) was measured and correlated . Results : A total of 150 vitiligo patients , 90 ( 60 % ) males with a mean age of 30.6 ± 11.4 years , were recruited . The study also had 150 age- and gender-matched vitiligo-free control subjects . There was no significant difference in median serum vitamin D levels between the cases and the controls ( P = .25 ) . The serum levels of vitamin D of the vitiligo patients were found to be lower in males ( P = .01 ) , the younger age group ( P = .01 ) , and patients not treated with ultraviolet ( UV ) treatment ( P = .01 ) . Conclusion : There is no difference between the vitamin D levels of the vitiligo patients and the control subjects . However , deficiency of 25(OH)D levels within the vitiligo subgroups may be linked to younger age , male gender , short duration of vitiligo , and non-use of phototherapy BACKGROUND Vitiligo is an autoimmune depigmentation disorder , commonly associated with systemic autoimmune diseases . Deficient serum 25-hydroxyvitamin D ( 25(OH)D ) levels have been noted in some patients with autoimmune diseases . AIM To evaluate serum 25(OH)D levels in vitiligo patients with and without systemic autoimmune diseases . METHODS A case-control study was conducted on 40 vitiligo patients ( 20 patients with systemic autoimmune diseases and 20 patients without autoimmune diseases ) and 40 age- , gender- and skin phototype-matched healthy controls . Serum 25(OH)D was measured in all subjects , divided into : normal or sufficient ( ≥ 30 ng/ml ) , insufficient ( < 30- > 20 ng/ml ) and deficient ( ≤ 20 ng/ml ) levels . RESULTS One patient with vitiligo ( 2.5 % ) versus 33 healthy controls ( 82.5 % ) have sufficient serum 25(OH)D levels while 39 patients ( 97.5 % ) versus 5 controls ( 12.5 % ) have deficient 25(OH)D levels with significantly lower serum 25(OH)D levels in patients compared to controls ( P-value < 0.001 ) . The other 2 healthy controls have insufficient 25(OH)D levels . Patients with vitiligo and autoimmune diseases have lower serum 25(OH)D levels than vitiligo patients without autoimmune diseases but with no significant difference . No significant correlations existed between age of the patients , duration of vitiligo , duration of associated autoimmune diseases , affected body surface area and serum 25(OH)D levels of patients . CONCLUSION Deficient serum 25(OH)D levels are present in vitiligo patients with and without systemic autoimmune diseases . Accordingly , screening for vitamin D deficiency seems of value in vitiligo patients for the possibility of vitamin D supplementation Background Recent advances in the pathophysiology of vitiligo have demonstrated defective calcium homeostasis in depigmented skin . 1,25‐Dihydroxyvitamin D3 may be involved in the regulation of melanin synthesis , and receptors for 1,25‐dihydroxyvitamin D3 have been demonstrated on melanocytes 
    Output:
    
This meta- analysis identifies a significant relationship between low 25-hydroxyvitamin D levels and vitiligo , but does not prove causation .