Page 102 - Vitamin D and Cancer

4 The Epidemiology of Vitamin D and Cancer Risk 89

for B cell lymphomas, but not for T cell lymphomas. However, the numbers for the
T cell lymphomas were small and thus the results were inconclusive.
A case–control study based on death certificates of residential and occupational
sun exposure and NHL mortality was conducted, as described above (Sect. 4.3.4)
[82]. The study, conducted in 24 states in the USA, and based on over 33,000 fatal
cases of NHL, found a 17% reduction in risk of NHL mortality that the RR for
those residing in states with the highest sunlight exposure (multivariate RR = 0.83
(95%CI = 0.81 to 0.86). Intriguingly, the risk reduction was remarkably high for
those under 45 years of age (RR = 0.44 (95%CI = 0.28–0.67). The risk of NHL
mortality was also reduced with higher occupational sunlight exposure (RR = 0.88;
95% CI = 0.81–0.96). Besides its effects on vitamin D levels, chronic UV exposure
has effects on the immune system [83], and hence sun light exposure could poten-
tially influence neoplasms of the immune system through mechanisms besides
vitamin D.

4.10 Total Cancer

4.10.1 Circulating 25(OH)D

Three relatively small studies examined circulating 25(OH)D in relation to risk of
total cancer. One analysis was conducted in the Third National Health and Nutrition
Examination Survey [25]. In this analysis, there were 16,818 participants who were
followed from 1988 to 1994 through 2000. Over this follow-up, 536 cancer deaths
were identified. Baseline vitamin D status was not significantly associated with
total cancer mortality, although a nonsignificant inverse trend (P = 0.12) was
observed in women only. There were generally too few specific cancer sites to be
examined, but colorectal cancer mortality was inversely related to serum 25(OH)D
level (discussed above), and a nonsignificant inverse association was observed for
breast cancer.
Two small studies were conducted in specialized populations. In the Ludwigshafen
Risk and Cardiovascular Health study, 25(OH)D was measured in 3,299 patients
who provided a blood sample in the morning before coronary angiography [84].
These subjects were followed for a median period of about 8 years, over which 95
cancer deaths were recorded. The multivariate analysis adjusted for age, sex, body
mass index, smoking, retinol, exercise, alcohol, and diabetes history. Higher
25(OH)D level at baseline appeared to be associated with a lower risk of total can-
cer (multivariate RR = 0.45; 95%CI = 0.22–0.93) for the fourth quartile versus the
first quartile of 25(OH)D. The risk decrease was monotonic, and the RR per
increase of 25 nmol/L in serum 25(OH)D concentrations was 0.66
(95%CI = 0.49–0.89).
The other study examined pre-transplant 25(OH)D levels in 363 renal transplant
recipients at Saint-Jacques University Hospital at Besancon, France [85]. Mean