Indeed. This paper reported significantly increased survival rates for those with higher 25-hydroxyvitamin D concentrations at time of cancer diagnosis for several types of cancer: Tretli S, Schwartz GG, Torjesen PA, Robsahm TE. Serum levels of 25-hydroxyvitamin D and survival in Norwegian patients with cancer of breast, colon, lung, and lymphoma: a population-based study. Cancer Causes Control. 2012;23(2):363-70.

We have suggested that African-Americans have poorer cancer survival rates than white Americans due to lower 25OHD concentrations:  Grant WB, Peiris AN. Differences in vitamin D status may account for unexplained disparities in cancer survival rates between African and White Americans. Dermatoendocrinol. 2012;4(2): 85-94.

It may be that physicians are afraid to prescribe vitamin D to cancer patients since doing so has not been approved in general due to lack of clinical trials.

Dr. Rulewski,

I am not a clinician, and I am not making a vitamin D intake recommendation for patients either. Your question, however, is of immense interest. Moreover, vitamin D intake recommendation concerns a range of biomedical scientists such as clinical scientists, nutritional biochemists, biochemists/molecular medicine scientists, nutritional epidemiologists, and so on.

With mounting publicity highlighting the potential salutary benefits of supplemental vitamin D, a pivotal role has been ascribed for vitamin D in chronic disease prevention. A sufficient beneficial role for vitamin D has become evident only for bone and skeletal health. Some epidemiological and preclinical studies have lent support to the potential application vitamin D as preventative and therapeutic anticancer agents, with notable associations especially observed with low vitamin D status and overall cancer outcome.  Observational studies have indicated associations between low sun exposure, poor vitamin D status, and elevated risk of developing colorectal and breast cancer. In general, randomized clinical trials examining the association of vitamin D exposure and cancer prevention have yielded inconclusive and inconsistent results. Of salience are the following questions:  vitamin D inadequacy and cancer risk; higher intake of vitamin D and cancer prevention; the prospect of increased risk of developing cancer in individuals owing to greater intake of vitamin D; the long-term health effects resulting from high doses of vitamin D and from extended duration of supplementation, and the association of health effects with different baseline vitamin D levels.

The Institute of Medicine (IOM) has concluded that accumulating scientific evidence supports a marked role of calcium and vitamin D in skeletal health, consistent with a cause-and-effect relationship.  For extraskeletal outcomes, the (IOM) Committee opined that the evidence accrued was inconsistent and inconclusive as to causality, and insufficient to impart nutritional requirements.

Commentary

Vitamin D and Cancer: Diversity, Complexity, and Still a Ways to Go

Demetrius Albanes

Cancer Prev Res August 2015 8:657-661; Published OnlineFirst August 3, 2015;doi:10.1158/1940-6207.CAPR-15-0207

http://cancerpreventionresearch.aacrjournals.org/content/8/8/657

In order to understand vitamin D intake and associated implications for carcinogenesis, this commentary suggests diverse lines of investigations such as the elucidation of organ site–specific biologic mechanisms, prospective serologic analyses, testing of vitamin D–related genetic variation, and short-term clinical–metabolic biomarker studies of multidose vitamin D supplementation, including metabolomic profiling of controlled supplementation in clinical  trials.

Circulating Vitamin D Levels and Risk of Colorectal Cancer in Women.

Cancer Prev Res August 2015 8:675-682; Published OnlineFirst March 26, 2015; doi:10.1158/1940-6207.CAPR-14-0470

http://cancerpreventionresearch.aacrjournals.org/content/8/8/675

“These results support a possible association between plasma 25(OH)D and risk of colorectal cancer in women.”   

Regards...

Two clinical trials have found a beneficial effect of vitamin D and calcium supplementation on risk of cancer:

Lappe JM, Travers-Gustafson D, Davies KM, Recker RR, Heaney RP. Vitamin D and calcium supplementation reduces cancer risk: results of a randomized trial. Am J Clin Nutr. 2007 Jun;85(6):1586-91.

Bolland MJ, Grey A, Gamble GD, Reid IR. Calcium and vitamin D supplements and health outcomes: a reanalysis of the Women's Health Initiative (WHI) limited-access data set. Am J Clin Nutr. 2011 Oct;94(4):1144-9.

The reasons for only two such trials include poor trial design and lack of interest due to little profit to be made from a naturally occurring compound that is very inexpensive:

Heaney RP. Guidelines for optimizing design and analysis of clinical studies of nutrient effects. Nutr Rev. 2014 Jan;72(1):48-54.

As the evidence that vitamin D is more effective in reducing cancer mortality rates than cancer incidence rates, there should be more effort made to use vitamin D for those diagnosed with cancer.

Grant WB, Garland CF. Vitamin D has a greater impact on cancer mortality rates than cancer incidence rates, BMJ 2014 Apr 29;348:g2862.

In addition, ecological studies strongly support the role of UVB and vitamin D in reducing risk of many types of cancer:

Moukayed M, Grant WB. Molecular link between vitamin D and cancer prevention. Nutrients. 2013;5(10):3993-4023.

There have been more than 10,000 publications on vitamin D since the IOM report was issued, so it cannot be used as an authority any more.

Circulating 25-hydroxyvitamin D and survival in women with ovarian cancer. Am J Clin Nutr 2015 102: 1 109-114

http://ajcn.nutrition.org/content/102/1/109.short?rss=1

In their cohort, higher serum 25(OH)D concentrations at diagnosis were associated with longer survival among women with ovarian cancer.

Circulating Vitamin D Levels and Risk of Colorectal Cancer in Women.

Cancer Prev Res August 2015 8:675-682; Published OnlineFirst March 26, 2015; doi:10.1158/1940-6207.CAPR-14-0470 http://cancerpreventionresearch.aacrjournals.org/content/8/8/675

“These results support a possible association between plasma 25(OH)D and risk of colorectal cancer in women.”  

http://www.mayoclinicproceedings.org/article/S0025-6196%2815%2900185-8/abstract

DOI: http://dx.doi.org/10.1016/j.mayocp.2015.02.012

Changing Incidence of Serum 25-Hydroxyvitamin D Values Above 50 ng/mL: A 10-Year Population-Based Study. Dudenkov, D.V., Yawn, B.P., Oberhelman, S.S. et al. Mayo Clin Proc. 2015; 90: 577–586

“The incidence of 25(OH)D values above 50 ng/mL increased significantly between 2002 and 2011 without a corresponding increase in acute clinical toxicity.” (IOM cautioned that blood levels of 25(OH)D should not be more than 50 ng/mL.)

Vitamin D Is Not as Toxic as Was Once Thought: A Historical and an Up-to-Date Perspective

http://www.mayoclinicproceedings.org/article/S0025-6196%2815%2900244-X/fulltext

DOI: http://dx.doi.org/10.1016/j.mayocp.2015.03.015

“The evidence is clear that vitamin D toxicity is one of the rarest medical conditions and is typically due to intentional or inadvertent intake of extremely high doses of vitamin D (usually in the range of >50,000-100,000 IU/d for months to years).  Simply reducing the calcium intake, wearing sun protection to prevent vitamin D production, and eliminating all vitamin D from dietary sources will result in a gradual decrease in serum 25(OH)D levels, with no significant sequelae from the toxicity.” 

A new analysis of data has confirmed the need for higher RDA of vitamin D, which pointed out that the Food and Nutrition Board (FNB) made a statistical error when they arrived  at the recommended dietary allowance (RDA) for vitamin D in 2010. Dr. Robert Heaney and colleagues, in a letter to the statisticians,  confirmed that higher vitamin D supplementation is required to reach healthy vitamin D levels in 97.5% of the population by using data from the GrassrootsHealth Study (GRH). They concluded, “Since an RDA, by definition, relates to intake from all sources, it is clear that total intake required to achieve 20 ng/mL in 97.5% of the cohort must be close to 7000 IU per day, not substantially different from that calculated by Veugelers and Ekwaru.”

Heaney R., et al. Letter to Veugelers, P.J. and Ekwaru, J.P., A Statistical Error in the Estimation of the Recommended Dietary Allowance for Vitamin D. Nutrients 2014. Nutrients, 2015.

Nutrients 2015, 7(3), 1688-1690; doi:10.3390/nu7031688

http://www.mdpi.com/2072-6643/7/3/1688/htm 

While i am aware that there are many studies showing an association between vitamin D deficiency and cancer and poor outcomes in cancer patients, the medical community only appear to react to randomized prospective controlled studies. As far as i know the Lappe study is the only one that is prospective and randomized, and as always, being a fairly small study the reaction is that this needs to be confirmed in larger trials.  Are there any other randomized prospective studies out there that I am not aware of?

Chithan, 

you said "In general, randomized clinical trials examining the association of vitamin D exposure and cancer prevention have yielded inconclusive and inconsistent results" 

The only prospective study (other than Lappe) that I know of is the following:

Natl Cancer Inst. 2008 Nov 19;100(22):1581-91. doi: 10.1093/jnci/djn360. Epub 2008 Nov 11.

Calcium plus vitamin D supplementation and the risk of breast cancer.

Chlebowski RT, Johnson KC, Kooperberg C, Pettinger M, Wactawski-Wende J, Rohan T, Rossouw J, Lane D, O'Sullivan MJ, Yasmeen S, Hiatt RA, Shikany JM, Vitolins M, Khandekar J, Hubbell FA; Women's Health Initiative Investigators.

But the dose of vitamin D used in the above study was only 400IU which we now know is not much more than a placebo. So i would say that the appropriate studies have simply not been done, not as you suggest that the results have been inconclusive and inconsistent.

Nigel,

I concur with you. Prospective studies examining association of vitamin D supplementation with the risk of cancer are meager. Thank you!

Do not forget this reanalysis of the WHI study. It shows that women with low 25(OH)D at time of enrollment had reduced risk of cancer in that study:

Am J Clin Nutr. 2011 Oct;94(4):1144-9. doi: 10.3945/ajcn.111.015032. Epub 2011 Aug 31.

Calcium and vitamin D supplements and health outcomes: a reanalysis of the Women's Health Initiative (WHI) limited-access data set.

Bolland MJ1, Grey A, Gamble GD, Reid IR.

Abstract

BACKGROUND:

Frequent use of personal, nonprotocol calcium supplements obscured an adverse effect of coadministered calcium and vitamin D (CaD) on cardiovascular risk in the Women's Health Initiative (WHI).

OBJECTIVE:

We investigated the effects of the use of personal calcium or vitamin D supplements on other outcomes in the WHI CaD Study (WHI CaD) by using the WHI limited-access clinical trials data set.

DESIGN:

The WHI CaD was a 7-y, randomized, placebo-controlled trial of CaD (1 g Ca/400 IU vitamin D daily) in 36,282 community-dwelling, postmenopausal women. The incidence of total cancer (excluding nonmelanoma skin cancers), breast and colorectal cancers, hip and total fracture, and mortality was assessed by using Cox proportional hazards models.

RESULTS:

In the WHI CaD, interactions between the use of either personal calcium or vitamin D supplements and CaD were found for total, breast, and colorectal cancers but not for fracture or mortality. In 15,646 women (43%) who were not taking personal calcium or vitamin D supplements at randomization, CaD significantly decreased the risk of total, breast, and invasive breast cancers by 14-20% and nonsignificantly reduced the risk of colorectal cancer by 17%. In women taking personal calcium or vitamin D supplements, CaD did not alter cancer risk (HR: 1.06-1.26).

CONCLUSIONS:

For women in the WHI CaD who were not taking personal calcium or vitamin D supplements at randomization, CaD decreased the risk of total, breast, and colorectal cancers and did not change the risk of fractures or total mortality. The nonskeletal effects of CaD may be more important than the skeletal effects and should be considered when evaluating these supplements. The WHI CaD trial is registered at clinicaltrials.gov as NCT00000611.

besides the direct involvement in cancers several animal studies have been done regarding proof of vitd role in deficiency being involved as a causative agent for fibroids in women where besides the aetiological factors being sSPRM used to prevent the further growth vitd hS BEEN FOUND to be of very big use in seeing to it that after stoppage of the agent recurrence doesnt occur as long term prevention was not possible and large studies have been carried in nimal models by hysder et al group  specially in afroamerican women who tend to develo tumours in very young age and besides genetic factors aetiolgy is very illunderstood and vit d dihydroxy has been found to be corelate with the melanin absorption deficiency they develop becausof their skins having a particular reesistance to the absorption and nutritional deficiencies they tend to develop and supplementation with vitd prevents development of tumours in these women and i suppose since in humans large rcts ae not possible regarding simple cancer treatments long bterm treatments from this can be further taken as a point to try as it has seemed to workin the noncancerous fibroid model

so if we could design the optimal study to show the effect on survival what would folk suggest.  I think I would  go with a high vis low dose in advanced lung or breast cancer, with a sequential analysis so that as soon as the survival benefit reaches statistical significance the study could be stopped. Such a design would limit the number of patients who are lost but would not demonstrate fully how much the survival is actually improved by as the study would  be stopped at statistical significance. Then of course the question is how big does the study need to be to be convincing enough that we  don't end up with the conclusion that the findings need to be confirmed in larger studies?