Vitamin D helps improve survival from bowel and skin cancer

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In the first study [1] researchers from the Dana-Farber Cancer Institute, Boston followed 1017 bowel cancer patients for around nine years.

Using information about UV-B and sunlight exposure, skin type, body-mass index, and vitamin D intake from food and supplements they estimated the amount of vitamin D in patients' blood at the time of diagnosis.

The results showed that those with higher vitamin D scores after being diagnosed with cancer were 50 per cent less likely to die from the disease – compared to those with lower vitamin D scores.

Professor Kimmie Ng, study author, said: "Our study shows that levels of vitamin D after colorectal cancer diagnosis may be important for survival. We are now planning further research in patients with bowel cancer to see if vitamin D has the same effect, and to investigate how vitamin D works with molecular and genetic pathways in the cell to fight cancer."

The second study [2] – funded by Cancer Research UK and the National Institutes of Health – found that malignant melanoma patients with the lowest levels of vitamin D in their blood at the time they were diagnosed were 30 per cent more likely to relapse from the disease than those with the highest levels.

The researchers from Leeds also found that patients who have higher levels of vitamin D at diagnosis have thinner tumours at diagnosis.

Professor Julia Newton Bishop, study author at the Leeds Institute of Molecular Medicine, said: "It's common for the general public to have low levels of vitamin D in many countries. Melanoma patients tend to avoid the sun as sunburn is known to increase the risk of melanoma. We use sunshine to make vitamin D in the skin, so melanoma patients' levels of vitamin D may be especially low.

"Our results suggest that melanoma patients may need to get vitamin D by eating fatty fish or by taking supplements to ensure they have normal levels. But we are continuing to carry out research to find out the optimum level of vitamin D. There's some evidence from other health studies that high levels of vitamin D are also harmful – so we should aim for a normal level rather than a very high one."

Sara Hiom, director of health information at Cancer Research UK, said: "Both these studies support the theory that higher levels of vitamin D can improve the chance of surviving cancer. The key is to get the right balance between the amount of time spent in the sun and the levels of vitamin D needed for good health.

"But protection from burning in the sun is still vital. Cancer Research UK's SunSmart campaign advises that people with lots of moles, red hair fair skin and a family history of the disease should take extra care in the sun as they are more at risk of the most dangerous form of skin cancer Anyone who is worried about changes in their moles should go to their GP."

Reference

1. Ng K, Wolpin BM, et al. Prospective study of predictors of vitamin D status and survival in patients with colorectal cancer. British Journal of Cancer 2009. doi: 10.1038/sj.bjc.6605262
2. Newton-Bishop JA, Beswick S2, et al. Serum 25-hydroxyvitamin D3 levels are associated with Breslow thickness at presentation and survival from melanoma. Journal of Clinical Oncology 2009. doi: 10.1200/JCO.2009.22.1135

klíčová slova: bowel cancer, skin cancer, survival, vitamin D