In this podcast, we’ll discuss a study highlighted at the 2015 Gastrointestinal Cancers Symposium that examines the relationship between Vitamin D levels and survival in patients with advanced colorectal cancer.
ASCO: You're listening to a podcast from Cancer.Net. This cancer information website is produced by the American Society of Clinical Oncology, known as ASCO, the world's leading professional organization for doctors that care for people with cancer.
In today's podcast, we'll discuss a study highlighted at the 2015 Gastrointestinal Cancer Symposium, that examines the relationship between Vitamin D levels and survival in patients with advanced colorectal cancer. This podcast will be led by Dr. Smitha Krishnamurthi, who is a medical oncologist at the University Hospitals Case Medical Center and associate professor of medicine at the Case Western Reserve University. Dr. Krishnamurthi is also a member of ASCO's Cancer Communications Committee, as well as a member of the news planning team for the 2015 Gastrointestinal Cancer Symposium. ASCO would like to thank Dr. Krishnamurthi for summarizing this study.
Dr. Krishnamurthi: Hello. I'm Smitha Krishnamurthi, a medical oncologist at the Siedman Cancer Center in Cleveland, Ohio. I'll be discussing a study of Vitamin D in patients with advanced colorectal cancer. Vitamin D helps us absorb calcium from food we eat. We also know that Vitamin D prevents bone loss and can prevent bone fractures. There have been earlier studies suggesting that Vitamin D could have anti-cancer effects, such as reducing the risk of developing polyps and colorectal cancer. The study I'm discussing today was a large study of over 1,000 patients with advanced colorectal cancer. These patients were enrolled on a national clinical trial comparing the effect of two different biologic treatments combined with chemotherapy. The Vitamin D level in the blood was measured in all the patients at the start of the study. The patients also filled out questionnaires about their diet and lifestyle behavior, such as smoking and exercise. Keep in mind, the normal Vitamin D level is over 30 nanograms per milliliter and a level of 30 to 50 is considered ideal. Insufficient levels are in the range of 20 to 30, and Vitamin D deficiency is a level less than 20.
In this study, it was found that half the patients had a Vitamin D level below 17, which is deficient and it's quite low. Most of our Vitamin D is made in our skin when exposed to sunlight. People with pigmented skin tend to make less Vitamin D in the skin and are more likely to have low Vitamin D levels. We also get Vitamin D through our diet, through foods such as fatty fish and eggs and fortified cow's milk. And another source is from taking Vitamin D capsules from the pharmacy.
Not surprisingly, this study found that African American patients and those with lower levels of Vitamin D in their diet, as well as those who took less Vitamin D through supplements, and those who had their blood drawn in winter or fall, had lower blood Vitamin D levels. Patients who are older and less active and had a higher body mass also had lower Vitamin D levels. Interestingly, the study found that patients who had a Vitamin D level in the top 20% live longer compared to patients with the lowest Vitamin D levels. On average, patients lived eight months longer if they had a Vitamin D level in the highest 20%. This difference in survival time was found after adjusting for other factors that could affect the prognosis. What was also really interesting was that in patients with higher blood Vitamin D levels, it took on average two months longer for their cancer to become resistant to chemotherapy. This suggests that when the Vitamin D level is high the cancer may be a slower growing type or that the chemotherapy may work better. These findings are promising and give us hope that maybe we can improve outcomes for our patients with colorectal cancer with the Vitamin D. However, we can't be sure from these findings that Vitamin D was the reason why patients lived longer. We need randomized control trial in which patients with colorectal cancer are randomly assigned to take Vitamin D versus a placebo. That's the only kind of study that can prove a benefit, if there is one, for Vitamin D.
We do know that Vitamin D is important for bone health and we also know that many patients, especially those living in northern regions or with pigmented skin, are at risk for low Vitamin D levels. So I encourage patients to talk to their primary care doctors about having Vitamin D levels checked. And if the Vitamin D level is insufficient or deficient, patients should be treated with Vitamin D for their bone health. And it may help to prevent colorectal cancer or slow down the growth of the cancer.
ASCO: Thank you, Dr. Krishnamurthi. More information from 2015 Gastrointestinal Cancer Symposium can be found at www.cancer.net.
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