People who undergo surgery for lung cancer tend to have better odds of survival if they have higher levels of vitamin D in their bloodstream, says a new study from Harvard Medical School and Brigham and Women's Hospital in Boston.1
The researchers took into account various sources of vitamin D consumption, including foods, supplements, and the sun.
The findings were unveiled at a meeting of the American Association for Cancer Research in California this past April.
"This study in no way suggests that people should try to time their cancer surgeries for a particular season. That would obviously be impossible," said Wei Zhou, PhD, a research scientist at the Harvard School of Public Health who took part in the study. "But if validated, it may mean that increasing a patient's use of vitamin D before such surgery could offer a survival benefit."
Lung Cancer and IPF: Distinct But Sometimes Concurrent
Lung cancer is a disease that can occur simultaneously with a scarring condition of the lung known as idiopathic pulmonary fibrosis (IPF), though they are two distinct pathologies.2 The frequency of these two diseases occurring at the same time ranges from about 5% in the United States to nearly 50% of cases in Japan.
There are two types of lung cancer: non-small cell and small cell lung cancer. The former is more common and grows more slowly. It is also less likely to spread to other parts of the body than small cell lung cancer. Those who smoke cigarettes, cigars, and pipes are at risk for the disease. But exposure to environmental tobacco smoke, such as that in the air when someone else smokes, as well as to radon gas are also risk factors.
Lung cancer symptoms include a persistent cough, constant chest pain, coughing up blood, shortness of breath, pneumonia or bronchitis, swelling of the neck and face, loss of appetite or weight loss, and fatigue.3
The lung scarring associated with IPF greatly reduces the ability of the lungs to absorb oxygen and eliminate carbon dioxide, a waste gas produced by the various cells of the body. IPF is found in about 200 lung disorders known collectively as interstitial lung diseases (ILD). The prognosis for patients is generally poor, although those who are younger, female, have milder shortness of breath, and respond better to therapy have better odds of survival. The cause of IPF isn't known.4
In people with IPF, a frequent complication is pulmonary hypertension, in which the blood pressure in the pulmonary artery leading from the heart to the lungs rises to abnormally high levels.4
Does Vitamin D Boost Survival?
To evaluate the possible impact of vitamin D on lung cancer survival, the Boston researchers measured the odds of survival in 456 patients with early stage non-small cell lung cancer. A variety of tumor types was noted in the patients, of whom nearly half were smokers. A small number of the patients underwent radiation treatment or chemotherapy following surgery.
The study team looked at two separate outcomes in the study: outcome based on vitamin D consumption from food and supplements, derived from questionnaires given to 321 patients, and outcomes based on the season in which surgery was performed (In summer, more amounts of sunlight increase vitamin D intake compared to the winter months).
When the study authors looked at each patient's odds of survival free of lung cancer, they found that those who had surgery in the winter were 40% more likely to die from the cancer, on average, compared to those who had the operation during the summer months. Five-year survival odds were 54% for those who had surgery in the winter, 56% for those who underwent surgery in the spring or fall, but 70% for patients who had surgery in the summer.
When they examined the odds of overall survival in the patients, those who had surgery in the winter were about 25% more likely to die than those who were operated on in the summer. Five-year overall survival rates ranged from 50% for those who had surgery in the winter months to 59% for those who had summer surgery, the investigators noted.
Combined Effect Even Better
They then looked at the patients' chances of survival when vitamin D consumption from food or supplements was combined with surgery in the summer months. They found summer surgery patients had a three-fold better chance of disease-free survival and more than four times better odds of overall survival compared to those who underwent surgery in the winter. (The 5-year disease-free survival odds were 83% versus 46% for summer and winter surgeries, respectively. Overall survival chances were 72% versus only 30%, respectively).
"Animal studies have shown that treatment of cancer with vitamin D demonstrates both anti-proliferative and anti-invasive properties," Zhou explained. "But we don't know if that is true in humans with cancer. So, the best way we can make some sort of association is to look at differences in what happens after treatment of cancer between patients who use high levels of vitamin D through their diet and supplements, as well as through sunlight exposure, compared to patients who do not."
More Questions to Pursue
The underlying mechanism behind the apparent association between vitamin D and lung cancer survival isn't known yet, Zhou added.
"This is the first study suggesting that vitamin D levels at the time of treatment may be an important predictor for lung cancer survival," the researchers wrote. "The results should be confirmed by measuring serum vitamin D levels during treatment in a larger prospective study, as well as among advanced non-small cell lung cancer patients," they added.
1. Vitamin D predicts overall survival in early state non-small cell lung cancer patients. American Association for Cancer Research 96th Annual Meeting. 2005 Apr 16-20. Anaheim, CA.
2. Yoshimura A, Kudoh S. Idiopathic pulmonary fibrosis and lung cancer [Translated from Japanese]. Gan To Kagaku Ryoho 2003 Feb;30(2):215-22.
3. National Cancer Institute. National Institutes of Health (NIH). What You Need to Know About Lung Cancer. Available at: http://www.cancer.gov/cancertopics/wyntk/lung/page1. Accessed July 21, 2005.
4. Coalition for Pulmonary Fibrosis. Idiopathic Pulmonary Fibrosis: Information for Patients and Caregivers. Available at: http://www.coalitionforpf.org/Patients/. Accessed July 21, 2005.
John Martin is a long-time health journalist and an editor for Priority Healthcare. His credits include overseeing health news coverage for the website of Fox Television's The Health Network, and articles for the New York Post and other consumer and trade publications.
