MONDAY, April 18, 2005 (HealthDay News) -- Does having lung cancer surgery during a sunny time of year improve your chances of survival?
Maybe, according to Harvard researchers.
The reason is vitamin D. The human body naturally produces vitamin D after sun exposure, and researchers found that people who had surgery for early-stage lung cancer fared better if they had their surgery during a sunnier time of the year or if they had a high intake of vitamin D before surgery.
In fact, those who had surgery in very sunny months and had a high intake of vitamin D were more than twice as likely to surpass the five-year survival mark as people who had winter surgeries and a low intake of vitamin D, the study found.
"The take-home message from this study is that if these findings hold up, a relatively simple intervention could have a relatively large impact," said principal investigator Dr. David Christiani, a professor of epidemiology at the Harvard School of Public Health. "This study showed a pretty strong relationship between vitamin D intake or season and disease-free and overall survival."
However, both the researchers and other lung cancer experts stressed the findings are no reason to postpone needed cancer surgery to a brighter time of year.
The findings were presented April 18 at the annual meeting of the American Association for Cancer Research in Anaheim, Calif.
More than 170,000 Americans will be diagnosed with lung cancer this year, according to the American Cancer Society. Sixty percent of those diagnosed will die within a year, and for 75 percent of those with lung cancer, the disease will prove fatal within two years of diagnosis. Lung cancer is the deadliest of all cancers for both men and women, and more than 160,000 people die from the disease each year.
Symptoms include a cough that won't go away and worsens over time, constant chest pain, coughing up blood, hoarseness, wheezing and shortness of breath, according to the National Cancer Institute. The most common cause of lung cancer is smoking. Other causes include exposure to secondhand smoke, radon, asbestos or certain air pollutants.
For this study, Christiani and his colleagues looked at outcomes in 456 people with early stage non-small cell lung cancer. Eighty percent had stage I cancer, and the remaining 20 percent had more advanced stage II cancer. All had surgery to remove the cancer, while 9 percent also received radiation and 1 percent received chemotherapy.
The average age of people in the study was 69. Most were white, 47 percent were female and 40 percent were current smokers. The average follow-up time was just under six years.
After five years, 234 of the study participants had died. Older age, current smoking and more advanced cancer were risk factors for dying, and the researchers adjusted for these factors in their analysis.
Five-year survival rates were 25 percent higher for those who had surgery in the spring, summer or fall compared to those who had surgery in the winter, the researchers found. Overall survival rates were 50 percent for winter surgeries, 57 percent for spring/fall surgeries and 59 percent for summer surgeries.
The researchers also had dietary information for 323 of the study participants. Those with the highest intake of vitamin D were 28 percent less likely to die.
When surgical season was combined with vitamin D intake, the researchers found a 72 percent five-year survival for those who had surgery in the summer and had the highest vitamin D intake, compared to 30 percent for those who had winter surgery and low vitamin D intake.
Christiani said this study didn't look at the mechanism by which vitamin D might increase survival odds, but said that other studies have shown that vitamin D may have "anti-proliferative and anti-invasive properties." That means vitamin D may modify the way lung cancer tumor cells behave and make them less likely to grow fast and less likely to invade other parts of the body.
"This is an interesting observation, but it won't influence the way I would practice today," said Dr. Jay Brooks, chairman of hematology and oncology at Ochsner Clinic Foundation Hospital in New Orleans.
Brooks pointed out that past studies have shown significant benefits for other vitamins that with additional research didn't pan out.
Additionally, because the earlier you get treatment for lung cancer, the better your chances for survival are, Brooks cautioned, "People shouldn't wait to get surgery."
The researchers agreed. "This study in no way suggests that people should try to time their cancer surgeries for a particular season. But, if validated, it may mean that increasing a patient's use of vitamin D before such surgery could offer a survival benefit," one of Christiani's Harvard colleagues, Dr. Wei Zhou, said in a statement.
The American Cancer Society offers more information on lung cancer treatment.