Recent in vitro, animal, and human research has suggested a possible role for vitamin D in decreasing cancer incidence, mortality, or both. A new study that used data collected prospectively during the third National Health and Nutrition Examination Survey (NHANES) showed no association between levels of vitamin D in the blood and total cancer mortality, but did find a significant association between higher levels of circulating vitamin D and reduced risk of colorectal cancer mortality.
"Most of the previous studies on cancer mortality [and vitamin D] have been ecologic studies or have been based on surrogates for vitamin D levels. This is the first to look at actual measured levels and total cancer mortality," says Dr. Michal Freedman from NCI's Division of Cancer Epidemiology and Genetics, lead author of the study, which was published online October 30 in the Journal of the National Cancer Institute.
Between 1988 and 1994, the investigators from NCI and the Centers for Disease Control and Prevention collected data from 16,818 NHANES participants aged 17 or older, including demographic and lifestyle factors that may contribute to increased cancer risk. Each participant contributed a blood sample that was measured for vitamin D levels.
"We found no association between [vitamin D] and total cancer mortality in the…NHANES III study population," state the authors. However, participants with serum vitamin D levels at or above 80 nmol/L had a significantly lower risk of colorectal cancer mortality than participants with levels lower than 50 nmol/L.
The investigators cite several strengths of their study, including use of a study population that was derived from a representative sample of the U.S. population, and inclusion of many variables known to influence cancer risk. They also acknowledge limitations such as a low number of total cancer deaths to analyze and a single point of measurement for vitamin D, which may not represent blood levels over time.
"The relationship between nutritional factors and colorectal as well as other cancers is complicated…Randomized clinical trials of the effects of vitamin D on the incidence of colonic polyps and invasive cancer are needed," state Drs. Cindy Davis of NCI's Division of Cancer Prevention and Johanna Dwyer of the NIH Office of Dietary Supplements in an accompanying editorial.
Brain Cancer Trial Finds Longer Survival with Temozolomide Regimen
Two years ago, researchers reported that the drug temozolomide could improve the survival of patients with glioblastoma brain cancer when given along with and following radiation therapy. The survival benefit was about 2.5 months, which was significant for the disease. Now, additional follow-up shows that some patients have survived for several years beyond the 6 to 12 months that is typical for this deadly disease.
The results, from a phase III clinical trial involving more than 500 European and Canadian patients, were presented last week at the annual meeting of the American Society for Therapeutic Radiology and Oncology (ASTRO) in Los Angeles.
The updated results show that 12.9 percent of patients who received temozolomide during and after radiation treatment lived for 4 years compared with 3.8 percent of those who received radiation alone and also lived for 4 years. Patients who survived for 4 years after diagnosis were mostly younger than 50 and in otherwise good health without any prior major medical condition. Approximately 28 percent of these patients who were treated with temozolomide and radiation lived for 4 years, versus only 7 percent of patients who received only radiation therapy.
"The survival advantage conferred by the addition of temozolomide to radiation therapy in glioblastoma multiforme remains highly significant with a longer follow-up, and we expect a modest but significant proportion of patients to be long-term survivors," the researchers concluded in an abstract. The study was performed by the EORTC Brain Tumor Group, the Radiation Oncology Group, and the NCIC Clinical Trials Group.
Patient Navigators Tailor Interventions in Minority, Low-Income Populations
Ethnic and racial minorities and low-income patients often encounter barriers to cancer treatment and care, and one proven strategy to reduce such health disparities is to provide ethnically and linguistically appropriate lay patient navigators (LPNs). A new study by researchers at the Centinela Freeman Medical Research Center in Inglewood, CA, identified the most problematic barriers experienced by a group of 493 African American and Latino cancer patients. Strategic intervention by LPNs reduced the average time to overcoming them from 42 days to a single day.
Dr. David Khan and colleagues from the Urban Latino African American Cancer Disparities Project (ULAAC) developed a program tailored to low-income populations using the continuous quality improvement (CQI) approach. Volunteer LPNs were trained and then monitored as they counseled patients in the cohort. Tracking of these interventions and focus groups with LPNs led to the evolution of solutions for the specific barriers faced by this patient group, 60 percent of whom accepted help.
A half dozen barriers recurred among these 300-some patients: transportation was cited most often, with 167 patients needing help; followed by psychosocial issues, financial issues, a fear of cancer, issues related to caregivers, and language issues.
Another goal of the project was to increase participation by these target populations in clinical trials. Using the CQI process, ULAAC found that the navigators possessed biases against clinical trials similar to those in the target population. LPNs were retrained and again intervened with patients, 29 of whom eventually joined clinical trials.
"These patient navigator programs should become an essential part of our health care delivery system," concludes Dr. Khan. The research, funded by NCI's Cancer Disparities Research Partnership Program, was presented last week at the ASTRO annual meeting.
"Boost" Radiation Offers Benefits for Women with Early-Stage Breast Cancer
Women ages 40 and younger with early-stage breast cancer had a reduced risk of cancer returning in the same breast by undergoing an extra dose of radiation after surgery to conserve the breast, followed by standard radiation treatment, researchers said last week at the ASTRO annual meeting in Los Angeles. The additional "boost" dose of radiation reduced the risk of recurrence in the same breast during a 10-year period from nearly 24 percent to 13.5 percent. The effect was seen in women of all ages, though the statistical evidence was strongest among younger women.
The study included 5,500 women who underwent breast-conserving surgeries (lumpectomies) and radiation treatment for stage I and stage II breast cancer. Findings from the study, led by Dr. Harry Bartelink of the Netherlands Cancer Institute, appeared in the August 1 Journal of Clinical Oncology.
The treatment did not appear to help the women live longer. Nonetheless, boost radiation offers some important benefits for these women, according to Dr. Deborah C. Citrin of NCI's Radiation Oncology Branch, who commented on the study. Preventing a recurrence is an important goal after breast-conserving surgery, she said. The boost radiation meant that fewer patients needed a mastectomy because of a recurrence in the same breast, and this helped them avoid the physical and psychological effects of losing a breast.