Calcium Supplements Offer Prolonged Protection Against Colorectal Adenomas in High-Risk Patients
Previous studies have shown that people with noncancerous colorectal tumors called adenomas who take calcium supplements for 4 years can reduce their risk of an adenoma recurrence. A new study shows that the protective effect of those supplements lasts for up to 5 years after stopping supplementation.
In the Calcium Polyp Prevention Study, 930 people with a recent adenoma were randomly assigned to receive 4 years of daily 1200-milligram calcium supplements or a placebo. The study revealed that those assigned to calcium supplements had a 17 percent lower relative risk of an adenoma recurrence than those who got the placebo.
In the new study, Maria V. Grau, M.D., and John A. Baron, M.D., of Dartmouth Medical School, and colleagues followed 822 of the patients from that trial after the end of the treatment. Their aim was to compare the risk of recurrence among participants who had taken calcium with the risk among those who had taken a placebo.
The researchers found that, in the first 5 years after the end of the treatment, people in the calcium group continued to have a lower risk of adenomas than those in the placebo group: 31.5 percent of people who had taken calcium had recurrences compared with 43.2 percent of those originally in the placebo group. However, after 5 years, this protective effect disappeared.
"Our study provides further evidence of the potential of calcium as a chemopreventive agent against colorectal adenomas among individuals with a history of these tumors," the authors write. "Our data indicate that, in these patients, the protective effect of calcium may extend for up to 5 years after the cessation of active treatment."
"Where do we go from here--and, more important, what public health recommendations related to calcium do we provide for risk reduction of colorectal cancer?" ask editorial writers María Elena Martínez, Ph.D., and Elizabeth T. Jacobs, Ph.D., of the Arizona Cancer Center in Tucson. They note that current guidelines recommend that people simply consume recommended levels of calcium (1000 mg/day for adults up to age 50 years and 1200 mg/day for those older than 50 years). "Because no protection for colorectal cancer is apparent at higher levels of calcium intake, this recommendation is justified," they write.
Contact:
- Article: Sue Knapp, Dartmouth Medical School Communications Office, 603-646-3661, sue.knapp@dartmouth.edu
- Editorial: María Elena Martínez, Ph.D., Arizona Cancer Center, emartinez@azcc.arizona.edu
Nutrient Supplements Not Associated with Reduced Gastric Cancer Risk
Taking antioxidants, compounds such as vitamins A and C and beta-carotene that protect cells from damage in tissue culture, does not reduce the risk of gastric cancer, a randomized trial finds.
Environmental factors play an important role in gastric cancer; for example, infection with the bacterium Helicobacter pylori is a known cause of gastric cancer. Some studies have suggested that a diet rich in fruit and vegetables decreases the risk of gastric cancer, perhaps because such foods contain antioxidants.
To determine the effect of antioxidant supplements on gastric cancer risk, Martyn Plummer, of the International Agency for Research on Cancer, and colleagues conducted a randomized clinical trial among 1980 people in Tachira State, Venezuela, whose population is at high risk of gastric cancer. Participants were randomly assigned to receive a placebo or a combination of the antioxidants vitamin C, vitamin E, and beta-carotene.
Over the 3 years of the study, all participants had several gastroscopies, or examinations of the stomach using a thin, lighted tube. During the gastroscopies, doctors took small tissue samples from specific areas of the stomach. The researchers found that antioxidant supplementation did not make a difference in the progression rate or regression rate of precancerous gastric lesions. "Supplementation with antioxidant micronutrients is not an effective tool for gastric cancer control in this high-risk population," the authors conclude.
"Disappointingly, this must be considered a negative trial," writes editorialist Philip R. Taylor, M.D., Sc.D., of the National Cancer Institute. "The way forward will require continued etiologic research to identify new modifiable factors, such as bioactive food components or other alterable environmental factors, as well as a search for beneficial associations with drugs. However, this overall effort should continue to emphasize randomized controlled trials as the most powerful and valid approach for testing specific prevention strategies and follow lessons and leads from the first generation of cancer prevention interventions."
Contact:
- Article: Martyn Plummer, International Agency for Research on Cancer, +33 (0)4 72 73 84 46, plummer@iarc.fr
- Editorial: National Cancer Institute Media Relations Branch, 301-496-6641, ncipressofficers@mail.nih.gov
Allergy Not Associated with Development of Non-Hodgkin Lymphoma
Allergies and allergy-related conditions are not likely related to non-Hodgkin lymphoma risk, according to a new study. Some previous studies had suggested that allergies might protect against this cancer.
The body's allergic reaction to a substance includes an increase in specific types of immune cells. Some researchers have observed a possible association between allergies and reduced cancer risk and suggested that the allergy-induced immune response also might inhibit tumor growth. Non-Hodgkin lymphoma, a cancer of the immune system, is particularly sensitive to immune system changes, and earlier studies reported a decreased risk of this cancer among people with allergic rhinitis, hay fever, or food allergies. However, several other studies found no such association.
Mads Melbye, M.D., Ph.D., of the Statens Serum Institut in Copenhagen, and colleagues decided to investigate the relationship more thoroughly. First they looked at a retrospective study of 3,055 patients with non-Hodgkin lymphoma and 3,187 control patients without the disease. Questionnaire data and blood samples were collected after people were diagnosed with non-Hodgkin lymphoma.
Initially they found that people who had ever had hay fever had a reduced risk of non-Hodgkin lymphoma. Specifically, people with high levels of the antibodies specific for hay fever had a 32 percent lower risk of NHL than people who didn't have hay fever. However, further investigation revealed that among patients with cancer, the more the cancer had spread throughout the body, the lower the antibody levels were. This suggested to the researchers that allergic responses might be dampened by having non-Hodgkin lymphoma.
"Our finding of a lower prevalence of allergic rhinitis among case patients with non-Hodgkin lymphoma than among population control subjects may reflect a recent decline in clinical manifestations of allergic conditions as a result of underlying non-Hodgkin lymphoma disease," the authors write.
The authors then studied the association in a prospective case-control population; blood samples were available for 198 lymphoma patients before they developed their cancer and for 594 control patients. When they looked at antibody levels in people before they developed cancer, they found that there was no association between allergy and the development of non-Hodgkin lymphoma.
"Allergy may not be causally associated with the risk of non-Hodgkin lymphoma. The inverse association observed in some case-control studies may arise because non-Hodgkin lymphoma suppresses the immunologic response to allergens," the authors write.
Contact: Mads Melbye, M.D., Ph.D., Statens Serum Institut, Copenhagen, +45-32683163 or +45-40111185, mme@ssi.dk
Gum Disease Associated with Pancreatic Cancer Risk
Having gum disease is associated with an increased risk of pancreatic cancer, according to a new study. However, the authors caution that further studies are necessary to determine whether the relationship is causal.
There are few known risk factors for pancreatic cancer, including cigarette smoking and chronic pancreatitis. The latter is marked by inflammation, suggesting that inflammation may be involved in the initiation or progression of pancreatic cancer. People with periodontal (gum) disease usually have high levels of certain markers of systemic inflammation. Two earlier studies had found an association between tooth loss (periodontitis is the primary cause of tooth loss in adults) and pancreatic cancer.
In the new study, Dominique S. Michaud, Sc.D., of the Harvard School of Public Health, and colleagues studied the relationship between periodontitis and tooth loss and the subsequent risk of pancreatic cancer in more than 50,000 men in the Health Professionals Follow-Up Study. They found that a history of periodontal disease was associated with an increased risk of pancreatic cancer; 25 pancreatic cancer cases would be expected per 100,000 men, but having periodontal disease increased that rate to 61 per 100,000 men. Cumulative tooth loss was not associated with pancreatic cancer.
"Given our limited understanding of pancreatic cancer etiology, we believe that further investigation into this relation and the role of systemic inflammation in pancreatic carcinogenesis is warranted," the authors write.
Contact: Todd R. Datz, External Communications, Harvard School of Public Health, 617-432-3952, tdatz@hsph.harvard.edu
Biomarker May Forecast Probability of Recurrence in Breast Cancer
Testing tumors for a protein called Ki67 after short-term treatment for breast cancer may help doctors predict whether a patient is likely to have a recurrence, a new study shows.
The presence of Ki67 indicates tumor cell growth, and researchers have used Ki67 measurements as a marker of whether experimental cancer treatments effectively stop cancer growth. To determine whether this marker also indicates a clinical benefit, such as improved recurrence-free survival, Mitch Dowsett, Ph.D., of The Royal Marsden Hospital, in London, and colleagues studied Ki67 levels in tumor biopsy samples taken before and after 2 weeks of presurgical treatment with anastrozole, tamoxifen, or both drugs from 158 women with hormone receptor-positive breast cancer.
The researchers found that higher Ki67 expression after 2 weeks of presurgical therapy was associated with worse recurrence-free survival. There was no association between the Ki67 level before therapy and recurrence-free survival. They also found that larger tumor size before therapy and lower estrogen receptor level after 2 weeks of treatment were associated with worse recurrence-free survival.
"Measurements of tumor Ki67 expression after short-term endocrine treatment may improve the prediction of recurrence-free survival for breast cancer patients," the authors conclude. They add that larger studies are needed to confirm the results before such testing is made widely available to patients.
Contact: Catherine O'Mara, Press & PR Officer, the Royal Marsden NHS Foundation Trust, + 44 20 7808 2605, catherine.o'mara@rmh.nhs.uk
Also in the January 17 JNCI:
- No benefit to increasing dose intensity of chemotherapy in osteosarcoma, study finds, http://www.eurekalert.org/emb_releases/2007-01/jotn-bt011107.php
- Study identifies common flaws in oncology microarray studies, http://www.eurekalert.org/emb_releases/2007-01/jotn-ic011107.php
Note: The Journal of the National Cancer Institute is published by Oxford University Press and is not affiliated with the National Cancer Institute. Attribution to the Journal of the National Cancer Institute is requested in all news coverage. Visit the Journal online at http://jncicancerspectrum.oxfordjournals.org/.
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