Other highlights in the October 5 JNCI

A new study has found little or no evidence that being breast-fed as an infant is associated with cancer risk as an adult.

Exposures to environmental factors in infancy may influence cancer risk later in life. For example, breast feeding is associated with height and insulin-like growth factor 1 (IGF-1) levels in later childhood, and height and IGF-1 levels have been associated with the risk of some adult cancers. However, studies that relate having been breast-fed with later risks of cancer have been inconclusive.

To determine the associations between breast-feeding during infancy and adult cancer incidence and mortality, Richard M. Martin, B.M., Ph.D., of the University of Bristol in England, and colleagues analyzed 65 years of follow-up data from the Boyd Orr cohort--a group of nearly 5,000 subjects from Britain who were surveyed originally in 1937 to 1939 at ages 0 to 19--and also conducted a meta-analysis of this data and other published studies.

Neither analysis showed an association between having been breast-fed and incidence of either all cancers or of cancer at specific sites, including breast cancer. The meta-analysis did show a reduced risk of premenopausal breast cancer in breast-fed women, but the authors caution that the observed reduction could have arisen by bias or chance.

Contact: Cherry Lewis, Research Communications Manager, University of Bristol, +44 (0)117 928 8086, cherry.lewis@bristol.ac.uk

Red Meat Associated With Pancreatic Cancer Risk

High consumption of red and processed meats--but not fat or cholesterol--is associated with an increased risk of pancreatic cancer, according to a new study.

Nearly 32,000 Americans were diagnosed with pancreatic cancer last year, and most of them will die from the disease. The 5-year survival rate is less than 5%. Identification of risk factors for the disease has become a part of prevention efforts. Some dietary studies have identified meat, dairy product, and egg consumption as potential risk factors, but the results have been mixed.

To investigate associations between intake of meat, other animal products, fat, and cholesterol and pancreatic cancer risk, Ute Nöthlings, Dr.P.H., of the Cancer Research Center of Hawaii in Honolulu, and colleagues analyzed data from the prospective Multiethnic Cohort Study. During 7 years of follow-up, 482 cases of pancreatic cancer were diagnosed among the more than 190,000 participants.

Participants in the highest quintile of processed meat intake had a 68% increased risk of pancreatic cancer compared with those in the lowest quintile. The yearly incidence rate of pancreatic cancer was 41.3 cases per 100,000 people in the highest quintile compared with 20.2 cases per 100,000 in the lowest quintile. Intakes of pork and red meat were both associated with 50% increased risks of pancreatic cancer when comparing the highest and lowest quintiles. The authors found no associations between intakes of poultry, fish, dairy products, eggs, total fat, saturated fat, or cholesterol and pancreatic cancer risk. They suggest that because fat is not likely to contribute to the mechanism underlying the findings for meat consumption, carcinogenic substances resulting from meat preparation techniques might be responsible for the increase in pancreatic cancer risk.

Contact: Sharon Shigemasa, Cancer Research Center of Hawaii, 808-586-3011, Sharon@crch.hawaii.edu

Study in Mice Finds Response to Cancer Vaccine Enhanced by Chemotherapy

A study of a cancer vaccine in mice has found that the vaccine induces a tumor-specific immune response that is enhanced when used with chemotherapy regimens that include 5-fluorouracil (5-FU).

Chemotherapy drugs such as 5-FU inhibit the activity of the enzyme thymidylate synthase (TS), which is necessary for DNA synthesis and cell replication and is often overexpressed in cancer cells. Tumor cells usually respond to the drug exposure by temporarily enhancing the production of this enzyme. Tumor cells can become resistant to 5-FU if they are able to overproduce TS or have mutated enzyme. To determine whether this treatment limitation could be overcome using a peptide vaccine, Pierpaolo Correale, M.D., Ph.D., and Maria Cusi, Ph.D., of Siena University in Italy, and colleagues evaluated mice vaccinated with a peptide (TS/PP) designed to target the enzyme TS.

They report that, in mice vaccinated with TS/PP and subsequently inoculated with TS-expressing lymphoma cells, tumor formation was either delayed or prevented, especially when the mice were also treated with 5-FU. The authors conclude that TS/PP could induce a tumor-specific response in mice and suggest that such a vaccine could have clinical application in humans.

In an editorial, Carmen J. Allegra, M.D., of the Network for Medical Communication Research in North Potomac, Md., and Richard W. Childs, M.D., of the National Heart, Lung, and Blood Institute, note that this vaccine approach, if translatable into the management of human cancer, would be remarkable but caution that it requires additional preclinical study of potential barriers to clinical use in patients.

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