Rare Form of Cervical Cancer Also Linked to HPV Infection

Infection with human papillomavirus (HPV) was found to be the key risk factor for cervical adenocarcinoma (AC), a type of cervical cancer less common than squamous cell carcinomas (SCC), in an analysis of eight case control studies from Africa, South America, and Southeast Asia published in the March 1 Journal of the National Cancer Institute (JNCI).

Approximately 70 percent of the cases of SCC are attributable to infection with HPV 16 or 18. Results from the study by researchers led by Dr. Xavier Castellsagué of the Institut Català d'Oncologia in Barcelona have now demonstrated that approximately 85 percent of AC cervical cancer can be explained by infection with these two types of HPV. AC accounts for about 20 percent of cervical cancers diagnosed in the United States.

In an editorial, Drs. Allan Hildesheim of NCI's Division of Cancer Epidemiology and Genetics and Amy Berrington de González of Johns Hopkins University, concur with the researchers in noting the implications of the findings in light of the recent successes in clinical trials of vaccines against the two HPV strains. This suggests that "it would not be unrealistic to expect rates of AC to drop in future years, as screening continues to be improved, HPV testing is incorporated into (or in some instances replaces) Pap smear screening programs, and prophylactic HPV 16/18 vaccines become available for broad use," they note.

A New Animal Model for Tumor Angiogenesis

The angiogenic switch, which enables tumor cells to recruit their own vascular system and grow beyond 1 to 2 millimeters, is a key requirement for cancer metastasis. A new study led by investigators from Harvard Medical School published in the March 1 JNCI has produced cell lines from a mouse model of spontaneous angiogenesis in tumor xenografts that can be used for in-depth studies of the angiogenic process.

The investigators injected mice with nonangiogenic human breast cancer, osteosarcoma, or glioblastoma cells. When xenograft implants spontaneously became angiogenic, the cells were harvested and cultured into new cell lines. These new cell lines formed palpable tumors within 20 days of injection compared with means of 119, 238, and 226 days for the three nonangiogenic cell lines. No significant differences in cell proliferation rates had been noted between the nonangiogenic and angiogenic cell lines in vitro.

They then used this model to analyze the possible role of several proteins in the angiogenic switch, including thrombospondin-1, a known angiogenesis inhibitor. The investigators found that nonangiogenic cells in all three cancer types secreted significantly higher levels of thrombospondin-1 than did their angiogenic counterparts.

"We are learning more and more about these angiogenic factors," says Dr. Giovanna Tosato, an investigator with NCI's Center for Cancer Research (CCR) who authored an accompanying editorial. "There are drugs already approved that inhibit angiogenesis, and there are many more on the horizon. So we may be able to turn or change tumors that have switched and have become 'bad' into others that may 'stay still' for a long time."

Study Links Meat Consumption to Gastric Cancer

A new analysis of participants in a large European cohort study shows a significant association between a type of gastric cancer and meat consumption, but primarily in men and women infected with the bacteria H. pylori.

The study, published in the March 1 JNCI, involved more than 521,000 men and women in the European Prospective Investigation into Cancer and Nutrition (EPIC) cohort. With a mean follow-up of 6.5 years, there were 330 cases of gastric adenocarcinoma and 65 cases of esophageal adenocarcinoma.

The researchers reported a statistically significant positive association between total meat intake - which includes fresh red meat, processed red meat, and poultry - and cancer in the lower portion of the stomach, called gastric noncardia cancer. Every 150-gram increase in total meat intake showed a 2.5-fold increase in risk. A statistically significant positive association was also seen with red meat intake and processed meat intake.

"All of these associations seemed to be restricted to the H. pylori-infected subjects," the researchers, led by Dr. Carlos A. Gonzalez from the Catalan Institute of Oncology in Barcelona, Spain, wrote. There was no such association seen for gastric cardia cancer, which occurs in the top 2 to 3 centimeters of the stomach. There also was a nonstatistically significant association between total meat intake or processed red meat intake and esophageal adenocarcinoma, the cancer with the most quickly increasing incidence rate in the United States.

H. pylori infection is considered a risk factor for gastric cancer. But the authors argued that "other, unknown factors must play a role in [gastric] cancer risk because, although the intake of red meat has increased in most European countries during the last decades, the prevalence of H. pylori infection and the incidence of gastric noncardia cancer have decreased over the same period."

FDA Approves Erbitux for Head and Neck Cancer

On March 1, the Food and Drug Administration (FDA) announced the approval of Erbitux (cetuximab) for use in combination with radiation therapy to treat patients with unresectable squamous cell cancer of the head and neck. Cetuximab is the first drug approved for this cancer that has shown a survival benefit in this population. Cetuximab was also approved for use alone to treat patients whose head and neck cancer has spread despite the use of standard chemotherapy.

Cetuximab received a priority review and is the first drug approved to treat head and neck cancer since methotrexate became available in the 1950s. Approval of the drug in combination with radiation therapy was based on a study that showed it prolonged survival by 20 months compared with treatment with radiation alone. Approval of cetuximab monotherapy was based on evidence of tumor shrinkage in 13 percent of patients, lasting an average of 6 months.