Biography

Dr. Ron received an M.P.H. from the Yale University School of Public Health and a Ph.D. in epidemiology from the Tel Aviv University School of Medicine. She conducted postdoctoral research at the Chaim Sheba Medical Center in Israel. Dr. Ron joined the NCI as a Visiting Associate in 1986, spent a year at the Radiation Effects Research Foundation in Hiroshima, Japan in 1991, and was appointed to head the Branch in 1997. She received the NIH Director's Award for developing an international program in radiation and thyroid cancer. Dr. Ron served as the Women Scientists' Advisor for DCEG from 1994 to 1996. She is an associate editor of Radiation Research, a consultant to the U.N. Subcommittee on the Effects of Ionizing Radiation, and an advisor to the Scientific Committee on Risk to Thyroid from Ionizing Radiation of the National Council on Radiation Protection and Measurements.

Research Interests

Ionizing Radiation and Cancer

To address concerns about the health effects of radiation exposure, we are evaluating the risk of radiation-associated tumors in the medical, occupational, and environmental settings. In addition, we are examining biologic mechanisms related to radiation carcinogenesis. Our research focuses on quantifying the tumorigenic risk of external (x and gamma ray) and internal (iodine 131) radiation, the carcinogenic effects of protracted or fractionated radiation exposure, and the etiology of thyroid disease.

Carcinogenic Effects of External Radiation

In collaboration with the Radiation Effects Research Foundation in Hiroshima, we are studying cancer incidence in approximately 90,000 Japanese atomic bomb survivors. We found that for some organs or tissues, radiation related risk varies by histological type. An increased risk was observed for basal cell carcinoma of the skin, but not for squamous cell carcinoma. The dose response relationship for basal cell carcinoma was strongest among persons who were exposed to the radiation in early childhood. No interaction was seen between exposure to ultraviolet radiation and radiation from the bombings. We also found a significant dose response relationship for neurilemmomas, all central nervous system (CNS) tumors combined, and pituitary tumors, but not for gliomas. Age at exposure was not a significant risk modifier for the CNS tumors.

In another study, we evaluated cancer incidence in a cohort of almost 1,000 Israeli women treated with radiotherapy for infertility. The majority of the women were irradiated to both the ovaries and pituitary gland. No significant excess or deficit occurred for any individual cancer type, although a non significant 60% increase in colon cancer was observed.

Radioactive Iodines

Radioactive Radioactive iodines are widely used in medicine and can pose a health threat when accidently released into the environment by nuclear power plants. In an attempt to clarify the impact of radioiodines in carcinogenesis, we are studying several cohorts of patients exposed to diagnostic or therapeutic I 131. In an investigation of cancer mortality among almost 35,000 hyperthyroid patients, we found that over 50% were deceased by the end of follow-up. High dose I 131 treatment was not linked to an overall increased risk of death from solid tumors or leukemia. Although mortality related to thyroid cancer was significantly elevated, the number of radiation associated thyroid cancer deaths was small. We plan to conduct a pooled analysis of thyroid and other cancer risks after the ongoing medical I-131 studies are completed. In another project, we are investigating thyroid disease among persons potentially exposed to I 131 emissions from a nuclear facility in the Russian Federation. Preliminary data suggest that childhood exposure to I-131 emissions may pose a small increased risk of developing thyroid neoplasia.

Protracted Radiation Exposures

In a collaboration with investigators from the Russian Federation, the United States, and Japan, we are investigating the relationship between cancer mortality and protracted radiation exposure in occupational and environmental settings. The investigation includes nearly 20,000 workers at the Mayak nuclear facility in Ozyorsk, Russia, who were exposed to external and/or internal radiation, and about 30,000 persons living in villages near a river polluted by radioactive wastes from the facility. Preliminary results suggest dose related increases in solid cancers and leukemia among long term Mayak workers who experienced chronic exposures to external radiation.

Thyroid Disease

Thyroid Disease Radiation is the only well-defined cause of thyroid cancer. To elucidate other etiologic factors, we are collaborating in an international pooled analysis of 14 case control studies of thyroid cancer. The analysis includes over 2,500 thyroid cancer cases and 4,000 controls. Results thus far indicate that risks associated with menstrual and reproductive factors are generally weak, but appear stronger among women diagnosed with thyroid cancer at younger ages. A moderately elevated risk in current oral contraceptive users was observed, but disappeared 10 or more years after usage stopped. The results also suggest that thyroid cancer incidence is related to height and weight at time of diagnosis. Consumption of fish was not significantly associated with thyroid cancer risk. In iodine deficient areas, high fish intake may protect against risk of thyroid cancer.

Keywords

atomic bomb survivors, central nervous system tumors (CNS), I-131, ionizing radiation, radiation, skin cancer, thyroid cancer

Selected Publications

• Ron E, et al. "Cancer mortality following treatment for adult hyperthyroidism." Cooperative Thyrotoxicosis Therapy Follow up Study Group. JAMA 1998; 280:347-355.
• Ron E, et al. (editors). Uncertainties in radiation dosimetry and their impact on dose-response analyses. NIH publication no. 99-4541, 1999.
• Brenner DJ, et al. "Second malignancies in prostate carcinoma patients after radiotherapy compared with surgery." Cancer 2000; 88:398-406.
• Schafer DW, et al. "Thyroid cancer following scalp irradiation: a reanalysis accounting for uncertainty in dosimetry." Biometrics 2001; 57:689-697.

Collaborators

DCEG Collaborators

• Andre Bouville, Ph.D.; Rochelle Curtis, M.A.; Michele Doody, M.P.H.; Ethel Gilbert, Ph.D.; Gloria Gridley, M.S.; Ruth Kleinerman, M.P.H.; Charles Land, Ph.D.; Jay Lubin, Ph.D.; Kiyohiko Mabuchi, M.D., Dr.P.H.; Steven Mark, M.D., Sc.D.; Dilys Parry, Ph.D.; Alice Sigurdson, Ph.D

Other NCI Collaborators

• Jeffrey Struewing, M.D.

Other Scientific Collaborators

• Anssi Auvinen, M.D., Ph.D., University of Tampere, Tampere, Finland
• David Brenner, D.Sc.. Columbia University, New York, NY
• Ray Carroll, Ph.D., Texas A&M University, College Station, TX
• Silvia Franceschi, M.D., International Agency for Research on Cancer, Lyon, France
• Per Hall, M.D., Karolinska Institute, Stockholm, Sweden
• Jose Iscovich, M.D., Israel Tumor Registry, Jerusalem, Israel
• Nina Koshurnikova, M.D., Ph.D.; Natalia Shilnikova, Ph.D., Biophysics Institute Branch 1, Ozyorsk, Russia
• Mira Kossenko, M.D., Urals Research Center for Radiation Medicine, Chelyabinsk, Russia
• Carlo La Vecchia, M.D.; Eva Negri, Ph.D., “Mario Negri” Pharmacology Research Institute, Milan, Italy
• Dale Preston, Ph.D., Radiation Effects Research Foundation, Hiroshima, Japan
• Arthur Schneider, M.D., Ph.D., University of Illinois, Chicago, IL
• Marilyn Stovall, Ph.D., M.D., MD Anderson Cancer Center of the University of Texas, Houston, TX