Biography

Dr. Inskip received a B.S. in biology from Yale College (1976), a M.S. in oceanography and limnology from the University of Wisconsin--Madison (1980) and a Sc.D. in epidemiology from the Harvard School of Public Health (1989). He joined NCI as a Fellow in 1989 and was appointed Staff Fellow in 1990 and Senior Staff Fellow in 1992. He left NCI in 1995 to accept a position as Associate Professor of Epidemiology in the College of Veterinary Medicine at Texas A&M University. He returned to NCI as an Investigator in 1998 and was appointed Senior Investigator in 2004. Dr. Inskip also serves as director of the Radiation Epidemiology Fellowship program. He was appointed Faculty Associate in Epidemiology at Johns Hopkins University in 2001. He serves on the steering committee of the Childhood Cancer Survivor Study, the Late Effects committee of the Children's Oncology Group, the Board of Epidemiology Advisors of the Central Brain Tumor Registry, the Commission on Cancer of the American College of Surgeons Brain/CNS Disease Site Team, and the advisory panel for the INTERPHONE Study, an international study of cellular telephones and cancer that is being coordinated by the International Agency for Research on Cancer. Dr. Inskip received the NCI Special Achievement Award in 1994 and the NIH Merit Award in 2001.

Research Interests

• Etiology of brain tumors
• Cancer risks attributable to medical, environmental and occupational exposures to ionizing radiation
• Genetic determinants of cancer susceptibility

Research

Etiology of Brain Tumors

Brain cancer is among the most aggressive and deadly of cancers, but also one of the most poorly understood. In response to public concerns about risks due to cellular telephones and other recently-introduced environmental exposures, and to pursue other leads concerning possible risk factors, I initiated a comprehensive case-control study of brain tumors in adults. This large, multi-faceted study includes patients newly-diagnosed with glioma, meningioma or acoustic neuroma at any of three hospitals in the U.S. The study design incorporates novel features for the evaluation of occupational exposures, including interviews tailored to individual work histories and provision for follow-up questioning, if necessary, after review of occupational histories by an industrial hygienist. Because of the rapid ascertainment and enrollment of study participants, the proportion of proxy interviews for glioma cases was far lower than in previous case-control studies. Blood samples were collected for use in genetic and mutagen sensitivity assays. Our initial report concerned the possible effects of cellular telephones. We found no evidence of increased risk associated with recent use of cell phones for any of the three tumor types. In subsequent reports, we confirmed and extended previous findings of an apparent reduced risk of glioma among persons with a history of allergies and other immune disorders, found a reduced risk of glioma among left-handed persons relative to right-handed persons, and described an association between season of birth and brain tumor risk. We also observed a reduced risk of glioma associated with early age at menarche or early age at first live birth. Detailed evaluations of risk in relation to occupational exposure to solvents, lead, pesticides and electromagnetic fields are in progress. We also are in the process of evaluating the relation between polymorphisms in a variety of genes and risk of brain tumors and are coordinating these efforts with those of other brain tumor investigators so that we might achieve large enough sample sizes to address possible gene-environment and gene-gene interactions.

Multiple Primary Cancers

I am collaborating with investigators at the University of Minnesota on case-control studies of therapy-related new malignancies of the brain, breast and thyroid gland among 14,050 five-year survivors of childhood cancer. The studies will include detailed radiation dosimetry by a medical physicist and larger numbers of second cancers of the brain, breast and thyroid following childhood cancer than in previous studies. Future analyses will address the possible importance of genetic polymorphisms as modifiers of therapy-related second cancer risks I also have used data collected through NCI's Surveillance, Epidemiology and End Results (SEER) program to address the incidence of multiple primary cancers after childhood cancer and, separately, after a first cancer of the brain or central nervous system (CNS).

Accuracy of Recall of Diagnostic X-rays

In a recent study, colleagues and I evaluated the extent of agreement between self-reported history of medical diagnostic X-rays and histories ascertained from medical records, in the context of a case-control study of thyroid cancer. Results showed poor agreement between exposure histories based on the two sources of information, with a suggestion of greater under-reporting by controls.

Cancer in Chornobyl Clean-up Workers

The hundreds of thousands of men sent to Chornobyl after the reactor accident in 1986 provide a potential opportunity for learning about cancer risks due to protracted exposure to low-dose-rate radiation. I am collaborating with investigators from Estonia, Latvia, Lithuania and Finland on a study of cancer incidence among Chornobyl clean-up workers from Baltic countries that formerly were part of the Soviet Union. Studies to date indicate that radiation doses were lower than initially presumed and that direct health effects of the radiation exposure will be difficult to detect in epidemiologic studies. Although an excess of leukemia or other cancer attributable to radiation was not apparent in our initial analyses, clean-up workers did experience a high rate of suicide in comparison to the general population.

Cancer Mortality among Amateur Radio Operators

Amateur radio operators experience exposure to electromagnetic fields of widely varying frequencies, including radiofrequency (RF) radiation, and their cancer experience is relevant to the hypothesis that RF radiation causes cancer. Some amateur radio operators undertook the hobby many years ago, long enough to accommodate a potentially long cancer induction period. I am a co-investigator on a cohort mortality study of amateur radio operators from California licensed during 1965-1991 (N 110,000) that will clarify whether patterns of mortality differ appreciably between licensed radio amateurs and the general population of California. Unlike previous studies, the present study includes women (N 15,000) as well as men. Cancers of the nervous, hematopoietic and lymphatic systems, plus breast cancer and selected non-cancer outcomes (e.g., amyotrophic lateral sclerosis) are of particular interest.

Keywords

brain cancer, brain tumors, Chornobyl, ionizing radiation, leukemia, nonionizing radiation, radiation, second cancers, thyroid cancer

Selected Publications

• Hatch EE, Linet MS, Zhang J, Fine HA, Shapiro WR, Selker RG, Black PM, Inskip PD. "Reproductive and hormonal factors and risk of brain tumors in adult females." Int J Cancer, In Press.
• Kleinerman RA, Linet MS, Hatch EE, Tarone RE, Black PM, Selker RG, Shapiro WR, Fine HA, Inskip PD. "Self-reported electrical appliance use and risk of adult brain tumors." Am J Epidemiol, In Press.
• Yonehara S, Brenner A, Kishikawa M, Fujii H, Kobuke T, Inskip PD, Ron E, Preston DL, Tokunaga M, Tokuoka S, Mabuchi K. "Clinical and epidemiological characteristics of first primary tumors of the central nervous system and related organs among atomic bomb survivors in Hiroshima and Nagasaki, 1958-1995." Cancer 2004;101:1644-1654.
• Inskip, PD. "Multiple primary cancers involving cancer of the brain and central nervous system as first or subsequent cancer." Cancer 2003;98:562-570.
• Brenner AV, Linet MS, Shapiro WR, Selker RG, Fine HA, Black PM, Inskip PD. "Season of birth and risk of brain tumors in adults." Neurology 2004;63:276-281.
• Rajaraman P, De Roos AJ, Stewart PA, Linet MS, Fine HA, Shapiro WR, Selker RG, Black PM, Inskip PD. "Occupation and risk of meningioma and acoustic neuroma in the United States." Am J Ind Med 2004;45:395-407.
• Berrington A, Ekbom A, Glass AG, Galanti MR, Grimelius L, Allison MJ, Inskip PD. "Comparison of documented and recalled histories of exposure to diagnostic x-rays in case-control studies of thyroid cancer." Am J Epidemiol 2003;157:652-663.
• De Roos AJ, Rothman N, Inskip PD, Linet MS, Shapiro WR, Selker RG, Fine HA, Black PM, Pittman G, Bell D. "Genetic polymorphisms in GSTM1, -P1, -T1 and CYP2E1 and the risk of adult brain tumors in the United States." Cancer Epidemiol Biomark Prev 2003;12:14-22.
• Inskip PD, Tarone RE, Brenner AV, Fine HA, Black PM, Shapiro WR, Selker RG, Linet MS. "Handedness and risk of brain tumors in adults." Cancer Epidemiol Biomark Prev 2003;12:223-225.
• Inskip PD, Tarone RE, Hatch EE, Wilcosky TC, Selker RG, Fine HA, Black PM, Loeffler JS, Shapiro WR, Linet MS. "Laterality of brain tumors." Neuroepidemiology 2003;22:130-138.
• De Roos AJ, Stewart PA, Linet MS, Heineman EF, Dosemeci M, Wilcosky T, Shapiro WR, Selker RG, Fine HA, Black PM, Inskip PD. "Occupation and the risk of adult glioma in the United States." Cancer Causes Control 2003;14:139-150.
• Inskip PD, Tarone RE, Hatch EE, Wilcosky TC, Fine HA, Black PM, Loeffler JS, Shapiro WR, Selker RG, Linet MS. "Sociodemographic indicators and risk of brain tumors." Int J Epidemiol 2003;32:225-233.
• Inskip PD, Devesa SS, Fraumeni JF Jr. "Trends in the incidence of ocular melanoma in the United States, 1974-98." Cancer Causes Control 2003;14:251-257.
• Hill DA, Inskip PD, Shapiro WR, Selker RG, Fine HA, Black PM, Linet M. "Cancer in first-degree relatives and risk of glioma in adults." Cancer Epidemiol Biomark Prev 2003;12:1443-1448.
• Brenner AV, Linet MS, Fine HA, Shapiro WR, Selker RG, Black PM, Inskip PD. "History of allergies and autoimmune diseases and risk of brain tumors in adults." Int J Cancer 2002;99:252-259.
• Inskip PD, Tarone RE, Hatch EE, Wilcosky TC, Shapiro WR, Selker RG, Fine HA, Black PM, Loeffler JS, Linet MS. "Cellular-telephone use and brain tumors." N Engl J Med 2001;344:79-86.
• Inskip PD. "Thyroid cancer after radiotherapy for childhood cancer." Med Pediatr Oncol 2001;36:568-573.
• Inskip PD. "Second cancers following radiotherapy." In: AI Neugut, E Robinson, AT Meadows (editors), Multiple primary cancers. Lippincott ,Williams & Wilkins: Baltimore, 1999, pp 91-135.
• Littlefield LG, McFee AF, Salomaa SI, Tucker JD, Inskip PD, Sayer AM, Lindholm C, Mäkinen S, Mustonen R, Sorenson K, Tekkel M, Veidebaum T, Auvinen A, Boice JD Jr. "Do recorded doses overestimate true doses received by Chernobyl cleanup workers? Results of cytogenetic analyses of Estonian workers by fluorescence in situ hybridization." Radiat Res 1998;150:237-249.
• Inskip PD, Hartshorne MF, Tekkel M, Rahu M, Veidebaum T, Auvinen A, Crooks LA, Littlefield LG, McFee AF, Salomaa S, Mäkinen S, Tucker JD, Sorenson KJ, Bigbee WL, Boice JD Jr. "Thyroid nodularity and cancer among Chernobyl clean-up workers from Estonia." Radiat Res 1997;147:225-235.
• Rahu M, Tekkel M, Veidebaum T, Pukkala E, Hakulinen T, Auvinen A, Rytömaa T, Pukkala E, Inskip PD, Boice JD Jr. "The Estonian study of Chernobyl clean-up workers: II. Incidence of cancer and mortality." Radiat Res 1997;147:653-657.

Collaborators

DCEG Collaborators

• Elizabeth Bluhm, M.D.; Alina Brenner, Ph.D.; Rochelle Curtis, M.S.; Deirdre Hill, Ph.D.; Ruth Kleinerman, M.S.; Martha Linet, M.D.; Preetha Rajaraman, M.S.; Cecile Ronckers, Ph.D.; Alice Sigurdson, Ph.D.; Patricia Stewart, Ph.D.; Nathaniel Rothman, M.D.; Mustafa Dosemeci, Ph.D.; Joseph Coble, Ph.D.; Kenneth Cantor, Ph.D.; Claudine Samanic, Ph.D.; Wen-Yi Huang, Ph.D.; Dilys Parry, Ph.D.; Regina Ziegler, Ph.D.

Other NCI Collaborators

• Howard Fine, M.D.

Other Scientific Collaborators

• Anssi Auvinen, M.D.; University of Tampere, Tampere, Finland
• Peter Black, M.D.; Brigham and Women's Hospital, Boston, MA
• John Boice, Jr., Sc.D.; International Epidemiology Institute; Rockville, MD
• Anneclaire De Roos, Ph.D.; Fred Hutchinson Cancer Research Center, Seattle, WA
• Anders Ekbom, M.D.; Karolinska Institute, Stockholm, Sweden
• Timo Hakulinen, Ph.D.; Finnish Cancer Registry, Helsinki, Finland
• Per Hall, M.D.; Karolinska Institute, Stockholm, Sweden
• Elizabeth Hatch, Ph.D.; Boston University, Boston, MA
• Juozas Kurtainitis, Ph.D.; Lithuanian Cancer Registry, Vilnius, Lithuania
• L. Gayle Littlefield, Ph.D.; Oak Ridge Institute for Science and Medicine, Oak Ridge, TN (retired)
• Ann Mertens, Ph.D.; University of Minnesota, Minneapolis, MN
• Joseph Neglia, M.D.; University of Minnesota, Minneapolis, MN
• Mati Rahu, Ph.D.; Institute of Clinical and Experimental Medicine, Tallinn, Estonia
• Leslie Robison, Ph.D.; University of Minnesota, Minneapolis, MN
• Robert Selker, M.D.; Western Pennsylvania Hospital, Pittsburgh, PA
• William Shapiro, M.D.; St. Joseph's Hospital and Medical Center, Phoenix, AZ
• Aivars Stengrevics, M.D.; Latvian Oncological Centre, Riga, Latvia
• Marilyn Stovall, M.S.; The University of Texas M. D. Anderson Cancer Center Houston, TX
• Robert Tarone, Ph.D.; International Epidemiology Institute; Rockville, MD
• Mare Tekkel, Ph.D.; Institute of Clinical and Experimental Medicine, Tallinn, Estonia
• Toomas Veidebaum, Ph.D.; Institute of Clinical and Experimental Medicine, Tallinn, Estonia
• Timothy Wilcosky, Ph.D.; Research Triangle Institute, Research Triangle Park, NC
• Yutaka Yasui, Ph.D.; Fred Hutchinson Cancer Research Center, Seattle, WA