Linet Retires After 33 Years at NCI

Dr. Martha Linet, senior investigator and former chief of the Radiation Epidemiology Branch (REB) in NCI’s Division of Cancer Epidemiology and Genetics (DCEG), retired in January after 33 years of service.

Linet was an international leader in epidemiology and expert on the etiology of pediatric and adult leukemia, lymphoma and brain tumors, as well as the health effects of ionizing and non-ionizing radiation and benzene exposure. She is the author of over 400 papers, along with multiple chapters, monographs and books. 

“Dr. Linet’s ability to design and direct large and complex epidemiologic field studies has resulted in several critical discoveries that improved public health,” said DCEG director Dr. Stephen Chanock. “Her high-impact research clarified risks of cancer and other radiation-related diseases and led to ground-breaking discoveries in the etiology of hematopoietic and central nervous system neoplasms.”

Linet was instrumental in the design and leadership of the U.S. Radiologic Technologists Study, which identified excess risk of cancer and other adverse health outcomes among a nationwide cohort of 146,022 technologists. She and her colleagues recently launched studies of exposures to medical professionals from emergent technologies rapidly growing in use: fluoroscopically guided interventional procedures and nuclear medicine procedures. Results from these investigations emphasized the need for ongoing vigilance for radiation workers and provided a valuable body of research contributing to guidelines for low dose radiation exposures.  

Her research on the causes of leukemia and lymphoma includes a large occupational cohort study of more than 100,000 benzene-exposed workers in over 700 factories in China. Through this large, binational effort, Linet and colleagues found that exposed workers were at higher risk of developing acute myeloid leukemia and myelodysplastic syndromes (AML/MDS) and clarified the benzene and AML/MDS exposure-response relationship according to exposure windows, age at first exposure and other occupational characteristics. The findings from over 30 years of studies by Linet and her collaborators from the United States and China informed U.S. Environmental Protection Agency rules limiting the benzene content in gasoline and requiring controls on passenger vehicles and portable fuel containers, as well as international occupational standards.  

To address public concern over exposure to magnetic fields from power lines and electrical appliances, Linet led a collaborative NCI-Children’s Oncology Group case-control study of pediatric leukemia. The study found that neither high measured residential magnetic field levels (except possibly magnetic field levels greater than 0.4 microtesla) nor high wire code levels (a proxy measure for close distance of residence to power lines) were associated with significantly increased risks of the most common type of childhood leukemia, acute lymphoblastic leukemia (ALL). This information formed the basis of judicial rulings in the United Kingdom and elsewhere on the potential health effects of these exposures. Importantly, this study identified new factors associated with reduced risk of childhood ALL: breast-feeding, daycare attendance, and vaccination to protect against influenza B.

She also investigated radiofrequency radiation exposure among adults from cell phone use, resulting in one of the earliest studies of this exposure within a large hospital-based case-control study. Linet and colleagues observed no association between risk of brain tumors (gliomas, meningiomas, and acoustic neuromas) and cumulative use, duration, or minutes per day of use of cellular telephones.

Linet has been a driving force in several international research consortia, including the International Lymphoma Epidemiology Consortium (InterLymph) and the International Childhood Cancer Consortium. Her efforts to help establish these consortia paved the way for a new era of large-scale international collaborations, leading to new insights into cancer etiology. 

For 12 years, Linet served as chief of REB (2002-2014). Under her leadership, REB conducted critical research and provided advice to the U.S. government and international organizations concerning the health risks associated with exposure to medical, occupational and environmental sources of radiation, including nuclear fallout from weapons testing and nuclear accidents, as well training the next generation of radiation science researchers.  

In addition, she chaired the DCEG promotions and tenure review panel (2014-2019), ushering through scores of hiring and promotion nominations for the division. She also served on multiple tenure-track investigators' mentoring committees and mentored many postdoctoral fellows and trainees. 

REB chief Dr. Amy Berrington said, “Martha fostered a special, supportive and flexible environment for the next generation of scientists—in particular women scientists—in DCEG who aspire to conduct important research whilst raising a family. We are forever grateful to her for making it possible for so many of us to thrive."

Linet devoted herself to 45 national and international committees, two editorial boards and dozens of journal review teams. She recently completed 6 years as a member the National Academy of Sciences nuclear and radiation studies board. She is a long-time member of the editorial board of the Journal of the National Cancer Institute and was a 10-year member of the editorial board of the American Journal of Epidemiology. During 2004-2005, Linet was president of the American College of Epidemiology, where she was successful in reinvigorating the leadership of the association with a new cohort of junior investigators.

Linet recently led the development of an American Academy of Pediatrics technical report on “Pediatric Considerations Before, During and After Radiation/Nuclear Emergencies.” She authored The Leukemias: Epidemiologic Aspects, an internationally recognized text in the field, and is a co-editor of the recently published fourth edition of Cancer Epidemiology and Prevention, the most authoritative and encyclopedic text on cancer's causes, incidence, mortality and survival patterns. Among her many honors are the HHS Career Achievement Award, numerous awards from the NCI and NIH, including NIH Merit and Director’s Awards, NCI Merit Awards, the NCI Mentoring Award, and induction into both the Johns Hopkins Society of Scholars and the American Epidemiological Society. 

Upon retirement, Linet will continue to support research and mentorship in DCEG as an NIH scientist emerita.