Category: Thyroid

Monitor: 31

31 - SUBCLINICAL HYPOTHYROIDISM AND RISK OF INCIDENT CANCER AND CANCER MORTALITY: A SYSTEMATIC REVIEW

Thursday, Apr 25
11:30 AM – 12:00 PM

Objective :

Thyroid hormone has been shown to be involved in carcinogenesis via its effects on cell proliferation pathways. The objective of this study was to perform a systematic review and meta-analysis to determine whether subclinical hypothyroidism is associated with the risk of incident cancer and cancer mortality.


Methods : A systematic search was performed on Medline from its inception until November 13th, 2017 using the key search words encompassing thyroid function and cancer.Randomized controlled trials, cohort and case-control studies assessing subclinical hypothyroidism or its treatment and the risk of incident cancer or cancer mortality were identified. Two independent reviewers extracted and performed quality assessment of included studies.


Results : There were no randomized controlled trials that assessed treatment of subclinical hypothyroidism and cancer risk and mortality. A total of 6 cohort and 3 case-control studies met our inclusion criteria. In general, these studies were of medium to good quality. Results from these studies have inconsistent findings in terms of breast, prostate and colon cancer risk. One study assessed the risk of thyroid cancer and found that a higher level of thyroid stimulating hormone (TSH) levels was associated with an increased risk of thyroid malignancy. Two studies found subclinical hypothyroidism to be associated with an increased risk of cancer mortality. One study found subclinical hypothyroidism to be associated with decreased survival compared to normal thyroid function among patients with hepatocellular carcinoma. The presence of heterogeneity prevented the meta-analysis of data.


Discussion : This is the first systematic review that analyzes the effect of subclinical hypothyroidism on the risk of incident cancer and cancer mortality. There is no consistent evidence to suggest that subclinical hypothyroidism is associated with incident breast, prostate and colon cancer risk. Subclinical hypothyroidism may be associated with an increased risk of thyroid malignancy, which may be explained by the role of TSH as a regulator of thyroid cell proliferation. Subclinical hypothyroidism may be associated with an increased risk of cancer mortality. However these findings were from observational studies that did not account for potential protopathic bias whereby patients who are more ill may be less likely to receive treatment for subclinical hypothyroidism.


Conclusion : Subclinical hypothyroidism may be associated with an increased risk of cancer mortality. The number of studies examining thyroid dysfunction and cancer risk and mortality is limited and further studies are needed in this area.

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Oriana Yu

Assistant Professor
Jewish General Hospital
Montreal, Quebec, Canada

Dr. Yu is an Assistant Professor at McGill University and endocrinologist at the Jewish General Hospital.

Juan Gómez-Izquierdo

Family medicine physician
McGill University, Quebec, Canada

Dr. Gomez is a family medicine physician at Lasalle Hospital, Montreal, Quebec, Canada.

Kristian B. Filion

Assistant Professor
McGill University

Dr. Filion is an Assistant Professor in the Departments of Medicine (Division of Clinical Epidemiology) and of Epidemiology, Biostatistics, and Occupational Health at McGill University and a Principal Investigator at the Center for Clinical Epidemiology of the Lady Davis Institute. He obtained his PhD in Epidemiology from McGill's Department of Epidemiology, Biostatistics, and Occupational Health and completed his post-doctoral training in Cardiovascular Epidemiology at the Division of Epidemiology and Community Health of the University of Minnesota.

Jean-Franҫois Boivin

Professor
McGill University

Jean-François Boivin is a physician (Laval, 1973) and a specialist in community medicine (Université de Montréal, 1990). He also holds a doctoral degree in epidemiology (Harvard, 1981). His current research interests include homelessness and health, risk factors and temporal patterns of addiction, and the evaluation of emergency health services.

Dr. Boivin has served on various scientific and policy committees such as the Scientific Council of the Québec Research Institute for Health and Occupational Safety (1997-2001), the Scientific Council of France's Mutuelle générale de l’éducation nationale (1999-2002), and the Advisory Board of the CIHR Institute of Health Services and Policy Research (2004-2008).
He was a consultant and examiner for the Faculty of Medicine of Kuwait (1998-2002).He is currently a member of the Québec Regional Advisory Committee of the Royal College of Physicians and Surgeons of Canada, the Fellowships Affairs of the Royal College, and the Board of Directors of the Canadian Center on Substance Abuse.

Laurent Azoulay

Associate Professor
McGill University

Dr. Laurent Azoulay is an Associate Professor in the Department of Epidemiology, Biostatistics and Occupational Health and Gerald Bronfman Department of Oncology, McGill University. After receiving his PhD in 2007 from the Université de Montréal, he completed a post-doctoral fellowship in pharmacoepidemiology at the Department of Epidemiology, Biostatistics and Occupational Health, McGill University. He then joined the Gerald Department of Oncology as an Assistant Professor in 2009. In 2016, he was promoted to the rank of Associate Professor with a cross-appointment with the Department of Epidemiology, Biostatistics and Occupational Health.

Michael Pollak

Professor
McGill University

Dr. Michael N. Pollak is a clinical oncologist at the Jewish General Hospital, and directs a multi-disciplinary research program related to cancer endocrinology at the Lady Davis Institute for Medical Research. He is an internationally recognized scientist in this field. Clinically, Dr. Pollak specializes in the treatment of hormone-related cancers, and has been the principal investigator on several pivotal clinical trials of new drugs. Dr. Pollak’s laboratory research has focused on the roles of insulin and insulin-like growth factors in cancer biology. His laboratory uses a variety of in vitro and in vivo methods to explore the influences of hormones on cancer behaviour and on cancer risk.

Dr. Pollak has extensive international collaborations in his area of research, and is frequently invited to collaborate in drug development projects led by pharmaceutical industry participants. He reviews papers for leading journals such as the New England Journal of Medicine, Journal of Clinical Investigation, and Nature, and also participates in peer review of research applications submitted to the NIH and other leading funding organizations. He has more than 325 publications to his credit.

One section of his laboratory is devoted to performing specialized hormone assays, and acts as a reference laboratory for leading collaborating epidemiologists worldwide. This laboratory receives blood samples from scientists around the world for analysis.

Dr. Pollak has been recognized by McGill for his contributions to the University's favourable international standing. His 1998 publication in Science is one of the most widely cited Canadian contributions to the cancer research literature. Dr. Pollak has received continuous peer-reviewed funding from Canadian and international sources for more than 20 years. He received one of Quebec’s top scientific honors, the Chercheur national award from the FRSQ.

Oriana Yu

Assistant Professor
Jewish General Hospital
Montreal, Quebec, Canada

Dr. Yu is an Assistant Professor at McGill University and endocrinologist at the Jewish General Hospital.