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BioMed Research International
Volume 2013, Article ID 748178, 9 pages
Review Article

Cancer Morbidity in Rheumatoid Arthritis: Role of Estrogen Metabolites

1Department of Clinical Biochemistry, College of Medicine, King Khalid University, Abha 641, Saudi Arabia
2Institute of Infection and Immunity, Cardiff University School of Medicine, Henry Wellcome Building, Heath Park, Cardiff CF14 4XN, UK

Received 24 April 2013; Accepted 17 August 2013

Academic Editor: Shigeru Kotake

Copyright © 2013 Wahid Ali Khan and Mohd Wajid Ali Khan. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Estrogen metabolites have been implicated in rheumatoid arthritis (RA) and cancer, although the mechanism remains unestablished. Some estrogen metabolites, which are used for the assessment of cancer risk, play an important role in RA. The pathways by which malignancies associated with RA remain elusive. Possible mechanism involves enzymatic or nonenzymatic oxidation of estrogen into catecholestrogen metabolites through semiquinone and quinone redox cycle to produce free radicals that can cause DNA modifications. Modifications of DNA alter its immunogenicity and trigger various immune responses leading to elevated levels of cancer and RA antibodies. However, the role of different estrogen metabolites as a mediator of immune response cannot be ruled out in various immune-related diseases.