Cancer Colon Cancer The Role Eosinophils Play in Cancer By Suzanne Dixon, MPH, RD Suzanne Dixon, MPH, RD LinkedIn Twitter Suzanne Dixon, MPH, MS, RDN, is an award-winning registered dietitian and epidemiologist, as well as an expert in cancer prevention and management. Learn about our editorial process Updated on July 01, 2020 Medically reviewed Verywell Health articles are reviewed by board-certified physicians and healthcare professionals. These medical reviewers confirm the content is thorough and accurate, reflecting the latest evidence-based research. Content is reviewed before publication and upon substantial updates. Learn more. by Douglas A. Nelson, MD Medically reviewed by Douglas A. Nelson, MD LinkedIn Douglas A. Nelson, MD, is a board-certified oncologist and hematologist who previously served for 13 years as a physician in the US Air Force. Learn about our Medical Expert Board Print Eosinophils are a type of white blood cell produced in the bone marrow that makes up about 5 percent of the total number of white blood cells. Eosinophils can circulate in the blood and also are found outside blood vessels in other organs in the body. The gastrointestinal (GI) tract typically has the highest number of eosinophils relative to other organs. FatCamera / Getty Images The Function of Eosinophils Eosinophils protect the body by killing bacteria and parasites, but can cause problems when they react incorrectly and cause allergies and other inflammatory reactions in the body. For example, food allergies can cause too many eosinophils to gather in the digestive tract, which may lead to symptoms such as diarrhea and damage to the cells lining the GI tract. Eosinophils are part of the innate immune system, which means that they can "non-specifically" destroy any invaders they encounter in the body, such as bacteria and parasites. Eosinophils do not have to recognize the invader specifically, but instead simply recognize the invader as something that is foreign to the body and should not be present. When There Are Too Many Eosinophils When a large number of eosinophils are dispatched to a certain site in the body, or when the bone marrow produces too many eosinophils, a condition known as eosinophilia exists. Eosinophilia can result from a variety of conditions, diseases, and factors, including: Parasitic and fungal diseases Allergies Adrenal conditions Skin disorders Toxins Autoimmune diseases Endocrine disorders In addition, eosinophilia can develop in response to certain cancers, including: Lymphoma (Hodgkin's and non-Hodgkin's lymphoma) Leukemia (chronic myeloid leukemia, adult T-cell leukemia/lymphoma, eosinophilic leukemia) Colorectal cancer Lung cancer What to Know If You Have Eosinophilia Eosinophils and Colorectal Cancer The number of eosinophils in the blood can rise during a normal response to allergic reactions, fungal and parasitic infections, medications, and some types of cancer. A study published in the journal Modern Pathology in 2014 looked at how eosinophils might predict outcomes for patients with colorectal cancer. Although staging of colorectal cancer typically is based on information about the tumor itself, lymph node involvement, and the presence of metastases (cancer spread to other sites), often two patients with the same staging will have dramatically different outcomes. The study's authors examined whether eosinophil levels in or around a colorectal tumor helped predict outcome. They concluded that higher numbers of eosinophils around the primary colorectal tumor were associated with an improved patient outcome and, as a result, that eosinophils should be routinely counted during tumor examination. Was this page helpful? Thanks for your feedback! Limiting processed foods and red meats can help ward off cancer risk. These recipes focus on antioxidant-rich foods to better protect you and your loved ones. Sign up and get your guide! Sign Up You're in! Thank you, {{form.email}}, for signing up. There was an error. Please try again. What are your concerns? Other Inaccurate Hard to Understand Submit 9 Sources Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy. Blumenreich MS. The White Blood Cell and Differential Count. In: Walker HK, Hall WD, Hurst JW, editors. Clinical Methods: The History, Physical, and Laboratory Examinations. 3rd edition. Boston: Butterworths; 1990. Chapter 153. Available from: https://www.ncbi.nlm.nih.gov/books/NBK261/ Mehta P, Furuta GT. Eosinophils in Gastrointestinal Disorders: Eosinophilic Gastrointestinal Diseases, Celiac Disease, Inflammatory Bowel Diseases, and Parasitic Infections. Immunol Allergy Clin North Am. 2015;35(3):413–437. doi:10.1016/j.iac.2015.04.003 Ramirez GA, Yacoub MR, Ripa M, et al. Eosinophils from Physiology to Disease: A Comprehensive Review. Biomed Res Int. 2018;2018:9095275. Published 2018 Jan 28. doi:10.1155/2018/9095275 Shamri R, Xenakis JJ, Spencer LA. Eosinophils in innate immunity: an evolving story. Cell Tissue Res. 2011;343(1):57–83. doi:10.1007/s00441-010-1049-6 Kovalszki A, Weller PF. Eosinophilia. Prim Care. 2016;43(4):607–617. doi:10.1016/j.pop.2016.07.010 Long H, Zhang G, Wang L, Lu Q. Eosinophilic Skin Diseases: A Comprehensive Review. Clin Rev Allergy Immunol. 2016;50(2):189–213. doi:10.1007/s12016-015-8485-8 Beishuizen A, Vermes I, Hylkema BS, Haanen C. Relative eosinophilia and functional adrenal insufficiency in critically ill patients. Lancet. 1999;353(9165):1675–1676. doi:10.1016/s0140-6736(99)01346-x Prizment AE, Vierkant RA, Smyrk TC, et al. Tumor eosinophil infiltration and improved survival of colorectal cancer patients: Iowa Women's Health Study. Mod Pathol. 2016;29(5):516–527. doi:10.1038/modpathol.2016.42 Harbaum L, Pollheimer MJ, Kornprat P, Lindtner RA, Bokemeyer C, Langner C. Peritumoral eosinophils predict recurrence in colorectal cancer. Mod Pathol. 2015;28(3):403-13. Additional Reading Modern Pathology. "Peritumoral eosinophils predict recurrence in colorectal cancer." Journal of Clinical Oncology. 29:2011. "Peripheral blood eosinophil counts and risk of colorectal cancer mortality in a large general population-based cohort study."