Cancer Diagnosis Differences Between a Malignant and Benign Tumor By Lisa Fayed Lisa Fayed is a freelance medical writer, cancer educator and patient advocate. Learn about our editorial process Lisa Fayed Medically reviewed by Medically reviewed by Doru Paul, MD on November 04, 2019 Doru Paul, MD, is board-certified in internal medicine, medical oncology, and hematology. Learn about our Medical Review Board Doru Paul, MD Updated on January 27, 2020 Print Table of Contents View All What Is a Tumor? Benign Tumors Malignant Tumors Differences Can Benign Turn Malignant? What Your Diagnosis Means If you have been diagnosed with a tumor, the first step your doctor will take is to find out whether it is malignant or benign, as this will affect your treatment plan. In short, the meaning of malignant is cancerous and the meaning of benign is non-cancerous. Learn more about how either diagnosis affects your health. Verywell / Joshua Seong What Is a Tumor? A tumor is an abnormal lump or growth of cells. When the cells in the tumor are normal, it is benign. Something just went wrong, and they overgrew and produced a lump. When the cells are abnormal and can grow uncontrollably, they are cancerous cells, and the tumor is malignant. To determine whether a tumor is benign or cancerous, a doctor can take a sample of the cells with a biopsy procedure. Then the biopsy is analyzed under a microscope by a pathologist, a doctor specializing in laboratory science. Benign Tumors: Noncancerous If the cells are not cancerous, the tumor is benign. It won't invade nearby tissues or spread to other areas of the body (metastasize). A benign tumor is less worrisome unless it is pressing on nearby tissues, nerves, or blood vessels and causing damage. Fibroids in the uterus or lipomas are examples of benign tumors. Benign tumors may need to be removed by surgery. They can grow very large, sometimes weighing pounds. They can be dangerous, such as when they occur in the brain and crowd the normal structures in the enclosed space of the skull. They can press on vital organs or block channels. Some types of benign tumors such as intestinal polyps are considered precancerous and are removed to prevent them becoming malignant. Benign tumors usually don't recur once removed, but if they do it is usually in the same place. Malignant Tumors: Cancerous Malignant means that the tumor is made of cancer cells, and it can invade nearby tissues. Some cancer cells can move into the bloodstream or lymph nodes, where they can spread to other tissues within the body—this is called metastasis. Cancer can occur anywhere in the body including the breast, intestines, lungs, reproductive organs, blood, and skin. For example, breast cancer begins in the breast tissue and may spread to lymph nodes in the armpit if it's not caught early enough and treated. Once breast cancer has spread to the lymph nodes, the cancer cells can travel to other areas of the body, like the liver or bones.The breast cancer cells can then form tumors in those locations. A biopsy of these tumors might show characteristics of the original breast cancer tumor. Differences Between Benign and Malignant Tumors Although there are exceptions—for example, although most malignant tumors grow rapidly and most benign ones do not, there are examples of both slow-growing cancerous tumors and non-cancerous ones that grow quickly—the main differences between the two types of tumors are clear and consistent. Here's a snapshot of the main ones: Characteristics of Benign Tumors Cells tend not to spread Most grow slowly Do not invade nearby tissue Do not metastasize (spread) to other parts of the body Tend to have clear boundaries Under a pathologist's microscope, shape, chromosomes, and DNA of cells appear normal Do not secrete hormones or other substances (an exception: pheochromocytomas of the adrenal gland) May not require treatment if not health-threatening Unlikely to recur if removed or require further treatment such as radiation or chemotherapy Characteristics of Malignant Tumors Cells can spread Usually grow fairly rapidly Often invade basal membrane that surrounds nearby healthy tissue Can spread via bloodstream or lymphatic system, or by sending "fingers" into nearby tissue May recur after removal, sometimes in areas other the original site Cells have abnormal chromosomes and DNA characterized by large, dark nuclei; may have abnormal shape Can secrete substances that cause fatigue and weight loss (paraneoplastic syndrome) May require aggressive treatment, including surgery, radiation, chemotherapy, and immunotherapy medications Can a Benign Tumor Turn Malignant? Some types of benign tumors only very rarely transform into malignant tumors. But some types, such as adenomatous polyps (adenomas) in the colon have a greater risk of transforming into cancer. That is why polyps, which are benign, are removed during colonoscopy. Removing them is one way of preventing colon cancer. It's not always clear-cut whether a tumor is benign or malignant, and your doctor may use several different factors to diagnose it as one or the other. You may end up with an uncertain diagnosis. Also, it is possible that a biopsy finds precancerous cells or misses the area where the cancerous cells are more prevalent. In these cases, what was thought to be benign might turn out to be malignant as it further grows and develops. What Your Tumor Diagnosis Means If you have been diagnosed with a malignant tumor, your oncologist (cancer doctor) will devise a treatment plan with you based on the stage of cancer. Early-stage cancers haven't spread much, if at all, whereas later-stage cancers have spread to more areas of the body. Determining the stage of cancer may require biopsies, surgery, and/or imaging tests. Once the cancer stage is determined, you can proceed with therapy. If you have been diagnosed with a benign tumor, your doctor will provide reassurance that you do not have cancer. Depending on the type of benign tumor, your doctor may recommend observation or removal for cosmetic or health purposes (for instance, the tumor may be compromising an important organ in your body). A Word From Verywell Being diagnosed with a tumor can be an anxiety-ridden experience. Be sure to discuss your concerns with your doctor and ask whether there are any support groups that you can join. And remember, the earlier that you or your doctor detects a lump, the more likely the tumor is treatable. So if you notice something unusual on your body, don't wait to tell your doctor. How Are Cancer Cells Different Than Normal Cells? 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 Article 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. Wan Z, Yin T, Chen H, Li D. Surgical treatment of a retroperitoneal benign tumor surrounding important blood vessels by fractionated resection: A case report and review of the literature. Oncol Lett. 2016;11(5):3259-3264. doi:10.3892/ol.2016.4395 Institute for Quality and Efficiency in Health Care (IQWiG). How do cancer cells grow and spread? 2016. Coleman HG, Loughrey MB, Murray LJ, et al. Colorectal Cancer Risk Following Adenoma Removal: A Large Prospective Population-Based Cohort Study. Cancer Epidemiol Biomarkers Prev. 2015;24(9):1373-80. doi:10.1158/1055-9965.EPI-15-0085 Additional Reading What are Tumors? Johns Hopkins Medicine. Benign Tumors. National Institute of Health. MedlinePlus. Updated 07/07/16. What is Cancer? National Cancer Institute. Updated 02/09/15. What is Cancer?: A Guide for Patients and Families. American Cancer Society. Updated December 2015. An, Y., Kim, S., and B. Kang. Differentiation of Malignant and Benign Breast Lesions: Added Value of the Qualitative Analysis of Breast Lesions on Diffusion-Weighted Imaging (DWI) Using Readout-Segmented Echo-Planar Imaging at 3.0 T. PLoS One. 2017. 12(3):e0174681.