Many complex terms and numerous abbreviations are used in the field of oncology. Many patients likely do not fully understand these terms, whether they hear them during their oncology visits or when reading through information that they find themselves. The purpose of this fact sheet is to explain some of the more commonly used terms in oncology. Other resources are available that provide a more comprehensive and searchable glossary, such as the National Cancer Institute Dictionary of Cancer Terms or the American Society of Clinical Oncology’s Cancer.Net Cancer Terms.1,2

Diagnosis and Disease Terms

There are 2 major types of cancers, those that are referred to as solid tumors and those that are considered blood cancers. Solid tumors are any cancers that begin within a solid tissue or organ, whereas blood cancers originate with cells that are present in the blood, but do not form a solid mass. A tumor is essentially a group of abnormal, or atypical, cells that form a ball of tissue. Tumors can be cancerous or benign. Benign means that although the cells are abnormal, they are not truly considered cancerous, and there is no risk for it spreading beyond the location of the tumor. Benign tumors are rarely life-threatening.

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Many patients are familiar with the concept of hereditary cancers, when cancer runs in families and is seemingly “passed on” to family members. In these cases, specific mutations in genes that are associated with cancer are inherited and can (but not always) result in cancer. However, the majority of the time cancer is sporadic, meaning it develops without a clear link to inherited traits.

When cancer is diagnosed, it is staged, meaning it is categorized based on severity. When the cancer is staged several factors are typically considered, including the size of the tumor and whether or not it has spread beyond a primary site. Metastatic cancer is disease that has spread beyond the original tumor. Distant metastases include cancers where cancer cells are found in other organs than where the original tumor was found. For example, if the original cancer is lung cancer and a group of cancerous cells are found in the liver, it is considered to be a distant metastasis. Locally advanced cancers are those that have spread beyond the original tumor, but nearby, such as to the nearby lymph nodes or just beyond the border of the original tumor.