A tumor is an abnormal mass of tissue that forms when cells divide more than they should or do not die as they should. These growths can develop almost anywhere in the body, varying in size from small nodules to larger masses. While the term “tumor” often brings to mind cancer, not all tumors are cancerous. Understanding how tumors are classified, particularly through a system known as grading, is an important step for patients and their families.
Defining Tumor Grades
Tumor grading evaluates how much cancer cells resemble normal cells and tissues under a microscope. This assessment helps predict a tumor’s likely behavior and how quickly it might grow or spread. Low-grade tumors are often described as “well-differentiated,” meaning their cells look and organize much like healthy cells in the tissue where they originated.
Grade 1 tumors, considered low-grade, have cells very similar to normal cells and tend to grow slowly. In contrast, high-grade tumors (Grade 3 or 4) consist of cells that appear very abnormal, are poorly differentiated, and typically grow and spread more rapidly. Pathologists also assess mitotic activity, the rate at which cells are dividing; low-grade tumors generally exhibit rare mitotic activity, indicating slower cell reproduction.
How Low-Grade Tumors Behave
Low-grade tumors generally exhibit less aggressive behavior compared to their high-grade counterparts. They are characterized by a slow growth rate, often over many years. This slower growth means they are less likely to invade surrounding tissues aggressively or spread to distant parts of the body, a process called metastasis. Despite their less aggressive nature, low-grade tumors are still considered malignant, meaning they are cancerous. They have the potential to grow continuously and can, over time, transform into higher-grade, more aggressive forms.
Identifying and Understanding the Outlook
Low-grade tumors are often discovered incidentally through imaging scans, such as MRI or CT, performed for other reasons. The definitive diagnosis and grading of a tumor require a biopsy, where tissue samples are removed and examined by a pathologist under a microscope. The outlook for individuals with low-grade tumors is generally more favorable compared to those with high-grade tumors. Their slower growth rate and reduced tendency to spread often lead to longer survival rates. While the outlook can vary based on the specific tumor type, its location, and individual patient factors, many low-grade tumors are associated with extended periods of stable disease, with some exceeding 15 years.
Management and Care
The management of low-grade tumors involves treatment strategies that are often less intensive than those for high-grade cancers. One approach for certain slow-growing low-grade tumors, particularly if they are not causing symptoms, is watchful waiting or active monitoring. This involves regular check-ups and imaging scans, such as MRI, to monitor the tumor’s size and characteristics over time, with intervention initiated if the tumor grows or symptoms develop. Surgical removal is a common primary treatment, especially if the tumor is in an accessible location and can be removed without causing significant neurological deficits; studies suggest that maximizing the extent of surgical resection can improve overall survival and delay progression. Depending on the tumor type, location, and individual circumstances, less intensive forms of radiation therapy or chemotherapy might also be considered, sometimes in combination with surgery.