Understanding the disease we’re working to treat.
Cancer is a group of diseases in which abnormal cells grow uncontrollably and can invade and destroy healthy body tissue. It can also spread to other parts of the body.
Cancer is the second-leading cause of death in the world. But survival rates are improving for many types of cancer, thanks to improvements in cancer screening, treatment, and prevention.
Signs and symptoms caused by cancer vary depending on what part of the body is affected. Some general signs and symptoms associated with, but not specific to, cancer include:
A solid body cancer refers to an abnormal mass of tissue, or tumor, that develops within a specific organ or tissue in the body. This growth originates from the uncontrolled division of cells, leading to a distinct lump or mass. Such tumors can arise in various locations — including the breast, lung, colon, or prostate — forming a localized disease.
Solid cancers are characterized by their formation of a distinct, organized mass of cells within an organ, such as the lungs, breast, or colon. The disease remains largely contained within this physical structure, even as it grows.
In contrast, liquid cancers — also known as hematologic cancers — involve blood-forming tissues or cells of the immune system. Conditions like leukemia, lymphoma, and myeloma do not form a single, solid mass. Instead, these cancers circulate within the blood, bone marrow, and lymphatic system, affecting cells distributed throughout the body.
Solid tumors are broadly categorized based on the type of cells from which they originate. One major classification is carcinomas, which develop from epithelial cells. These cells line organs, glands, and body surfaces, and carcinomas account for a significant majority of all cancer diagnoses. Common examples include breast, prostate, lung, and colorectal cancer. Specific epithelial cell types can further classify these tumors — such as adenocarcinoma from glandular epithelial cells.
Another primary classification is sarcomas, which originate from connective tissues — including bone, muscle, fat, cartilage, and blood vessels — that provide structure and support throughout the body. Sarcomas are less common than carcinomas but can develop in almost any part of the body. Examples include osteosarcoma, which forms in bone tissue, and liposarcoma, which develops from fat cells.
Solid tumors begin when normal cells undergo genetic mutations that disrupt their regulated growth cycle, leading to uncontrolled division. These accumulating abnormal cells form a mass, which gradually expands in size. The initial growth often relies on existing blood vessels for nutrients and oxygen.
As the tumor grows larger, it requires its own dedicated blood supply to sustain its rapid proliferation. This process, known as angiogenesis, involves the tumor signaling to nearby blood vessels to sprout new branches that grow into the tumor mass.
The tumor exists within a complex tumor microenvironment. This includes not only the cancer cells themselves but also surrounding blood vessels, immune cells, fibroblasts (connective tissue cells), and the extracellular matrix. The tumor actively manipulates these components — signaling them to support its growth, evade immune detection, and facilitate its survival.
General signs and symptoms adapted from MayoClinic.org. This page is for general educational purposes and is not medical advice.