The genetic or microscopic appearance of a cancer cell enables a pathologist to determine whether a patient has breast cancer, skin cancer, or some other type of tumor.

This is because the cancer cell resembles the organ that has cancer – not in shape, but in the microscopic or genetic appearance of the cells. That is how pathologists – doctors who diagnose diseases – determine what type of cancer a patient has.

With this information, the treating oncologist is able to predict how the tumor will grow and progress, as well as how it will react to treatment, explains Robert J. Morgan, Jr., MD, FACP, a medical oncologist at City of Hope in Duarte, California.

When a person is diagnosed with cancer, the oncologist should explain the name of the cancerous tumor, where it is located, how it will grow, and the available treatment options so that the patient can make informed decisions about care and treatment.

Cancer tumors are initially broken down into solid tumors (organ tumors) and liquid tumors (blood cancers). This article explains the similarities and differences between these different types of tumors.

Both types of tumors are similar in that they are made of abnormal cells that grow uncontrollably. In general, the solid tumors form a mass or multiple masses, and the liquid tumors circulate around the body through the bloodstream.

Solid Tumors

Solid tumors refer to a solid mass of cancer cells that grow in organ systems and can occur anywhere in the body. “All of the solid systems in the body can have cancer,” says Paul F. Engstrom, MD, an oncologist at Fox Chase Cancer Center in Philadelphia.

Two types of solid tumors are seen in adults: epithelial tumors and sarcomas. Epithelial tumors, which can also be called carcinomas, account for 90% of the solid tumors people have, according to Engstrom, and they occur in the lining (epithelium) that is on the outside or inside of the organ.

For instance, the digestive system, which starts in the mouth and ends at the anus, is lined all the way down with an epithelium. An epithelial tumor can occur anywhere along that lining, so a person could have a mouth cancer, throat cancer, esophageal cancer, stomach cancer, bowel cancer, or anal cancer.

Sarcomas are also called “connective tissue tumors” because they occur in the tissue that keeps the organs together. Connective tissues are the muscles, tendons, fat, nerves and other tissues that connect, support or surround structures and organs in the body. Sarcomas are usually named for the type of tissue where they first occur, according to Morgan. For instance, bone tumors are called osteosarcomas (osteo means bone, sarcoma is the connective tissue tumor).

Tumors of the brain are observed in both children and adults. Children are also at risk for congenital tumors of the adrenal gland (neuroblastoma), kidney (Wilms tumor), muscle (rhabdomyosarcoma), and retina (retinoblastoma).

Liquid Tumors

Liquid tumors occur in the blood, bone marrow, and lymph nodes. They include leukemia, lymphoma, and myeloma. About 61,000 people are diagnosed with blood cancers each year, and both adults and children can develop a blood cancer. Depending on the type of cancer a person has, the outcomes of blood cancers vary.

Leukemia is cancer of the bone marrow and blood. When the cancer causes an abnormal increase of the type of white blood cells called lymphocytes, the cancer is called lymphocytic leukemia. When the cancer causes an increase in the type of white blood cells called granulocytes, the cancer is called myeloid leukemia.

Leukemias can be either acute, which progress rapidly, or chronic, which progress more slowly.

“The acute leukemias are very treatable with chemotherapy and/or bone marrow transplantation,” says Laurence A. Boxer, MD, a pediatric hematologist-oncologist at the University of Michigan Comprehensive Cancer Center. “Chronic myeloid leukemia is treatable now with targeted therapies that inhibit the growth of the leukemia and have minimal affects on the rest of the cells of the body.”

The cause of leukemia is often unknown, but some cases have been linked to chronic exposure to benzene, an industrial chemical, or exposure to large doses of radiation. Benzene in cigarettes can increase one’s risk of leukemia of the myeloid cells.

Lymphoma is a blood cancer that starts in the immune system, affecting the tissue in the lymph nodes, spleen, liver, bone marrow, and other sites. Lymphomas start out as liquid tumors, but can also form solid tumors.

More than 8,000 people each year are diagnosed with Hodgkin lymphoma. The disease is more likely to occur among people aged 15 to 35 and adults older than 55. Hodgkin lymphoma usually spreads to other lymph nodes, but the spread is organized, moving from one lymph node to another in a systematic fashion.

Hodgkin lymphoma is a highly treatable cancer, and many people diagnosed with this disease can now be cured or the disease can be controlled for many years.

More than 60,000 people each year are diagnosed with non-Hodgkin’s lymphoma (NHL), and the disease can occur at any age. NHLs begin when the B cells or T cells in the immune system begin to grow abnormally. NHL also starts in the immune system but spreads randomly through the lymph nodes. There are several types of NHL, and they are characterized as fast-growing (aggressive) and slow-growing (indolent) forms.

The outcome of NHL depends on whether the lymphoma is aggressive or indolent, the stage of the lymphoma, the patient’s age, and whether other health problems are present.  

The cause of lymphoma is unknown, but some researchers think that some viruses, such as Epstein-Barr virus, may contribute to some cases. In addition, people with a weakened immune system have an increased risk, as do those with a sibling that has the disease.

Myeloma, or cancer of the plasma cells (a type of white blood cell), also begins in the immune system. Rapid cell growth forms a tumor in the bone marrow, which is the spongy tissue in the center of bone that makes platelets and red and white blood cells in the bone marrow.

No one knows what causes multiple myeloma, but age appears to be the most significant risk factor for developing the disease. Race and gender also appear to play a role. African-American men aged 67 and older are at the greatest risk of developing the disease.                                   

The goal in treating blood cancer is to achieve remission. Since a blood cancer can reappear, people with a blood cancer even in remission still need to see their doctors regularly.                               

There do not appear to be any lifestyle steps that people can take to avoid blood cancers, but anyone with cancer benefits from living a healthy lifestyle. Follow your doctor’s treatment recommendations. Stop smoking, reduce or stop drinking alcohol, eat a good diet, get plenty of rest, exercise daily, and take steps to alleviate life’s stressors.

Although more new cases of leukemia, lymphoma, and myeloma are diagnosed today than ever before, deaths from these cancers have decreased because many are detected earlier, and better treatments are available.