Acute Granulocytic Leukemia.

Acute granulocytic leukemia cancer of the white cells that engulf bacteria closely resembles several other leukemias in behavior, treatment, and prognosis. Because these related disorders acute my-elomonocytic leukemia (leukemia of monocytes) and erythroleukemia (leukemia of red cells)—each constitute only about one percent of all blood cancers, they and acute granulocytic leukemia are often conveniently grouped together under the term "acute nonlymphocytic leukemia."

The prominent symptoms of acute granulocytic leukemia (and all the other acute leukemias of blood cells that are not derived from lymphocytes) are pallor, weakness, fever, and fatigue. The typical patient is thirty to sixty years old, the frequency of the disease increasing with age. The natural course of untreated acute granulocytic leukemia leads to an average survival of only two to five months. Chemotherapy has lengthened survival to as long as five years, but the disease is still serious and basically incurable.

Treatment regimens for acute granulocytic leukemia and the other nonlymphocytic leukemias are not the same in all cancer centers, and a wide variety of schedules is used for the induction and maintenance of remission. Complete remission can be achieved in about 75 percent of patients, up from only 33 percent some years ago, but it lasts only for twelve to fifteen months.

Several complications can occur in the course of these leukemias. Leukostasis, the clumping of immature white cells, is a dangerous condition that occurs when the white blood cell count is 300,000 or higher, about thirty to fifty times normal. Since it can cause heart attacks and strokes by blocking the arteries, it is treated by removing large numbers of white cells from the patient's blood and increasing the intensity of the chemotherapy. Masses of white cells, called chloromas or myeloblastomas, can form, resulting in nodules beneath the skin, obstruction of the intestines, and other mechanical problems. Monocytic leukemia, one of the nonlymphatic cancers, can be diagnosed with almost complete certainty on the basis of its characteristic visible invasion and infiltration of the cheeks and gums. Infiltration of the central nervous system, which occurs in about 50 percent of patients with acute lymphocytic leukemia, is rarely found in patients with this group of blood cancers, making specific treatment and prophylaxis for disease involving the brain and spinal column unnecessary.

Bone marrow transplantation has not been extensively tried in cases of acute nonlymphatic leukemia, in part because of the older age of the patients in this group.
Abnormalities of the chromosomes occur in over 50 percent of patients with acute granulocytic leukemia and related disorders. Evidence strongly suggests that each patient's individual chromosomal makeup has a strong direct bearing on prognosis. Patients found to have abnormal genes in their leukemic cells (not in their other normal cells) typically have a less favorable prognosis.

Erythroleukemia, while it appears to be a malignancy of red cells, is actually a malignancy of both white and red cell lines. This observation suggests that the origin of this cancer may lie in the stem cell, the common ancestor in the marrow of both white and red cell lines. The clinical picture of erythroleukemia resembles the general description of the leukemias as a group. The disorder is difficult to treat satisfactorily; most patients have severe anemia and require repeated transfusions. Although complete remission is obtainable in 40 to 50 percent of patients, the average survival from the time of diagnosis is six to eight months.