Anemia — Low Red Blood Cell Count

Anemia occurs when circulating erythrocyte mass is insufficient to meet the physiological oxygen requirements of peripheral tissues. In oncology, it is typically defined by a reduction in blood haemoglobin concentrations below standard reference ranges (often under 12.0 g/dL in women and 13.0 g/dL in men, depending on local laboratory thresholds). It compromises oxygen transport, leading to cellular hypoxia.

The etiology of cancer-related anemia is multifactorial. It may stem from myelosuppressive chemotherapy or radiotherapy suppressing bone marrow hematopoiesis. Chronic disease-associated inflammation also plays a prominent role: inflammatory cytokines elevate circulating hepcidin levels, which traps iron within storage macrophages and restricts functional erythropoiesis. Other contributors include direct bone marrow infiltration by neoplastic cells, nutritional deficiencies, and microscopic or macroscopic hemorrhage.

Anemia is a leading cause of cancer-related fatigue, which significantly impacts everyday physical functioning, independence, and overall quality of life. Left untreated, severe anemia strains the heart and may necessitate treatment dose reductions, therapy delays, or emergency blood transfusions. Keeping red blood cell levels within a safe range ensures patients can tolerate and stay on track with their treatment schedules.

Anemia is routinely diagnosed and monitored using a complete blood count, which measures total haemoglobin, haematocrit, and red cell indices. Further evaluation involves checking iron parameters, such as serum ferritin and transferrin saturation, to detect functional or absolute iron deficiency. Reticulocyte counts assess bone marrow activity, while renal panel tests assess erythropoietin production alongside vitamin B12 and folate levels.

Anemia can occur in virtually any malignancy, but it is particularly prevalent in hematological cancers that arise in or invade the bone marrow, such as multiple myeloma, myelodysplastic syndromes, and leukemia. It is also common in gastrointestinal malignancies like colorectal or gastric cancers due to chronic occult blood loss, as well as advanced lung, breast, and ovarian cancers treated with platinum-based chemotherapies.

Management of anemia depends on severity, underlying cause, and patient symptoms. Mild cases are monitored closely, whereas iron deficiency is treated with oral or intravenous iron preparations. For significant or symptomatic anemia, packed red blood cell transfusions provide immediate relief. In selected situations, erythropoiesis-stimulating agents are administered under strict guidelines to encourage red blood cell generation while avoiding thrombotic risks.