What causes anaemia in cancer?

Anaemia means the blood has too little haemoglobin or too few red blood cells to carry oxygen efficiently. Cancer-related inflammation can alter how the body uses iron and can slow red-cell production. A tumour or treatment may cause bleeding, while poor appetite, digestive problems or other illness can reduce iron, vitamin B12 or folate. Cancers involving the bone marrow can directly interfere with blood-cell production. Chemotherapy can also suppress marrow activity. More than one factor may be present, so a low haemoglobin result needs clinical interpretation.

Tell your oncology team about tiredness, dizziness, breathlessness on exertion, paleness or a racing heartbeat. They may review a full blood count, iron and vitamin results, bleeding symptoms, kidney function and current treatment. Management depends on the cause and may include treating bleeding or deficiency, adjusting cancer treatment, or supportive treatment recommended by the team. Do not take iron or other supplements unless testing supports them.

Seek urgent help for breathlessness at rest, chest pain, fainting, confusion, a fast or irregular heartbeat, or bleeding that does not stop. Contact your oncology team promptly if fatigue suddenly worsens, stools become black, or you notice blood in vomit, urine or stool.

What type of anaemia do I have? Could treatment, bleeding, inflammation or a nutrient problem be contributing? Which tests are needed? How should I manage activity while my haemoglobin is low?