The immune system protects the body against infections caused by bacteria, viruses, fungi and other microorganisms. Some types of cancer and certain cancer treatments can weaken the body's natural defences and increase the risk of infection.

This may happen because:

• Some cancers, particularly leukaemias and lymphomas, can affect the bone marrow and interfere with the normal production of white blood cells, which help fight infections.
• Chemotherapy and some forms of radiotherapy can temporarily reduce the number of white blood cells in the bloodstream (neutropenia), increasing the risk of infection.
• Surgery, central venous catheters, PICC lines and other medical devices can allow microorganisms to enter the body if they are not properly cared for.

If your immune system is weakened, the following measures may help reduce your risk of infection:

• Avoid close contact with people who have an infection, a cold, influenza or any other contagious illness.
• Wash your hands frequently, especially before eating, after using the toilet and when returning home. Family members and carers should also maintain good hand hygiene.
• Maintain good personal hygiene, including daily skin care.
• Maintain good oral hygiene and regularly check for mouth ulcers, white patches or signs of infection.
• Follow food safety recommendations by eating thoroughly cooked foods, storing food correctly and avoiding spoiled or unsafe food products.
• Care for your central venous catheter or PICC line according to the instructions provided by your healthcare team.
• Always consult your healthcare team before receiving any vaccination. Some vaccines may not be appropriate during certain cancer treatments.
• Avoid crowded places or environments with a higher risk of exposure to infections when specifically advised by your healthcare team.