infection-prevention

The viruses behind cold sores and shingles stay in the body for life and can flare when cancer treatment weakens the immune system. People having intensive leukaemia treatment, a stem cell transplant, or myeloma drugs such as bortezomib are usually given an antiviral tablet, aciclovir or valaciclovir, to prevent this. Most people having ordinary chemotherapy for a solid tumour do not need it.

Hepatitis B can sleep in the liver for years and wake up when cancer treatment weakens the immune system, sometimes damaging the liver badly. A blood test before treatment finds people at risk. Those who have it, or have had it and get high-risk treatment such as rituximab or a stem cell transplant, take an antiviral tablet during and for at least a year after treatment, or are checked closely.

Pneumocystis is a fungus that can cause a dangerous pneumonia in people whose immune system is weakened by some cancer treatments, steroids or a stem cell transplant. An inexpensive antibiotic, co-trimoxazole, taken a few times a week or daily, prevents it very well. People who cannot take it have other options: atovaquone, dapsone or an inhaled medicine once a month.

Steroids for an immunotherapy side effect are reduced slowly, usually over at least 4 to 6 weeks, because stopping too fast can bring it back. A month or more of higher-dose steroids weakens defences against Pneumocystis pneumonia, so a preventive antibiotic (usually co-trimoxazole) is often given. Your body's own steroid production may need checking before the last tablets stop.

Before cancer treatment, the team should check which vaccines a person has had and bring them up to date, ideally two to four weeks before. Non-live vaccines such as the flu jab can still be given during treatment. Live vaccines, such as MMR, chickenpox and the nasal flu spray for the patient, must be avoided during treatment and for months after. Family vaccines protect the patient too.