Prophylaxis: Nausea, Infection, Clots and Bone Protection

What is it?

Prophylaxis is protection given to reduce a side effect or complication before it appears. In oncology it is most often discussed for nausea and vomiting, neutropenic fever, venous blood clots, reactivation of hepatitis B and bone events.

The protection is not prescribed as the same package for every patient. The vomiting risk of the drug, the fever risk of the regimen, performance status and accompanying diseases change the decision.

How does it work?

In regimens with a high risk of vomiting, ondansetron or granisetron (5-HT3 antagonists), aprepitant or fosaprepitant (NK1 antagonists) and dexamethasone are considered together on the day of treatment. Olanzapine is added in selected high-risk regimens. MASCC and ESMO separate this choice according to the risk group.

Filgrastim and pegfilgrastim aim to recover a falling neutrophil count more quickly. ASCO recommends primary protection in regimens with a febrile neutropenia risk of about 20 percent or more, and in intermediate risk a decision based on factors such as age and additional disease. An automatic growth factor is not required after every course.

In which cancers is it used?

Nausea prophylaxis accompanies chemotherapy or some ADC regimens and depends on the drug more than on the cancer type. Clot protection is discussed in hospitalised patients and in selected outpatients with a high Khorana score. ASCO does not recommend routine anticoagulant drugs for every outpatient with cancer. Drugs such as low-molecular-weight heparin, apixaban and rivaroxaban are considered only in a suitable person.

In those who are positive for hepatitis B surface antigen or core antibody, suppression with entecavir or tenofovir may be needed, especially before drugs that affect B cells such as rituximab. Screening is requested before systemic treatment starts. Which treatment is appropriate is discussed at the tumour board, with the relevant specialties taking part, by considering the type, stage and molecular features of the cancer and the person’s general condition together.

How is it given?

Nausea drugs are used with the first dose in the treatment unit and at home on a written time schedule. The growth-factor injection is taught so that it does not coincide with the day of chemotherapy, in the days after the course. For vaccination, inactivated flu, COVID-19 and pneumococcal vaccines are considered in many adult patients with cancer. Live vaccines are generally postponed during intensive treatment.

For bone protection, zoledronic acid can be given intravenously and denosumab subcutaneously at set intervals. They have a place in bone metastasis in breast cancer, prostate cancer and myeloma, or in selected early breast cancer. Before starting, a dental check and calcium and vitamin D are discussed.

During follow-up, blood tests, imaging and symptom review are read together. The dose or date may be changed according to side effects and organ function. The list of medicines used at home is updated at every visit. Sudden fever, shortness of breath, uncontrolled diarrhoea or bleeding should be reported the same day.

Possible side effects

Ondansetron can cause constipation, dexamethasone sleeplessness and high blood sugar, and olanzapine drowsiness. A growth factor can cause bone pain. Anticoagulant drugs increase the risk of bleeding. Zoledronic acid can cause a flu-like picture with the first dose, and denosumab and zoledronic acid, though rarely, carry a risk of osteonecrosis of the jaw. Antiviral drugs also have their own interactions.

Fever, black stools, one-sided swelling in the leg or a sore on the gum that does not close should be reported the same day. The protective drug does not replace the main treatment.