Introduction to Chemotherapy-induced Nausea and Vomiting

What is chemotherapy-induced nausea and vomiting (CINV)?

Chemotherapy-induced nausea and vomiting (CINV) is a common, but avoidable, side effect of cancer therapy.^1,2

Nausea can be defined as an unpleasant, wave-like sensation experienced in the back of the throat and/or the epigastrium that may culminate in vomiting (emesis).³ Vomiting is the forceful expulsion of the contents of the stomach, duodenum, or jejunum through the oral cavity.³

Nausea and vomiting are two of the most feared cancer treatment-related side effects for cancer patients and their families.⁴

Types of chemotherapy-induced nausea and vomiting

A number of CINV types have been reported, according to time of onset, patient experience and relationship to antiemetic therapy.²

Acute onset CINV² - Occurs 0-24 hours following chemotherapy treatment and can be prevented by administering anti-emetics prior to chemotherapy.

Delayed onset CINV² - Occurs between 24 hours and 5 days after treatment and observed in up to 80% of patients. 

Anticipatory CINV² - Occurs prior to chemotherapy as a conditioned response to previous treatment and estimated to occur in 10-44% of patients.

Breakthrough CINV³ - Defined as an event that happens in spite of optimal preventive treatment.

Refractory CINV³ - CINV that recurs in subsequent cycles of therapy when all previous preventive and rescue treatments fail.

Delayed and anticipatory symptoms are more difficult to control than acute symptoms and require different management.⁵

People can vary in their susceptibility to drug-induced nausea and vomiting. Those affected more often include women, people under 50 years of age, people with anxiety and those with a known history of nausea and vomiting, e.g. motion sickness or morning sickness during pregnancy.^5,6 Susceptibility also increases with repeated exposure to the cytotoxic drug⁵ and patients with poor control of CINV during past chemotherapy cycles are likely to experience it in subsequent cycles.³

Emetogenic potential of chemotherapy

Chemotherapy regimens vary in the extent to which they cause nausea and vomiting.⁶ Chemotherapy agents are classified according to their risk of inducing vomiting (emesis):⁷

• HEC: Highly emetogenic chemotherapy (risk >90%)
• MEC: Moderate emetogenic chemotherapy (risk 30-90%)
• LEC: Low emetogenic chemotherapy (risk 10-30%)
• Minimal emetogenic chemotherapy (risk <10%)

More than 30% of patients treated with both highly emetogenic (HEC) and moderately emetogenic (MEC) chemotherapy agents experience nausea in both acute and delayed CINV.¹

Consequences of chemotherapy-induced nausea and vomiting

CINV may lead to:⁸

• Impaired quality of life.
• Electrolyte imbalances and/or dehydration.
• Anorexia.
• Extended hospitalisation.
• Increased medical costs.
• Increased burden on healthcare professionals.