Patient Education

Introduction

Cancer specialists treating cancer with drugs will have to know how to manage nausea and vomiting associated with cancer chemotherapy. Nausea refers to the unpleasant feeling of wanting to vomit. For some people, it can worse than vomiting. Some patients may describe it as an upset stomach, sea or motion sickness, bloated feeling, heartburn or sick to the stomach. Other patients may retch or puke without much output as they have not been eating.

Chemotherapy drugs are classified according to the frequency of vomiting as high (>90%) , moderate (30-90%), low (10-30%) or minimal (<10%) risk. However, there are other factors like the dose of the medication used, and other patient factors that affect the chance of vomiting as well.

Cisplatin, for example, is classified as a highly emetogenic drug. It is a common chemotherapy drug used in the treatment of cancers such as non-small cell lung cancer, ovarian cancer, testicular germ cell cancer, gastric (stomach) cancer, oesophageal cancer, cervix cancer, bone cancer, head & neck cancers, bladder cancer and other cancers. At the appropriate dose, it needs proper premedication to avoid nausea and vomiting to be a problem that might restrict its use.

Six things to know…

1. Classification

Not all nausea and vomiting are the same. The early onset, delayed onset and anticipatory vomiting have different underlying mechanisms and drugs that work for them.

Classification

• Acute (0-24 hr after chemotherapy)

• Delayed (24-120 hr after chemotherapy)

• Anticipatory (prior to chemotherapy)

2. Mechanism of nausea and vomiting

Central mechanism

The chemoreceptor trigger zone (CTZ) is the part of the brain involved in sensing drugs, medications and hormones. As a result of its connection to the vomiting centre, drugs acting on chemical mediators (neurotransmitters) here would trigger off the sensation of nausea or vomiting. The implicated neurotransmitters include dopamine, histamine (H1 receptor), substance P (NK-1 receptor), acetylcholine and serotonin (5 HT3 receptor).

Peripheral mechanism

Chemotherapy agents can cause irritation to the stomach or gastrointestinal lining with resulting release of neurotransmitters. These might then send signals to the vomiting centre in the brain. Patients may have heartburn or queasy feeling.

Combined mechanism

Some drugs work via both central and peripheral systems to cause nausea and vomiting.

3. In managing chemotherapy related side effects of nausea and vomiting, prevention is better than treatment

The adage “prevention is better than cure”, holds true especially for post-chemotherapy vomiting and nausea. Many patients would say that the nauseous feeling can begin just thinking about the next chemotherapy treatment. This is termed anticipatory vomiting. At OncoCare Cancer Centre, Singapore, our doctors and nurses are aware of this and preventing this in the first place depending on the chemotherapy that is planned for is important. We work with the patients to manage this crucial aspect of chemotherapy treatment.

4. Antiemetic drug or medications

These medications are called anti-nausea drugs or anti-emetics (drugs for vomiting).

Some common medications used are listed below:

5-HT 3 receptor antagonist

• Ondansetron (Zofran)

• Granisetron (Kytril)

• Palonosetron (Aloxi)

Corticosteroids

• Dexamethasone

NK1 receptor antagonist

• Aprepitant (Emend)

Dopamine receptor antagonist

• Prochlorperazine

• Metoclopramide

Benzodiazepines

• Lorazepam (Ativan) (this is sometimes given under the tongue for patients so they do not vomit it out)

A combination of drugs may be used to prevent acute and delayed vomiting.

Drugs may also be given to reduce acid in the stomach which may include famotidine, omeprazole or similar class of medications.

5. Non- drug management of nausea and vomiting

General measures

• Drink plenty of fluids. If a patients cannot take other food, having soups, or juices may provide some of the calorie needs so the patient is not too tired.

• Eat small amounts of food throughout the day.

• Avoid heavy, high fat and greasy meals just before chemotherapy.

• Do not get too hungry before you eat.

• Certain food that one might normally like, may become unbearable because of altered taste, so be aware and not be too stuffed by one’s favourite food.

• Ice chips or ice cream may be a helpful way of getting some fluids

6. Other causes of nausea and vomiting in cancer patients

Just because a cancer patient has chemotherapy does not mean that all the cases of nausea and vomiting are related to the chemotherapy. There have been many situations whereby cancer-related complications is the cause of the vomiting. These situations can arise from

• gastric or intestinal obstruction (such as from colorectal cancer, gastric cancer, pancreatic cancer),

• brain metastasis (which can be common in lung cancer, breast cancer and melanomas)  with increase in intracranial pressure (pressure in the brain system),

• septicaemia (blood infection), urine tract infections, and

• other non-chemotherapy medications or other causes of vomiting.

The alert oncologist or cancer specialist doctor should be aware and evaluate for these situations.

7. The ultimate solution – a saline drip

In the event that patients are really tired and not able to take orally because of chemotherapy or other medications given to treat cancer, an intravenous drip of saline which can replenish lost fluids, salt and sugar is available.  In Singapore, patients should not have too much difficulty getting access to their oncologist to have a drip. At our private oncology clinic, OncoCare Cancer Centre, Singapore, this can be done as an outpatient setting. Once an intravenous line is established, the fear of drinking and throwing up is resolved. Some of the medications can be given as an intravenous injection so patients do not need to worry about taking the anti-emetic and throwing it up. Having the ultimate “solution” available gives the patient peace of mind to have needed chemotherapy for their cancer.

“Expert knowledge means better care for cancer”

Written by:

Dr Peter Ang
MBBS (Singapore)
MMed (Int Med)
MRCP (UK)
FAMS (Medical Oncology)