Chemotherapy (also known as chemo) is a treatment method that uses drugs to treat cancers, either by killing the cancer cells or by stopping them from dividing. Chemo medications may be administered as monotherapy (i.e., a single agent), but very often multiple agents are combined to ensure therapeutic efficacy. Chemo may be given by different routes of administration, such as, by mouth, via injection, or under the skin, etc., depending on the types and stages of cancer. Although adverse effects may vary based on the selection of drugs, common side effects of chemo include the following. 

Chemotherapy-induced Nausea and Vomiting (CINV)

Nausea and vomiting occur in 30-90 per cent of patients receiving chemo, and 40-60 per cent of patients continue to experience symptoms of nausea and vomiting despite using preventative medication.

• Risk factors of CINV include high-emetogenic chemo (i.e., medications with a high risk of causing nausea and vomiting in most patients), female gender, patients with a history of motion sickness, pregnancy-related nausea and vomiting, and poor CINV control of the previous chemo cycle.

• Types of CINV: Each type would require different prevention and treatment regimens.

– Acute CINV occurs within the first 24 hours of chemo.

– Delayed CINV occurs more than 24 hours after chemo for up to one week.

– Anticipatory CINV occurs prior to chemo as a psychological response.

– Breakthrough CINV occurs despite preventative treatment.

Mucositis is another common side effect that refers to the inflammation of the oral mucosa (i.e., the soft tissue membrane that lines the structures in the mouth) caused by chemotherapy.

• Prevention of CINV is an important component in patient care, as CINV has a significant physical and emotional impact on cancer patients, such as, decreasing the patient’s quality of life and their willingness to continue chemo. Prevention would generally involve the following drug categories and they can be used alone or in combination, depending on the emetogenicity (the potential of causing nausea and vomiting) of the specific chemo that is being administered.

– Serotonin 5-hydroxytryptamine-3 (5-HT3) receptor antagonists (e.g., ondansetron, palonosetron)

– Neurokinin-1 (NK-1) receptor antagonists (e.g., aprepitant, fosaprepitant)

– Glucocorticoids (e.g., dexamethasone)

In terms of non-pharmacological options to manage CINV, it is recommended for patients to eat smaller meals, stay well hydrated, avoid foods with heavy smells and other triggers.

Febrile Neutropenia (FN)

Febrile neutropenia (FN) is a serious condition often associated with chemo. It occurs when a patient develops a fever while their blood neutrophil (i.e., a type of white blood cells) count is critically low, which can potentially lead to life-threatening infections. Cancer patients undergoing chemo who develop a fever should be promptly assessed. It is important for patients to perform regular temperature checks and seek immediate medical attention if their temperature reaches or exceeds 38°C for one hour or 38.3°C under any circumstances.

• Risk factors of FN include patients who are undergoing dose-dense chemotherapy (i.e., chemo drugs are given with less time between treatments than in a standard chemo treatment plan), receiving bone marrow radiation, or having previously experienced FN.

• Prevention of FN with granulocyte-colony stimulating factor (G-CSF) should be considered when chemo is initiated. There are two types of G-CSF, short-acting and long-acting (e.g., filgrastim and pegfilgrastim), both of which are equally effective and administered via subcutaneous injection. The choice of G-CSF agent will depend on the type and frequency of the chemo cycle. Common side effects include bone and musculoskeletal pain, nausea, fatigue, and fever. Since G-CSF is self-administered at home, it is important for healthcare providers to provide patients with detailed counseling on storage, injection techniques, and proper disposal of sharps. At the same time, patients should always consider the 5 Questions to Ask About Your Medications (https://www.ismp-canada.org/medrec/5questions.htm) during a clinical encounter with their healthcare providers, which will help them better informed of their medications. 

Mucositis

Mucositis is another common side effect that refers to the inflammation of the oral mucosa (i.e., the soft tissue membrane that lines the structures in the mouth) caused by chemotherapy. It typically presents as erythema (i.e., redness) or ulcerations of the oral mucosa, resulting in oral pain that makes it difficult for cancer patients to open their mouths, eat, and drink, which may significantly impact their quality of life.

• Prevention of mucositis: Oral Care

Prior to the initiation of chemotherapy, inform patients the importance of oral care to prevent mouth complications. Patients should brush their teeth using a soft-bristled toothbrush to prevent irritation and gum bleeding. They should also avoid using alcohol-containing mouthwash. Instead, they can rinse their mouth with a salt and/or baking soda solution several times after brushing, eating, before bedtime, and as needed. 

• Management of mucositis: Pain Relief

Benzydamine, lidocaine 2 per cent viscous, and “Pink Lady” or Magic mouthwash are first-line options to be applied as needed. If severe pain persists despite topical treatments, acetaminophen or occasionally opioids can be used. However, it is important to note that acetaminophen may mask febrile neutropenia (FN), therefore, patients should check their body temperature before taking the medication.

The above highlights some of the key considerations on safe medication use when managing three common side effects of chemotherapy. Readers are encouraged to consult further resources if they are interested to learn more about chemotherapy as well as prevention and management of chemo induced side effects. Selected resources are as follows:

• Canadian Cancer Society: Treatments – Side Effects – https://cancer.ca/en/treatments/side-effects

• Cancer Care Ontario: Symptoms & Side Effects of Chemotherapy –  https://www.cancercareontario.ca/en/cancer-treatments/chemotherapy/symptoms-side-effects

• BC Cancer: Clinical Resources – https://www.bcancer.bc.ca/health-professionals/clinical-resources 

By Zhiting (Tina) Zhou, Xinyue (Iris) Zhao, and Certina Ho

Zhiting (Tina) Zhou and Xinyue (Iris) Zhao are 2024 PharmD graduates at the Leslie Dan Faculty of Pharmacy, University of Toronto; and Certina Ho is an Assistant Professor at the Department of Psychiatry and Leslie Dan Faculty of Pharmacy, University of Toronto.