Chemotherapy Side Effects

It is both impossible and pointless to list every known side effect of every chemotherapy agent currently being used today. There are simply too many—too many agents, and too many side effects. The interested reader should read the label indications given by their doctors, or they can find a rundown of any drug side effect by searching the specific drug at MedlinePlus¹, a site maintained by the US National Library of Medicine.

Side effects: Overview

We may not be able to offer an exhaustive list of chemotherapy side effects, but we can itemize some of the more common ones into two general categories²:

Common Issues

• - Loss of appetite (a serious side effect, since when considering prognosis, oncologists often look for weight changes)
• - Nausea and vomiting (common; see below)
• - Fatigue and weakness (often brought on by anemia due to the loss of red blood cells)
• - Mouth and throat sores (common; see below)

Physical Changes

• - Hair loss (often cited as the most traumatic side effect of chemotherapy, the Mayo Clinic offers a wonderful article on what to expect³)
• - Taste changes (favorite foods may taste badly, or water may taste metallic)
• - Neuropathy (nerve endings in the hands and feet may cause numbness or tingling)
• - Chemobrain (perceived changes in cognitive ability)

Keep in mind that not all chemotherapy agents cause side effects, and that not everyone chemotherapy patient will experience side effects.

Why chemotherapy causes side effects⁴

Understanding the causes behind the common side effects caused by chemotherapy may help bring some comfort to those experiencing them. In order to understand that, we first have to understand the principles behind modern chemotherapy.

A living cell endures a multi- stage process in order to divide from one cell into two, a process called mitosis. At any stage along the way, the cell is vulnerable to making a catastrophic error. Chemotherapy drugs are designed to act upon one or more of those stages. For instance, one class of drugs are known as antimetabolites. These drugs are active when the cell cycle is in the S phase, meaning it has begun to synthesize DNA so that each new cell will have a full complement of genetic material. Antimetabolites prevent the cell from using chemicals necessary for DNA metabolism, thereby halting cell division and inducing cell death.

Since cancerous cells tend to divide at a more frequent clip than most healthy cells, they are more vulnerable to the various mechanisms in chemotherapy drugs. However, these drugs can't decipher between a healthy cell and a cancerous cell, so they kill cells indiscriminately. While cancerous cells divide more often than most cells, some cells in the body also divide at a rapid clip, and these cells, though healthy, are as vulnerable to chemotherapy as cancer cells.

In short, if the cells divide quickly, chemotherapy is more effective against them. Unfortunately, the cells in our hair follicles, in our mouths, throat, and throughout the entire digestive system, and the cells in the reproductive organs all divide quickly. Chemotherapy often kills these cells, and this leads to the side effects we're so familiar with, such as hair loss, and eating, appetite and digestive problems.

What can be done about these side effects

Chemotherapy-induced Nausea and Vomiting (CINV) is extremely common; in fact chemotherapy agents are classified by their emetic (vomit-inducing) risk, a classification that begins with the least emetogenic (level 1, almost nonemetogenic) up to the most (level 5, 90% chance of inducing emesis). While a patient should always tell their nurse or oncologist about CINV, in general, the best anti-emetic medicine is prevention—taking efforts to prevent the onset of CINV⁵. Beyond that, doctors have a number of pharmacologic agents at their disposal.

In addition, there are pharmacological remedies for fatigue and weakness, dietary solutions to loss of appetite and taste changes, cosmetic solutions for hair loss, and oral hygiene solutions to help prevent the development of mouth and throat sores. For more information, please see your doctor, and also check out chemotherapy side effects sheets offered by the National Cancer Institute.

References

• MedlinePlus: Drugs and Supplements search
• NCI: Managing chemotherapy side effects
• Mayo Clinic: What to expect during hair loss
• CancerNetwork: Principles of Oncologic Pharmacotherapy
• Boyiadzis, Michael M. et al. Hematology-Oncology Therapy. 2007. New York: McGraw Hill, Medical Publishing Division.