A simple guide to understanding chemo

Chemotherapy, or "chemo," is a type of medical treatment. Chemo works by stopping or slowing cell growth. While it is most commonly thought of as a cancer drug, chemotherapy can also be used to help treat immune system conditions like rheumatoid arthritis. In the case of cancer, the disease occurs when abnormal cells develop and then reproduce. These cells are problematic because they can multiply quickly while also preventing new healthy cells from growing. The cancerous cells are also able to travel through the body. 

As a therapy, chemo can be quite effective in stopping the growth of cancer. However, its power also leads to side effects. Most people know these as hair loss, nausea, vomiting, and fatigue. This happens because chemotherapy is not a highly targeted drug. So as the agent is killing off rapidly dividing cancerous cells, healthy cells that are also rapidly dividing – like hair – are affected as well.

So… what exactly is chemo?

Chemotherapy is made up of different agents, each designed to target and kill cells. There are several categories of chemotherapies, each with a unique structure and job do to. 

• Alkylating Agents (example, cyclophosphamide): This group damages the DNA of cancer cells in order to prevent further reproduction.   
• Antimetabolites (example, methotrexate): These agents interfere with cell replication and may be used to treat leukemia as well as solid tumors.
• Antitumor Antibiotics (example, doxorubicin): These agents are commonly used against solid tumors. Made made from natural sources (like bacteria), these also interfere with DNA replication.
• Mitotic Inhibitors (example, paclitaxel): This group is made up of plant-based compounds that seek to stop cell division and are used with blood cancers and solid tumors.
• Topoisomerase Inhibitors (example, etoposide): Also plant-based, these drugs ultimately interfere with cell division. 

How is it given?

Chemotherapy is administered in several ways depending on the drug and the need. Most commonly chemo is given as an intravenously (through a vein). This infusion can happen through an IV line which may be temporarily placed, or through a central line port that stays in for a long period of time (usually several months). This option provides direct access to a vein though an implanted access device. There are also chemotherapy agents that can be taken orally, like a pill, or as an injection. 

Chemotherapy is given in cycles. At the start of treatment, a protocol will describe the number of “rounds” of chemo that are anticipated. Chemo is typically administered every few weeks. A single infusion dose may last from minutes to hours over a day. A round of chemo may require up to several days of treatments. Once a round is complete, there is a break of a few weeks for the body to recover while the chemo is working on eliminating cancer from the body. 

How are side effects managed?

Oncology and hematology teams are very knowledgeable about the side effects a specific chemotherapy may result in. As such they strive to be proactive preventing as much discomfort as possible. Typically medicines are given alongside chemo to limit feelings of nausea and other negative effects.  These may include:

• Antiemetics: These drugs help prevent nausea and vomiting.
• Steroids: These can help reduce inflammation (as well as feelings of nausea).
• Antidiarrheals and/or Laxatives: Chemo can lead to changes with bowel habits so medicine to prevent issues are often given as a preventive measure. 

What happens after chemo?

After each round of chemo, patients are monitored through bloodwork. Chemo makes a person immune-compromised and blood tests show to what degree. This must resolve prior to any further chemo treatment. After a round of chemo, patients are encouraged to limit their contact with others while their immune systems are low given the increased risk for infection. A patient who develops a fever between rounds will likely need to be seen by a doctor to make sure there is not an infection present. During this time a patient may be given medicine known as a colony-stimulating factor. This helps to encourage neutrophil (white blood cell) production. These cells are key for helping to stave off infection. 

Once all rounds of chemo are complete, the patient will be evaluated to understand if the treatments led to the desired outcome – to kill, control, or shrink cancerous cells. From here the treatment plan may go in several different directions: surgery, radiation, immunotherapy, or in the case of some blood cancers, a bone marrow transplant.

Chemotherapy is an important tool for cancer treatment. Clinical research continues to look at ways to reduce the side effects of chemo as well as how different chemotherapies may be combined in order to increase overall effectiveness. If you have questions about chemo, be sure to talk to your care team who can also give recommendations for how to prepare for the treatment.