How Is Chemotherapy Used for Prostate Cancer?

Chemotherapy is a systemic (meaning whole body) treatment option indicated for many different types of cancer and other conditions. Chemotherapies indicated for cancer treatment are drugs that have antineoplastic properties, meaning that they act to prevent or halt the development or growth of tumors. Chemotherapies can be used at various points in the treatment process and can be utilized with the intention to cure or control a cancer, or as a palliative care option to treat pain. Chemotherapies can be taken orally or via an intravenous (IV) injection, depending on the drug. The frequency and amount of chemotherapy taken can vary on a case by case basis. You may receive only one chemotherapy agent at a time, or multiple chemotherapy agents, since they can work differently. These decisions typically depend on an individual’s age, stage, type or location of cancer, other health conditions, prognosis, and ability to tolerate side effects.^1,2

How does chemotherapy work?

Chemotherapies often act to disrupt the cell cycle, the process responsible for the creation and growth of new cells. When a parent cell is unable to create or split into two daughter cells, it will eventually become too faulty and will die. When a cell manually kills itself because of a faulty cellular process it is called apoptosis. Chemotherapies cause cancer cells to stop dividing and undergo apoptosis, thus, slowing or halting the growth of a cancerous mass. Cancerous cells are dividing more rapidly than most other cells in the body. This property is what increases the chances of chemotherapies targeting cancer cells. However, there are still a few kinds of cells in our body that divide rapidly, such as hair cells or cells that line our intestines, which explains the common side effects of hair loss or gastrointestinal disruption while on a chemotherapy medication.

Blood cells, including important white blood cells, red blood cells, and platelets, also divide on a somewhat regular basis, making it important to closely monitor someone on chemotherapy to make sure their blood cell counts aren’t dangerously low. If a person’s blood cell count dips below a certain threshold, they may be unable to receive chemotherapy until the issue has resolved. Additionally, steroids like prednisone can be used with chemotherapies to increase their effectiveness when it comes to targeting and killing cancer cells as well as to help with pain management and to help manage some of the side effects of chemotherapy.^1-5

Types of chemotherapy

Chemotherapies can be used on their own as a primary therapy (meaning an initial treatment option), or in combination with other treatment options including radiation, surgery, or hormone therapies. When chemotherapy is used in addition to or after another treatment option, like radiation or surgery, it is considered an adjuvant therapy. If chemotherapy is used to control or shrink tumors prior to surgery or radiation therapy, it is considered a neoadjuvant therapy. Chemotherapy may also be used for cancers that are recurrent (returned). The two main types of chemotherapies utilized for prostate cancer either target the microtubules of a cell, or the cell’s DNA replication process.

Chemotherapies that target microtubules

Some chemotherapies target a cell’s microtubules and prevent them from being able to perform their role. Microtubules play a key role in allowing cells to divide into two cells during the replication process. By blocking this process, a cell is unable to complete a replication cycle (or divide), and will eventually die. Examples of this type of chemotherapy include:

• Cabazitaxel (Jevtana^®)
• Docetaxel (Taxotere^®)
• Estramustine (Emcyt^®)

It is important to note that Emcyt^® also has estrogenic effects on tumor cells, and individuals taking this medication should also be monitored for blood clots. Additionally, individuals taking Jevtana^® and Taxotere^® should be monitored for possible nerve damage.

Chemotherapies that target the DNA replication process

Some chemotherapies are designed to inhibit a key component of the DNA replication and damage repair process. This type of therapy also inserts itself into DNA to cause strand breaks. When a parent cell is unable to replicate its DNA successfully, it cannot split into two daughter cells, and the cell line will die. Additionally, when DNA damage becomes too great, the cell will eventually become too faulty and will die.

• Mitoxantrone (Novantrone^®)

Individuals on Novantrone^® should be monitored for the development of cardiovascular complications and the development of a second cancer called acute myelogenous leukemia (AML).^1,3,5,6

Side effects of chemotherapy

The exact side effects vary based on the chemotherapy taken, but general side effects of certain chemotherapies include:

• Hair loss or thinning
• Nausea and vomiting
• Diarrhea
• Loss of appetite
• Fatigue
• Decreased blood counts

These are not all the possible side effects of chemotherapy. Talk to your doctor about what to expect or if you experience any changes that concern you during treatment with chemotherapy. There also may be additional treatment options you can be prescribed alongside your chemotherapy to manage specific debilitating side effects. Additionally, red and white blood cells and platelets are regularly dividing cells, and therefore, can become accidental targets of chemotherapy. For this reason, there is a heightened risk of developing serious infections while on certain chemotherapies, as well as easy bruising or bleeding. Many of these side effects are reversible and may improve after completing treatment. It is also important to ask your doctor about what to expect with any other medications you may be taking alongside your chemotherapy.^1-3

Areas of interest

Research into chemotherapy treatment options for prostate cancer is focused on creating new, more effective chemotherapy medications, as well as to determine the highest standard of chemotherapy treatment for different cases of prostate cancer. This includes determining optimal combinations of chemotherapy with non-chemotherapy treatment options, as well as the optimal time to begin chemotherapy.^6-7