Types of chemotherapy

Chemotherapy medicines are put into classes based on:

• How they affect substances inside the cancer cell
• Which process or activity the medicine affects in the cancer cell
• What specific point the medicine attacks a cell as it rests, grows or divides

Because some chemotherapy medicines act in more than one way, they may belong to more than one class.

Chemotherapy works by affecting DNA, the genetic material inside cells that controls how the cells work.

Your doctor may recommend treatment with one chemotherapy medicine or a combination of medicines. Knowing how each medicine works can help predict side effects and help your doctor decide which medicines will work well together, when each medicine should be given, in which order and how often. Your chemotherapy treatment plan will depend on the type and stage of breast cancer, among other factors.

In this section, you’ll learn more about the classes of chemotherapy medicines and some common breast cancer medicines within each class.

Anthracyclines

These chemotherapy medicines are made from the Streptomyces bacteria. They interfere with way DNA copies itself inside cancer cells, which stops the cells from growing and causes them to die.

Anthracyclines are given by vein and work at any point in the cell cycle, the series of steps that must happen for a cell to divide and make copies of itself. Common anthracyclines in breast cancer are:

• Doxorubicin (Adriamycin)
• Epirubicin (Ellence)
• Liposomal doxorubicin (Doxil)

Alkylating agents

Alkylating agents were one of the first classes of medicines used to treat cancer. They work by interfering with cell DNA, taking away the ability of the cancer cell to multiply.

Some alkylating agents can be given by mouth, while others are given only by vein. They work by causing damage to DNA at all phases of the cell cycle. A common alkylating agent in breast cancer is:

• Cyclophosphamide (Cytoxan)

Taxanes

Taxanes are a type of medicine that blocks cell growth by stopping mitosis, the process of cells dividing. Taxanes interfere with microtubules, the parts of the cell that help move the information inside them during mitosis. Because of this action, taxanes are considered inhibitors of mitosis, or cell division.

Common taxanes in breast cancer are:

• Paclitaxel (Taxol)
• Docetaxel (Taxotere)
• Nab-paclitaxel (Abraxane)

Other microtubule inhibitors

These medicines block cell growth by stopping mitosis, the process of cell division. They do this by interfering with microtubules, the scaffolding that helps the cell divide.

There are multiple other medicines or classes of medicines used in breast cancer that act as microtubule inhibitors. They are:

Epothilones. There is one epothilone that is FDA approved for use in metastatic breast cancer:

• Ixabepilone (Ixempra)

Vinca alkaloids. These medicines kill cancer cells by attaching to a protein called tubulin, which stops the production of normal microtubules. There is one approved vinca alkaloid for metastatic breast cancer:

• Eribulin (Halaven)
• Vinorelbine (Navelbine)

Antimetabolites

Antimetabolites are medicines that damage cancer cells by interfering with the way DNA develops inside the cells. They are similar to normal substances inside the cell, so they “trick” the makeup of the cell into thinking the antimetabolite is a normal part of the DNA. Then, the antimetabolite damages the DNA after it becomes part of the makeup. Antimetabolites work at very specific times in the cell cycle.

Common antimetabolites in breast cancer are:

• Capecitabine (Xeloda)
• Fluorouracil (5-FU)
• Gemcitabine (Gemzar)

Platinum-based chemotherapy

These chemotherapy medicines contain the metal platinum. Platinum medicines interfere with cells’ DNA, taking away the ability of the cancer cell to multiply.

Platinum-based medicines in breast cancer are:

• Carboplatin (Paraplatin)
• Cisplatin (Platinol)