In 2022, around 22 cases of cancer were diagnosed, and 9.2 million people globally succumbed to the disease. Cancer–a horrific disease–continues to devastate the lives of millions around the world with no clear cure. Cancer dates back to the Egyptians in 3000 BC. The Edwin Smith Papyrus is a copy of one of the oldest medical textbooks in the world and was a manual on trauma surgery. In this, there were cases in which 8 tumors were found on the breast area, which were then removed using a “fire drill.” The text explicitly stated that “There is no treatment.” It is shocking that despite the rise of modern technology, which utilizes effective drug delivery through nanoparticles or AI, cancer still has no cure. With this being said, there have been many advances in the chemotherapy realm, and I believe it is worthwhile to acknowledge these life-changing drugs.

What is Cancer?
Cancer takes the form of around 100 evils; some affect your blood, while some affect your bones. Although different forms of cancer have different features, a general definition of this disease is uncontrolled cell growth, which can spread throughout the body. Cancer can be caused by genetic and environmental factors, but all forms of cancer affect how cells grow and divide. Cells are the fundamental unit of life, and there are around 30–37 trillion of them in your body! Your cells are controlled by genes that tell them to grow and die. Cancerous cells do not respond to your genes, which can cause things like tumors.

While this was more of a general explanation, I believe a narrower one is necessary. To begin, the behavior of a human cell is controlled by the DNA, which is condensed and arranged into chromosomes, which are located in the nucleus. The order and arrangement of the DNA tell the cell how many and how much protein it should produce. As you can predict, when an alteration appears in the DNA sequence—a mutation—it can disrupt protein production, which contributes to tumor development and progression. The majority of people believe that mutated genes are hereditary. While this is true, only 10% of cancer cases are linked to inherited genetic mutations. On the other hand, the rest consist of errors in cell division and multiplication due to environmental factors.

Chemotherapy Drugs
You might be wondering what chemotherapy drugs are in the first place. Like the name suggests, chemotherapy drugs are the medicine used for chemotherapy in cancer patients. These drugs are able to kill cancer cells, which grow and multiply rapidly. Like mentioned before, unlike regular cells, cancer cells do not die when they are no longer needed, which allows them to multiply and potentially form tumors. There are around 100 different kinds of chemotherapy drugs which are specially designed to address different types of cancer. They are organized in six main categories: alkylating agents, antimetabolites, topoisomerase inhibitors, anti-tumor antibiotics, mitotic inhibitors, and corticosteroids.

Alkylating agents attach to the DNA. As you may know, the DNA is made of a double helix structure, so these chemotherapy drugs produce strong bonds between the two strands. This prevents the two strands from splitting which in turn prevents the cancer cells from making copies of DNA. This process aims to reduce the cancer cells from multiplying. Antimetabolites are trickier! Antimetabolites disguise themselves as building blocks of DNA, which cancer cells (and normal cells) need to copy to multiply. When cancer cells use the antimetabolites, an error is made in their genetic code, which prevents the cancer from correctly copying its DNA. This stops the cancer from spreading. Like its name suggests, topoisomerase inhibitors counteract the work of an enzyme named topoisomerase. Topoisomerase is responsible for untangling the DNA, uncoils and joining them back together. Topoisomerase inhibitors prevent the enzyme from connecting the strands together which hinders progression in the DNA replication process. Anti-tumor antibiotics is a more general term for four different kinds of antibiotics: bleomycin, dactinomycin, mitomycin, and anthracyclines. The main goal of these drugs is to damage the DNA of cancer cells. Now, unlike the chemotherapy drugs previously mentioned, mitotic inhibitors deal with chromosomes. When a cell divides, tiny filaments line up the copied chromosomes along the center of the cell so when the cytoplasm splits each new cell has identical copies of the DNA. Mitotic inhibitors wreak havoc by botching the order of the filaments which prevents the cell from dividing properly. Finally, corticosteroids do not kill cancer cells directly but they do help enhance the patient’s quality of life who is battling cancer. Corticosteroids can help improve the patient’s appetite, sickness, and swelling.

The History of Chemotherapy Drugs

1940s–1950s
World War II was responsible for a lot of damage, including the lives of 75 million civilians and soldiers. But what if I told you that out of this devastating era of terror, a new light for cancer recovery emerged? It all started when sulfur mustards were accidentally spilled on troops from Bari Harbor. It was found that the bone marrow and lymph nodes were rapidly decreasing in those exposed to the mustard gas. Yale pharmacologists, Alfred Gilman and Louis Goodman were determined to examine potential benefits of the mustard gas chemicals. Through a study done with mice with a transplanted lymphoid tumor, they saw severe regression of the tumor. Knowing this, they were able to convince Gustaf Lindskog—a thoracic surgeon—to use nitrogen mustard as a treatment for a patient with non-Hodgkin’s lymphoma in 1943. Many regressions in lymphoma patients were observed and when the study was officially published in 1946 it set off waves of testing for new alkylating compounds! This study in particular was beneficial to the U.S., who witnessed widespread use of nitrogen mustard in lymphoma patients after 1946.