During World War I, the horrors of trench warfare introduced a toxic weapon known as mustard gas. Soldiers exposed to this gas faced severe respiratory issues, eye damage, and painful skin blisters. In the quest for an antidote, scientists discovered that mustard gas significantly damaged the bone marrow, impairing its ability to produce blood cells.
This alarming realization led researchers to ponder whether the destructive properties of mustard gas could be repurposed to combat cancer. By the 1930s, they began injecting compounds derived from mustard gas into the veins of cancer patients. Over time, this experimentation paved the way for the first chemotherapy drugs by the end of World War II, and today, there are more than 100 different chemotherapy drugs available.
The Mechanism of Chemotherapy
Chemotherapy involves the use of cytotoxic agents—compounds that are toxic to living cells. While these medications affect both cancerous and healthy cells, they predominantly target rapidly dividing cells, a key characteristic of cancer. For example, alkylating agents, among the first chemotherapy drugs, are delivered through injections into the bloodstream. Once inside the body, these agents damage the DNA of cancer cells when they attempt to replicate, leading to cell death unless the damage is repaired. Cancer cells, which multiply quickly, absorb these agents in larger quantities and often lack the ability to repair the damage effectively, resulting in their death.
Another class of chemotherapy drugs, microtubule stabilizers, prevents the disassembly of microtubules—tiny structures that play a crucial role in cell division. By keeping these structures intact, microtubule stabilizers block the cell from completing its replication, leading to cell death.
Side Effects and Management
Despite the effectiveness of chemotherapy, it also affects healthy cells that regenerate rapidly, such as those in hair follicles, the mouth, the gastrointestinal lining, and bone marrow. This widespread impact results in common side effects like hair loss, fatigue, nausea, and vomiting. To help manage these side effects, doctors may prescribe anti-nausea medications or employ devices like cold caps, which lower the temperature around the head to reduce drug absorption in hair follicles. Fortunately, once the chemotherapy treatment concludes, the healthy tissues that were affected typically recover.
The Impact of Chemotherapy
In 2018, over 17 million people worldwide received a cancer diagnosis. Chemotherapy and other treatments have significantly improved survival rates. For instance, up to 95% of individuals with testicular cancer now survive, thanks to advances in treatment. Similarly, about 60% of patients under 60 with acute myeloid leukemia achieve remission following their initial chemotherapy phase.
Research continues to develop more targeted therapies that focus solely on cancer cells, aiming to enhance survival rates while minimizing harm to healthy tissues. This ongoing work promises to make chemotherapy an even more effective tool in the battle against cancer.