Generally, chemotherapy refers to drugs that have an anticancer effect. A number of different chemotherapeutic drugs exist, but they each fall into specific categories of use. First-line chemotherapy drugs are those treatments which are likely to be the most effective, and these are the drugs that a doctor will typically administer first. If a first-line drug doesn't work, then the patient can change to a second-line drug.
There are many types of cancer, and as chemotherapy drugs differ in their actions, only some drugs are suitable for specific cancers. Of these drugs, some benefit more people than other drugs do. Typically, when a patient finds out he or she has cancer, the doctor recommends a course of treatment that contains the first-line chemotherapy. The first choice drug can differ from cancer to cancer.
The chances of the first-line chemotherapy having a beneficial effect are generally higher than alternative drugs, which is why this drug is the first choice of the doctor. Other names for a first-line chemotherapy drug regimen are standard therapy, primary therapy and induction treatment. Sometimes the patient receives treatment that is aimed at shrinking the tumor as opposed to eradicating the tumor, and this can also be called first-line therapy.
If the first-line chemotherapy treatment is effective at shrinking a tumor, the patient may also receive extra treatment like more drugs, radiation therapy or hormones. If the initial chemotherapy does not work as well as the patient and doctor hoped, then the patient can begin taking what is called second-line chemotherapy. This type of treatment also uses drugs that are toxic to cancer cells, but these drugs have slightly different characteristics to the initial chemotherapy.
Commonly, second-line drugs have been proven to have beneficial effects on cancers that specifically do not respond to the first choice drug. Cancer cells tend to become resistant to drugs over time, as new cells grow continuously, which can have slightly different characteristics, that in some cells can render them invulnerable to the medicine. If resistance happens with the first drug, then the second drug, which may have different cell killing mechanisms to the first medicine, has a better chance of being effective.
Doctors can switch chemotherapy prescriptions if drugs are not having any beneficial effect, and a patient may also be able to opt for other forms of treatment such as surgery or radiation. New chemotherapy drugs enter the market over time, due to research and development by scientists and pharmaceutical companies, and scientists perform clinical studies and collect data on their effectiveness. If a new drug is more beneficial than an old drug, it takes its place as the first-line treatment.