The first advances in chemotherapy were taken in the 1940's when doctors started to use chemicals like folic acid inhibitors and nitrogen mustards. That was the beginning of a new way of cancer treatment and several other diseases. Since those times many different substances were developed and chemotherapy turned into pretty big industry.
For all the presently available chemotherapy types the basic principle is simple - to slop or at least to slow the cell division (as long as cancer is uncontrolled cell division due to DNA mutations). Although there are different types of drugs used in chemotherapy slowing the mitosis they all are targeting cells that divide pretty fast. This quality affects cancer cells quickly.
The huge variety of different drugs can be divided in to groups. These are alkylating substances (they add so-called "alkyl" to all the electronegative groups in cell), plant alkaloids (they stop microtubule function in cell thus preventing cells from division), topoisomerase inhibitors (topoisomerase is a very important part in the process of combining the DNA, so without it cell would not be able to reproduce properly) and antitumor agents of different sorts.
But even though most of the drugs for the chemotherapy have targeting effect they also affect normal body cells that also divide fast (like hair cells for example). That is why all the chemotherapy types are potentially dangerous for the patient. And because of the chemotherapy side effects (like hair loss, anemia, hemorrhage and others) the choice of drugs dosage has to be made personally for each patient and this procedure needs being performed with great care (with wrong dosage chemotherapy would be not effective or too harmful for the patient).
To low the potential damage different schemes and chemotherapy types are applied during the treatment. Today among different chemotherapy types you can meet three basic schemes of the procedure: "combined modality chemotherapy", "adjuvant chemotherapy" and "halliative chemotherapy".
The latest achievements in technology allowed producing special drugs for chemotherapy that are not actually affecting DNA. Such substances as imatinib mesylate affect directly those abnormalities that are present only in cancer cells.
For professionals there is a special chemotherapy type review where new drugs and schemes are described. So, if you want to know about all the latest techniques in the area you should read this review.
But still no matter how advanced the drugs are and what chemotherapy types undesirable side effects are present and for chemotherapy to be perform a patient needs to have a good general health.
In most of the hospitals to lessen the damage of chemotherapy and get better results in fighting cancer chemotherapy is usually combined with other treatment methods like surgery or radiation therapy. Chemotherapy can also be used for the treatment of other diseases not related to cancer. All kinds of autoimmune diseases and transplant rejections can be also treated using this technique.
Until a more "user-friendly" method of treating cancer is developed, chemotherapy will continue to be used as the first line of defense in the battle against the disease of cancer.