In The Venue

Chemotherapy drugs can be used to treat any kind of tumor, but they are particularly useful weapons against the malignant or high-grade tumors that could spread throughout the body if they are not destroyed.

Most chemotherapy drugs are "cytotoxic,” that is, they kill or damage fast-dividing cancer cells in order to prevent the cancer from spreading.  The inherent problem with this strategy is that it kills both the cancerous cells and the healthy cells that divide fast, such as the intestinal epithelium or lining, which protects the stomach, and the hair follicles responsible for growing our hair.  This is why cancer patients frequently lose their hair and experience severe stomach pain.  However, some drugs are easier on the body than others, and doctors can adjust treatments for some patients in order to minimize side effects while also continuing to target the tumor.   

Chemotherapy is useful, even essential, to treating many forms of cancer, but it also has severe limitations.  Tumors with cells that divide extremely quickly, such as acute leukemia, aggressive lymphoma and Hodgkin's disease, respond the most to chemotherapy.  Chemo drugs are also particularly effective at killing smaller, "younger" tumors that are still able to regulate cell growth.  Yet there are other cancers, such as "indolent lymphoma,” that can never be easily treated with chemotherapy because even the newest tumor cells have slow growth rates. 

Even with the more aggressive cancers, however, chemotherapy is most effective in the early stages.  As the tumors continue to divide, each generation of tumor cells is less differentiated and regulated than the previous one, and less responsive to chemotherapy.   As a tumor grows larger and more solid, the cells at its dense center virtually stop dividing, and become less accessible to substances from outside the body; the chemotherapeutic agent cannot touch them.  Hence, large tumors that have slowed down their pace of growth are best treated with more invasive methods such as radiation therapy or surgery.  

Moreover, recent scientific studies suggest that tumors can develop resistance to chemotherapeutic drugs. When some cancer cells are examined by microscope, their surfaces come into greater focus, and scientists can see networks of miniature biological pumps, actively moving the chemo drugs from the inside of each cell to the outside.   Even cancers are programmed to survive and reproduce.  The next line of defense in this case is to move onto more invasive forms of treatment such as radiation and surgery. 

Even so, cancer specialists continue to prescribe chemotherapy drugs because even if they do not completely cure a patient of his cancer, they may reduce the severity of symptoms and lengthen the patient's life.    Sometimes   the combination of a variety of different chemotherapy drugs, each taken at a different time of day or night can prevent the cancer from developing any drug resistance.   In other cases, chemotherapy is combined with radiation and surgery in order to target different parts of the tumor in different ways.   

Any kind of chemotherapy is hard on the body, and not all sick patients have the stamina to pursue it to the bitter end.  Only a fraction of the cells in a tumor die with each treatment, so the doctor must administer repeated doses over a long period in order to reduce the size of he tumor.   If the drugs were all administered at once, they would cause death from toxic shock. 

Some new and experimental forms of chemotherapy promise greater precision in the cells they destroy.   Engineers have recently begun designing  "specially targeted delivery vehicles,” computerized microscopic transporters that whisk chemotherapeutic agents quickly through the bloodstream to the edges of the malignant tumor, and then invade the tumor, neutralizing its antigens --or chemical defenses -- and depositing the chemotherapy drug right where it is most needed.    Rather than spray an entire area of the body with a dangerous poison in order to kill a tumor, they aim only at the tumor and interact very little with any other part of the body.   The effect of these "specially targeted delivery vehicles," then, is to allow the chemotherapy drug to kill more of the tumor and less of the surrounding cells.  Patients will then feel better more quickly and experience fewer side effects than before.