Chemotherapy

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The goal of all chemotherapy drugs is to kill the cancerous cells, while using a dose that causes the least harm the body's healthy cells. To achieve this goal, scientists tried to identify characteristics that are unique to cancer cells and are not found on normal tissue. A distinct cancer cell trait could serve as a potential target for a chemotherapy drug and thereby spare normal tissues. One feature that is seen in most cancer cells is that they grow at a rate faster than normal cells. Therefore, targeting some aspect of the cell growth cycle seems reasonable. Fast-growing cells would be affected the most and slow-growing cells would be least disturbed. In fact, that is the basis for many chemotherapy agents. This is apparent when considering the side effect profiles of most chemotherapy drugs. Hair follicles, skin, and the cells that line the gastrointestinal tract are some of the fastest growing cells in the human body, and therefore are most sensitive to the effects of chemotherapy. It is for this reason that patients may experience hair loss, rashes, and diarrhea, respectively.

The human body processes and excretes all drugs through either the liver or the kidneys. Therefore, when a patient has kidney or liver damage, giving chemotherapy becomes precarious. Administering the recommended amount of drug may prove to be too toxic in a patient unable to metabolize and excrete it. The pharmacokinetics (how the body handles a drug) for cancer patients are very complex, and chemotherapy pharmacology is a subspecialty on its own. Unfortunately, kidney and liver damage often result due to cancer invasion, possibly limiting the patient's chemotherapy options.

Pharmacokinetics is further complicated in cancer patients, as they are often taking multiple medications, some of which have overlapping metabolic pathways and side effect profiles. An example of this difficult situation is in the brain cancer patient. Because brain tumors often present with seizures, many of these patients take anti-seizure medications. Anti-seizure medications are metabolized by the liver and affect the metabolism of many chemotherapy drugs. Dose adjustments are an absolute necessity to avoid toxicities or sub-therapeutic dosing (doses that are too low) in these patients.

Risks of Chemotherapy:

The side effects of chemotherapy are,

1. Constipation

2. Fatigue

3. Hair loss

4. Reduces in blood count

5. Loss of apatite

6. Shortness of breath

7. Taste changes during cancer therapy

Long-lasting and late-developing side effects

Chemotherapy drugs can also cause side effects that don't become evident until months or years after treatment.

Late side effects vary depending on the chemotherapy drug, but can include: