Chemotherapeutic medications are exceedingly blunt instruments. Although they prevent the fast-dividing cells in a cancerous tumor from reproducing, they also inflict collateral damage on healthy tissue that divides quickly, such as blood cells, and the cells that line the mouth, stomach, and intestines. Most of the side effects described here are consequences of impaired cell division in these regions of the body.
- The most fearsome side effect is a sluggish immune system that has lost its ability to fight off some fatal infections. Fast-dividing white blood cells that live in bone marrow are the mother lode of the immune system, and chemotherapy decimates their population. The ensuing low white blood cell counts can have consequences almost as dangerous as the tumors that chemotherapy is meant to treat: these include system wide infections like sepsis, or infections in particular areas of the body, such as shingles. Patients can try to stave off infections by washing their hands or avoiding sick people, but common-sense hygiene cannot prevent the 85% of infections caused by the naturally occurring microorganisms inside their own guts and skin, whose infectious properties would ordinarily be held in check by the immune system.
- Chemotherapy can cause anemia, a shortage of hemoglobin in the red blood cells that travel through the veins transporting nutrients to all parts of the body. It can also cause persistent and severe fatigue, which hits patients unpredictably and stays with them even after a good night's sleep. This fatigue may be the outward manifestation of anemia. When chemotherapy causes cancer patients to become fatigued and anemic, they may need to take iron supplements to increase the efficiency of the oxygen-and-nutrient transporting hemoglobin in their blood, and hormones that increase their blood production overall. In extreme cases of anemia, they may also need blood transfusions.
- Red blood cells also contain platelets, which have two jobs: they keep the blood from clotting or thinning, and they produce the natural growth factors that enable the body to repair damage to its connective tissue. When chemotherapy destroys platelets, therefore, there are more scary side effects. These include the slow healing of wounds (because of the shortage of growth factors), and the tendency to bleed and bruise easily. Without platelets, blood becomes thin and runny and won't clot around cuts and bruises; it gushes out of the body instead. Platelet transfusions can help counteract these symptoms, but often the solution is to postpone chemotherapy until platelet production returns to normal.
- VOMITING and NAUSEA are among the most feared side effects of chemotherapy. However, they are temporary, and usually disappear within a week of finishing treatment. Moreover, a class of recently developed drugs called anti-emetics can prevent vomiting before it starts, or control existing nausea and vomiting. The 5-HT3 inhibitors are the most effective anti emetics: they block brain signals that cause nausea and vomiting. According to some studies, cannabinoids derived from marijuana can also reduce vomiting and diarrhea during chemotherapy, so that patients can continue to eat. Some oncologists recommend natural or medical marijuana for this purpose. Patients may also be able to soothe their stomachs by eating small and frequent meals, or drinking plenty of clear liquids and ginger tea.
- In addition to Nausea and vomiting, diarrhea or constipation are two other common side effects of the chemotherapeutic medications that kill fast-dividing cells. These conditions, in turn, can provoke a cascade of other side effects. Patients become malnourished or dehydrated because they aren't eating and drinking enough, or because gastrointestinal damage provokes frequent vomiting. They may lose weight rapidly.
- Since hair follicles are among the fastest dividing cells in the body, medications that kill rapidly dividing cells usually result in dramatic hair loss or hair thinning. The effects are temporary: a month or two after chemotherapy treatment ends, hair usually begins growing back, although it may be more curly than before. Survivors sometimes call this side effect "Chemo perm."
- Chemotherapy doesn't just kill off hair follicles, skin cells, stomach lining, and the blood cells inside bone marrow. It can also damage vital organs such as the heart, the liver, the kidneys, and the inner ear, by inhibiting their ability to divide. Other body parts that get damaged can include the skin, the inside of the mouth, and the reproductive organs -- hence a host of lesser side effects such as red skin, dry skin, damaged fingernails, dry mouth, infertility (which can be permanent) and sexual impotence. Chemotherapy drugs damage even the capacity to reason. Cancer patients frequently describe cognitive problems such as the inability to concentrate, and patient groups have baptized this side effect "chemo brain."
- When chemotherapy does its job well, tumors die; even large tumors such as lymphomas are killed off. But they don't receive a proper burial. Instead, they break down and their toxic remnants spread throughout the bloodstream, sometimes poisoning the patient. This potentially lethal side effect is called tumor lysis syndrome. It can be prevented when patients take a prophylactic, but if it is not treated, the patient can die -- again, not of the cancer itself, but of the side effects of the treatment to kill the cancer.
- As if all this were not enough to convince you that the cure can be worse than the disease, sometimes chemotherapy actually provokes a new form of cancer after killing the old cancer in a condition known as "secondary neoplasm." The most common form of this is "secondary acute myeloid leukemia," which develops primarily after treatment with medication such as alkylating agents or topoisomerase inhibitors.[15] There is evidence of that people who've been treated for cancer with this medicines have 13.5 times as many incidences of leukemia as the general population in the 30 years following their initial treatment.
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