がん治療薬と副作用

In Japan, about one-half of population suffers from cancer in their lives, and one-third will die of it. Currently, we have three strategies in the treatment of cancer, i.e., surgical treatment, radiotherapy, and chemotherapy（drug therapy）. Most conventional chemotherapeutic drugs work by impairing cell division, resulting in apototic cell death. However, these drugs have potent side-effects including nausea and vomiting, diarrhea and constipation, anemia, hair loss, hemorrhage, immunosupression and myelosuppression, and secondary neoplasms due to disrupt normal cell growth. Some specific anti-cancer drugs are associated with organ-specific toxicities including cardiovascular disease（e.g., doxorubicin）and lung disease（e.g., bleomycin）. In addition, anti-cancer drugs are applied to patients with maximum tolerated dose（MTD）, side-effects are intolerable to the patients in most cases. In order to improve these unpleasant symptoms, some drugs are approved to cope with the side-effects of chemotherapy（synthetic G-CSF for neutropenia, ５-HT３ inhibitors to block one or more of the signals that cause nausea and vomiting）though, medical staffs should pay attention to these sign of side effects. By the way, recent advances in molecular biology have identified numerous genes and proteins involved in malignant transformation as targets of anticancer therapy. Many moleculartargeted agents are now applied at the bedside. Successful developments of trastuzumab in treating breast cancer, imatinib in chronic myeloid leukemia（CML）and gastrointestinal stromal tumors（ GISTs）, gefitinib and erlotinib in non-small cell lung cancer, sunitinib in GISTs and renal cell carcinoma（RCC）, sorafenib in RCC, and bevacizumab in colorectal cancer, have validated the concept of molecular targeting and raised expectations of patients and oncologists alike. These drugs have high selectivity for tumor cells, provide effective treatment, and produce fewer side effects than are seen with conventional anticancer agents. However, unexpected untoward results may occur during treatment. Special attention will be required.