Dental Pharmacology Cancer chemotherapy

Cancer Treatment Overview

• Adjuvant therapy complements other treatments like surgery and radiation.
• Chemotherapy disadvantages include severe side effects, risk of resistance, and impact on healthy cells.
• The primary goal of curing cancer treatment is to eradicate the disease completely.

Tumor Cells and Disease Symptoms

• A high number of tumor cells correlates with the onset of disease symptoms.
• Approximately 1 million tumor cells are needed for symptoms to manifest.
• Cells that closely resemble normal cells pose identification challenges for the immune system.

Treatment Recommendations

• Large gastrointestinal stromal tumors (GIST) are best treated with surgical resection followed by imatinib.
• Colorectal cancer typically follows a sequence of surgery, potentially chemotherapy, and targeted therapies.
• Osteogenic sarcoma treatment often starts with chemotherapy followed by surgery.

Contraindications and Treatment Strategies

• Hormonal therapy is contraindicated when surgery and radiation are ineffective due to tumor size.
• The Skipper Hypothesis suggests that repeated dosing with the same drug results in a constant proportion of cell death.

Chemotherapeutic Agents

• 5-Fluorouracil (5-FU) inhibits thymidylate synthase as its mechanism of action. Its administration route is intravenously or orally.
• Common indications for 5-FU include colorectal cancer and head and neck cancers. Delayed toxicities involve myelosuppression and hand-foot syndrome.

Methotrexate Insights

• Methotrexate primarily inhibits dihydrofolate reductase, impacting folic acid metabolism. It is administered either intravenously or orally.
• Indications for Methotrexate therapy include lymphomas, leukemias, and certain solid tumors. Adverse effects can range from hepatotoxicity to myelosuppression.
• Leucovorin rescue mitigates toxicity in high-dose Methotrexate therapy.

CYTARABINE and Purine Antagonists

• CYTARABINE primarily targets the S phase of the cell cycle, inhibiting DNA synthesis.
• Adverse effects of CYTARABINE can include myelosuppression and nausea. Recommended schedules vary based on the treatment regimen.
• 6-Thioguanine (6TG) and 6-Mercaptopurine (6MP) are used for acute leukemia, with common adverse effects involving liver toxicity and risk of infection.

Supportive Therapies

• Allopurinol is used in supportive therapy to manage hyperuricemia due to cell turnover from chemotherapy.

Specific Drug Actions and Toxicities

• Vincristine acts as a spindle poison, disrupting microtubule formation and leading to mitotic arrest.
• Common agents include doxorubicin for systemic Hodgkin's disease and bleomycin as part of combination therapy for acute leukemia.
• Drugs like paclitaxel are indicated for breast and ovarian cancer, while tamoxifen is utilized for breast and prostate cancers.
• Delayed toxicities such as alopecia or hematologic effects can occur with various chemotherapeutic agents.

Drug-induced Toxicity

• The oral cavity is especially susceptible to drug-induced toxicity due to rapid cell turnover and exposure.
• Alkaloid derivatives of plants often act by disrupting microtubule function during the cell division process.
• Acute effects of vinblastine toxicity can include neurotoxicity, nausea, and anti-mitotic effects.

Key Mechanisms of Action

• The mechanism of action for alkaloids includes interaction with tubulin to inhibit mitotic spindle formation, crucial for cell division.

Miscellaneous Findings

• Specific drugs that lead to delayed toxicities include vincristine and doxorubicin, both of which also have acute side effects such as nausea and bone marrow suppression.

Test your knowledge on the general principles of adjuvant therapy for gastrointestinal stromal tumors (GIST) and colorectal cancer. Learn about the use of chemotherapy as an adjunct to surgery and radiation, as well as when surgery and radiation may be contraindicated. Discover the importance of preparative therapy and the role of chemotherapy in reducing tumor size prior to other treatments.