Basic principles of cancer chemotherapy

Basic principles of cancer chemotherapy

1. Basic principles of Chemotherapy Dr. V. S.Swathi Assistant Professor

2. For Leukaemia and Lymphomas Several phases of chemotherapy is required Cure can be achieved with aggressive therapy for a prolonged time Remission induction This is given for killing maximum number of cancer cells Consolidation/ Intensification/ Post remi ssion This is given to eradicate any clinically undetectable disease and lower the tumor cell burden below 10 3 at which host immune system can keep cancer cells in control Maintainenance This is given for maintaining or prolonging the remission

3. For Solids tumors Adjuvant therapy It is given after more definitive therapy like surgery for eliminating remaining disease or undiagnosable micro metastasis Neoadjuvant chemotherapy It is given before definitive therapy to decrease the tumor burden ( Surgery/ Radiation) Palliative therapy It is given when complete eradication of tumor is not possible or patient refused aggressive therapy. It is given to decrease tumor size, to control tumor cell growth and to reduce symptoms Salvage therapy It is given for getting remission in case of other therapies are failed

4. Dosing of chemotherapy agents Dose of chemotherapy drugs is adjusted based on: Body weight- Used in case of patient body weight is 10-11kg Body surface area- It is widely used Area under the curve plot Dose of chemotherapy agents is adjusted in case of renal and hepatic impairment patients

5. Combination therapy It is given generally to get maximum efficacy Main reasons for combination therapy: Overcoming/ preventing resistance To kill resting and dividing cells To increase effect To rescue normal cells Chemotherapy regimens are given at short course in cyclic manner

6. Acronyms are used to designate chemotherapy agents

7. Route of administration Chemotherapy agents are given in the following routes Intravenous route Oral Subcutaneous Intrathecal Intra arterial Intra peritoneal Intra vesicle Continuous IV Infusion Hepatic artery infusion Mostly IV route is used Products like liposomal/ pegylated agents are used to decrease toxicities

8. Response to chemotherapy Complete response(CR) Here all clinical, gross and microscopical changes are disappeared Partial response(PR) Here tumor size reduces to half, and lasts for reasonable period Response rate (RR) It is combination of complete and partial response RR=CR+PR Stable Disease (SD) It indicates tumor neither grows or nor shrinks significantly (Less than 25% change) Progressive Disease (PD) It indicates no response or increase in tumor size or appearance of new lesions (More than 25% change)

9. Factors affecting response to chemotherapy Tumor cell heterogenecity- Requires aggressive therapy Drug resistance- Tumor size is directly proportional to resistance Drug intensity- in case of complications dose intensity should be decreased Dose density- In case of getting more effect dose density is decreased Patient specific factors include: Poor functional status Impaired organ function Co morbid conditions