2 Chemotherapy Flashcards
List some of the available treatment options for cancer
- Surgery
- Radiation therapy (Radiotherapy)
- Chemotherapy
> Neo-adjuvant - (chemotherapy before surgery or radiation therapy)
> Adjuvant - (chemotherapy after surgery or radiation therapy) - Palliative care
Describe the use of chemotherapy treatment
Chemotherapy - the use of drugs to manage malignances
- Cancer cells are similar to host cells so are difficult to target
- Cancer cells are usually rapidly dividing - so target DNA synthesis and mitosis
What type of drugs does chemotherapy use?
They use cytotoxic drugs; which rapidly kill dividing cells
- This is carried out in cycles: induction and maintenance phases
- The doses are based on body surface area
Describe the principles of cancer chemotherapy (what is hoped to achieve?)
- Treatment/palliation
- Aim is to ‘kill’ cancer cells or prevent replication
Why are multiple drug regimens given?
- Different classes of drugs work in different ways, hence attacking different sites of cell division
- It is a way to reduce toxicity
Why is chemotherapy delivered in cycles?
- To achieve total cell kill
- To limit toxicity
- Typically, 3-week cycles
Works on the principle that with every cycle, both normal cells and cancer cells are damaged
But in the gap, cancer cells recover and grow back slower, so with each successive chemotherapy cycle, overall the cancer cell population decreases over time, leaving enough time for normal cells to grow back and recover fully
List the two different types of cytotoxic chemotherapy agents
- Cell cycle-specific (CSS) agents
- Cell cycle-nonspecific (CCNS) agents
Give some drug types of cell cycle-specific (CCS) agents
- Antimetabolites
- Plant alkaloids (vinca alkaloids, taxanes, podophyllin alkaloids)
Give some drug types of cell cycle-nonspecific (CCNS) agents
- Alkylating agents
- Antibiotics (anthracyclins)
Describe the actions of antimetabolites as a chemotherapy agent (CCS)
(give examples)
It interferes with metabolic pathways in DNA synthesis (S phase in cell cycle)
e.g. Methotrexate, 5-flurouracil
Give the mechanism of action of methotrexate (an Anti-metabolite)
Methotrexate
- It is a folate antagonist
- It inhibits purine synthesis
When given methotrexate, patients need to take folate supplements too,
- as methotrexate reduces the limited reservoir of folate in the body
Give the mechanism of action of
5-Fluorouracil (an Anti-metabolite)
5-Fluorouracil is a false substrate (a pyrimidine analog)
- 5-Fluorouracil is incorporated into DNA as false metabolites and leads to damage of DNA
Give some examples of plant alkaloids as a chemotherapy agent (CCS)
- Vinca Alkaloids (targets S and M phase)
- Taxanes (G2 and M)
- Podophyllin alkaloids (S and G2)
Give the mechanism of action of Vinca Alkaloids (plant alkaloids)
Vinca alkaloids are microtubule inhibitors (targets the S + M phase)
- e.g. Vincristine, vinblastine
- they inhibit the formation of the mitotic spindle
- This MUST be given by IV only, FATAL if given intrathecally (neurotoxin)
Give the mechanism of action of taxanes (plant alkaloids)
Taxanes are microtubule inhibitors
(targets the G2 and M phase)
- e.g. Paclitaxel
- They stabilise spindle fibers producing similar effects to vinca alkaloids
