Blue Book: Chemotherapy principles

Question 1

Give three reasons why cytotoxic chemotherapy is used in combinations of different drugs?

Answer 1

1. ‘Synergism’ different classes of drugs have different actions and can kill more cancer cells.
2. Less chance of drug-resistant malignant cells emerging.
3. Drugs used have different sites of toxicity are combined, the doses can still be maintained.

Question 2

When are single agent chemotherapy appropriate?

Answer 2

Palliative setting.

Question 3

Why is chemotherapy given cyclically?

Answer 3

To allow normal cells to recover from the toxicity.

Question 4

Which cells are most affected by standard dose chemotherapy?

Answer 4

• Haematopoietic stem cells
• Lining of GI tract
• Produce low blood counts ‘myelosuppression’
• mucositis

Question 5

How long is required for the cells to recover.

Answer 5

3-4 weeks.

Question 6

Why are repeated of cycles of chemotherapy required?

Answer 6

As any cycle may only kill a proportion of the tumour cells. Therefore repeated cycles are required to get tumour clearance.

Question 7

Why do we not give endless cycles of chemo?

How long are many treatments maximally effective after?

Answer 7

Doesn’t prevent resistance emerging and increases toxicity.

6 month course.

Question 8

How are conventional doses of chemotherapy drugs decided

Answer 8

Effective against particular malignancy.

Majority of patients cause tolerable side effects.

Question 9

When are toxic high doses used? Give 2 example cancers.

What support do these patients need?

Answer 9

In conditions when long term survival or cure are possible, such as Hodgkins disease and Ewings Sarcoma.

Question 10

Maintenance prolonged chemotherapy has little advantage in what tumours? Why?

When is it used?

Answer 10

In solid tumours as resistant clones soon develop and toxicity increases.

Prolonged chemotherapy is used in childhood leukaemia for 18 months following the induction of a complete remission.

Question 11

Advantages and disadvantages of oral chemotherapy.

Which drugs can be given orally.

Answer 11

Advantages: freeing the patient from hospital visits and invasive procedures.
Disadvantage: doesn’t reduce toxicity and regular review is still required. Variations in the levels of drug circulating based on whether and when the drug was taken can be promblomatic.

Cyclophosphamide, etoposide, capecitabine, tamoxifen.

Question 12

Name 3 methods of administering systemic chemotherapy.

Answer 12

1. Intravenously as bolus injection
2. or short infusion.
3. Continuous infusion via central venous line.

Question 13

Name threes regions of the body where chemotherapy can be directly infused?

What is the benefit of this method?

Answer 13

1. Intravesical: Superficial bladder cancer.
2. Intraperitoneal: into the peritoneal cavity for tumours that can spread trans-coelomically.
3. Intra-arterial: Any tumour that has a well-defined blood supply e.g. hepatic artery infusion for liver metastases.

High doses at site of tumour with negligible systemic absorption and minimal toxicity.

Question 14

Most chemotherapy doses are determined by which patient factor?

How is the dose for carboplatin decided?
What about new drugs such as monoclonal antibodies, e.g. trastuzumab?

Answer 14

1. Body surface area (BSA)
2. Depending on renal function.
3. Body weight alone

Question 15

Chemotherapy can be in 6 ways, what are they?

Answer 15

1. by injection or drip into a vein (intravenous chemotherapy)
2. oral chemo
3. by injection: intramuscular or subcutaneous
4. Intrathecal chemo (into spine or brain)
5. Into a body cavity eg the bladder
6. directly to the skin for some skin cancers.

Question 16

Name 4 methods that intravenous chemotherapy can be given

Answer 16

• cannula
• a central line (hickman) (long tube inserted into a vein in chest)
• a PICC (percutaneous inserted central catheter)
• an implantable port (portcath) put into a vein and has opening (port) under skin of the chest.