Chemotherapy

What is a big difference between human and pet chemo?

Pets is well tolerated with only 20% experiencing toxicities and <5% have severe toxicity

What is gompertzian growth?

Small tumor means rapid cell division

Large tumor means slower cell turn over

What do cancer treatments target?

Rapidly dividing cells

How do you treat a local cancer (stepwise)?

1. Surgery

2. Chemo

3. Radiation

How do you treat a systemic cancer (stepwise)?

1. Chemotherapy

2. Immunotherapy

3. Surgery or RT

T/F some cancers also require systemic chemo after Sx to prevent the spread?

True

What are the goals of chemotherapy?

Palliative care (not a cure)

Maximize survival while maintaining good quality of life

What are does palliative care and maximizing quality of life look like?

Control microscopic disease

Delay progression and metastasis

When should we use chemotherapy?

Systemic/disseminated disease

Documented metastasis

Microscopic disease after surgery

Tumor reduction before surgery

Radiation sensitization

What is neoadjuvant surgery?

Tumor reduction with chemo before surgery

What is adjuvant therapy with chemo?

Use chemo after surgery or radiation therapy

When do we not use chemotherapy?

Organ dysfunction (drug metabolism is altered)

Substitute for surery

What is chemo not a good substitute for surgery?

Chemo is not a primary treatment for the majority of tumors

What are the cells that are side effects of chemo?

Bone marrow

Hair follicles (alopecia)

Intestinal epithelium (GI)

BAG side effects

What should you focus on when evaluating chemo drugs?

What sets that drug apart from the others

What is the efficacy of chemotherapy?

depends on dose X time

What are results of chemo affected by?

Drug used

Dosage

Number and frequency of treatment

What is metronomic chemotherapy?

Continual, low dose that is oral combined with an NSAID

What is the target for metronomic chemotherapy?

Angiogenesis (cut off blood supply)

What is the goal of metronomic chemotherapy?

Slow progression and metastasis

What is the benefit of metronomic chemo?

Less severe and fewer toxicities 

What are indications for metronomic chemo?

Incompletely resected soft tissue sarcoma, hemangiosaroma

What is an example of metronomic chemo?

Cyclophosphamide + deracoxib

How do tumors get chemo resistant?

P-glycoprotein pump that removes toxins increasing drug export out of cells

Natural substances 

Also drug clearance, decreased drug activation, altered drug targets

What breeds are susceptible to MDR1 mutations?

Collies, Australian Shepherds

T/F most chemo drugs are affected by MDR1 mutated dogs?

True

How do you dose chemo?

Based on body surface area (BSA) in m² unless patient is <10kg

T/F someone should always check you chemo dose calculations?

True

How should you round chemo drugs?

Always round down (for the most part lol)

How do you determine response to chemo?

Repeat exams and staging diagnostics every other treatment (6-8 weeks)

Compare tumor measurements 

Why is it important to compare tumor measurements during treatment?

Remission status influences treatment decisions

What is a complete response (CR)?

Disappearance of all target lesions

Pathologic LNs <10mm short axis

What is a partial response to chemo?

>30% reduction in sum of diameters of target lesions

What is a stable disease response?

<30 reduction

<20 increasei n sum of diameters of target lesions

What is a progressive disease?

>1 or more new lesions

>20% increase in sum of diameters of target lesions

What should you do if you are monitoring response and get a progressive disease?

Switch your drug!

What should you do if you have a stable disease response?

Can consider switching based on alternatives

What is the concern of neutropenia with no C/S off illness?

Nothing

What is the concern with neutropenia and fever?

Emergency! High risk of sepsis as neutrophil count decreases

What happens if there are no more neutrophils?

There will not be a fever

What are some sources of infection while on chemo?

GI tract translocation

Other foci like pneumonia, UTI, surgery, radiation site, IV catheters, implants

What is a grade 1 neutropenia scale?

1500 - LLN cells

What is a grade 2 neutropenia?

1000-1500

What is a grade 3 neutropenia?

500-1000

What is a grade 4 neutropenia grade?

<500

When is risk of septicemia the greatest?

<1000 neutrophil count

What breeds are more likely to get alopecia?

Poodles, terriers, old english sheep dogs, bichon, maltese

How does alopecia manifest?

Loss of whiskers and eyelashes (common)

Slower hair regrowth

When do you delay chemotherapy?

<2000 neutrophils or <75000 platelets

UNLESS myelopthisis due to disease, and certain drugs

When do platelets and neutrophils get to nadir (their lowest point)?

5-7 days after treatment

If a patient has <1000 neutrophils what do you do every time?

Start antibiotics and dose reduction

If a patient has <1000 neutrophils and fever what do you do?

Hospitalize, fluids, antibiotics, dose reduction

If a patient has 1000-2000 neutrophils and does not have a fever what do you do?

Nothing

If a patient has 1000-2000 neutrophils and does have a fever what do you do?

Hospitalize, fluids and antibiotics

What oral antibiotics are good?

Clavamox

TMS

Enrofloxacin or cephalexin

What IV antibiotics are good?

Timentin or unasyn

Ampicillin/cefazolin and enro

Ampicillin/cefazolin and aminoglycoside

Enro and metro

What can you use prophylactically to prevent nasea

Cerenia, metro, zofran, reglan

What is the MOA for GI upset due to chemo?

Direct damage to epithelial cells (3-5 days to move from crypts to villi)

Stimulation of CRTZ/vomiting center

What can you use to treat chemo diarrhea?

Canalevia (sepcific for chemo diarrhea)

Metro, imodium

What does cyclophosphamide cause?

Sterile hemorrhagic cystitis

What does lumstine do?

Hepatotoxicity, significant myelosuppression

Monitor ALT, denamarin

What does cisplatin do?

Nephrotoxicity and ototoxicity

Fatal pulmonary edema in cats

What does vincristine do?

Neurotoxicity and vesicant

What does rabacofosadine do?

Skin and pulmonary fibrosis

What does 5-FU do?

Fatal neurotoxicity in cats

What does doxorubicin do?

Cumulative cardiotoxicity

Nephrotoxic in cats

Severe vesicant

Anaphylaxis