Breast cancer drugs Flashcards
What are the aims of treatment of breast cancer?
Reduce mortality
Increase progression-free and disease-free survival
Improve QoL
What are the main treatment arms of breast cancer?
Surgery and radiotherapy = remove tumour mass
Adjuvant drug therapy = after surgery to reduce risk of recurrence and risk of developing invasive disease
Neoadjuvant drug therapy = before surgery to reduce size of the tumour to allow breast-conserving surgery to be possible + reduce axillary lymph node involvement
Which type of breast cancer is not curable and what are the treatment aim in this condition?
Advanced breast cancer
Tx aims = prolong survival, relieve symptoms and improve QoL
Name a biological therapy you should know of
Trastuzumab
Which group of patients should be offered trastuzumab?
Patients with tumour size T1C and above
With HER2-+ve invasive breast cancer
Should be done in combination with surgery, chemotherapy, or radiotherapy
Should also be considered in patients with smaller tumour size depending on their co-morbidities, prognosis and possible toxicity with concomitant chemotherapy
What should be regularly assessed in patients on trastuzumab?
Cardiac function
Caution should be taken in patients with underlying cardiac disease
Name a endocrine therapy you should know of
Tamoxifen
Aromatase inhibitor e.g., anastrozole
Which group of patients should be offered tamoxifen as an initial adjuvant endocrine therapy?
Men
Premenopausal women with ER +ve invasive breast cancer (1st line)
Also consider suppressing ovarian function with GnRH
Which group of patients should be offered aromatase inhibitors?
Post-menopausal women
Tamoxifen can be offered instead if aromatase inhibitors are not tolerated or contra-indicated
Sources
https://bnf.nice.org.uk/treatment-summaries/breast-cancer/
https://go.drugbank.com/drugs/DB00675 (Tamoxifen)
https://en.wikipedia.org/wiki/Tamoxifen
https://bnf.nice.org.uk/drugs/tamoxifen/#drug-action
What is the pharmacodynamics of tamoxifen?
Selective (o)estrogen receptor modulator (SERM)
Inhibits growth and promotes apoptosis in oestrogen receptor positive tumours
Also induces GnRH release by occupying oestrogen receptors in the hypothalamus
Does not affect receptors in the bone
What is the pharmacokinetics of tamoxifen?
Oral bioavailability = ~100%
Protein binding = 98% (mostly serum albumin)
Half-life = 5-7 days
Metabolism = hepatic (via CYP2D6, 1A1, 1A2, 3A4, 1B1, 2C9, 2C19, 3A5)
Excretion = 75% faeces
Has a narrow therapeutic index
What are the contraindications of tamoxifen?
Tx of infertility contra-indicated if:
- personal or FHx of idiopathic thromboembolism
- genetic predisposition to thromboembolism
What are the common/very common side effects of tamoxifen?
Alopecia
Anaemia
Cataract, retinopathy
Cerebral ischaemia
GI symptoms - constipation, vomiting, diarrhoea
Embolism and thrombosis (increased risk esp. during and immediately after major surgery or periods of immobility)
Fluid retention
What are the uncommon side effects of tamoxifen?
Hypercalcaemia
Interstitial pneumonitis
Leucopenia
Pancreatitis
Thrombocytopenia
Vision disorders
