Mock 33 Radiotherapy

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Stem
Case of proximal femur fractur known case of hypothyroidism and history of breast cancer and mastectomy 5 years ago.
You will be given paper with lab results showing
Increase urea, creatinine & hypercalcemia.

Possible causes of hypercalcemia?

Local bone metastases
Chronic kidney disease

What to look for in bone scan?

Areas of increased metabolic activity (hot spots), i.e. any increase in uptake by cells

Why will you do THR or hemiarthroplasty not fixation by nail or plate?

Will depend on site of proximal femoral fracture, if intracapsular then THR or hip hemiarthroplasty
Because of metastasis and hypothyroidism, there is a high risk of nonunion and failure to fixation

Why will you send the femoral head to histopathology?

To rule out the tumour / metastasis
Identify the cause of pathological fracture

What is the mechanism of action of radiotherapy?

Diminish osteoclasts activation and kill tumour cell by damaging the DNA of the cell by two mechanisms
Direct action: directly damage DNA causing cellular death
Indirect action: formation of free radicals which causes cell death.

Why to use radiotherapy other than killing cancer cells? i.e. what is the function of radiotherapy apart from killing cancer cells?

Reduction of tumour volume before surgery
Relief of pain
After resection to kill any cells that might escape
Used in low dose radiation in X-ray

Give 3 causes of PE and DVT in this patient after THR?

Hypercoagulative state due to cancer
Postoperative immobility
Venous stasis during surgery

Two medications for breast cancer

Hormonal therapy like Aromatase inhibitors (anastrozole) and tamoxifen
Herceptin

Herceptin mechanism of action, how it works?

Monoclonal antibody
Causes antibody-mediated destruction of cells overproducing HER2.

What is the regimen of Herceptin?

Weekly for 12 months.

Why aromatase inhibitors not given in for premenopausal women?

High level of E2 production by the ovaries which makes suppression ineffective.
High levels of androgens competing with aromatase inhibitors for the aromatase enzyme.

Define mammary Paget cell

MG epithelial cells derived from underlying ductal adenocarcinoma & can invade into skin of nipple and areola

Mechanism of action of aromatase inhibitor

By inhibition of aromatase enzyme which convert androgen to oestrogen

Modern clinical practice for Trastuzumab (Herceptin) in the adjuvant setting typically involves once-weekly or once-every-three-weeks infusions.