Question

Which is the treatment of choice for irradiation in chordoma?

• A. Protons
• B. Electrons
• C. Gamma radiation
• D. 3D-CRT

Hint:

Think Bragg peak - a beam that stops after hitting the deep target.

Answer 1

The Correct Option is A

Step 1: Chordoma is a rare, slow-growing malignant tumour arising from notochordal remnants, typically at the clivus (skull base) and the sacrum. It is relatively radioresistant, so very high tumour doses are needed for control.
Step 2: Because chordomas sit close to critical structures (brainstem, spinal cord, sacral nerves), the radiation must deposit a high dose in the tumour while sparing adjacent tissue.
Step 3: Proton therapy uses the Bragg peak - protons deposit most energy at a defined depth and almost nothing beyond it. This permits high precision, high tumour dose, and minimal exit dose to vital structures, making it the modality of choice. Carbon-ion therapy is a related particle option.
Step 4: Electrons (b) penetrate poorly and suit superficial lesions; gamma radiation (c) and 3D-CRT (d) are conventional photon techniques that cannot match the conformality and sparing of protons for these deep, radioresistant tumours. Hence the answer is (a) Protons.