Radiation Treatment Technique for Early Stage Glottic

Question 1

RT dose for T1 larynx cancer?

Answer 1

63 Gy in 28 fx (2.25 Gy/fx)

Question 2

RT dose for T2 larynx cancer?

Answer 2

70 Gy in 35 fx or 65.25 Gy in 2.25 Gy/fx

Or consider hyperfractionation with 79 Gy at 1.2 Gy bid or mild acceleration

Question 3

What are the factors the influence local control especially for T2 larynx cancer?

Answer 3

1. Fraction size 2.25 Gy > 2 Gy&raquo_space; 1.8 Gy
2. Overall treatment time < 43 days
3. Altered fractionation increases local control ~ 10% in T2N0 disease

Question 4

What should be the target volume for T1 larynx cancer?

Answer 4

Entire glottic larynx, anteriorly flash 1 cm, posteriorly cover to anterior edge of vertebral bodies, superiorly cover to top of thyroid cartilage, and inferiorly cover the bottom of cricoid cartilage

Question 5

What is the target volume for T2 larynx cancer?

Answer 5

Same as T1 with adjustments superiorly and/or inferiorly if T2 based on supraglottic or subglottic extension.

Question 6

What is the typical field border with conventional techniques for T1 or T2 larynx cancer?

Answer 6

Conventional techniques field border 2 cm above or below GTV

Question 7

What is the RT techniques used for T1 or T2 larynx cancer?

Answer 7

3DCRT (right and left opposed laterals, can consider 3 beam, 0, 70, and 290 degrees)

Question 8

In which situation should you consider IMRT for T1 or T2 larynx cancer?

Answer 8

For carotid artery sparing

Question 9

Explain the simulation technique for larynx cancer.

Answer 9

• Supine w/ neck hyperextended, aquaplast mask covering the head and shoulders, isocenter in midlarynx.
• Pull straps for shoulder retraction.
• Consider thin bolus for patients with anterior disease.
• Patient should be reminded not to swallow during simulation or treatment as this can cause distortion of anatomy.