Follow-up/Toxicity

Question 1

What are the RTOG 0225 dose constraints for the chiasm/optic nerves when using IMRT for NPC?

Answer 1

Per RTOG 0225, the dose constraints for the chiasm/optic nerves are 54 Gy or 1% of the PTV not >60 Gy.

Question 2

What are the accepted RTOG 0225 dose constraints for the parotids?

Answer 2

Per RTOG 0225, the dose constraints for the parotids are as follows: mean dose <26 Gy (should be achieved in at least 1 gland) or at least 20 cc of the combined volume of both parotid glands <20 Gy or at least 50% of 1 gland <30 Gy.

Question 3

Why might sparing of the parotid glands not be sufficient to prevent xerostomia?

Answer 3

Sparing of the parotids alone may not be sufficient b/c mucus production by minor salivary glands may be necessary for subjective improvement, according to data from Prince of Wales Hospital (Kam MK et al., JCO 2007): 60 pts randomized to IMRT or 2D-RT. Objective improvement in both stimulated and unstimulated salivary flow was found, but not in the subjective improvement of xerostomia.

Question 4

What is the NCCN-recommended f/u schedule for NPC pts?

Answer 4

H&P with nasopharyngolaryngoscopy (q1–3 mos for yr 1, q2–6 mos for yr 2, q4–8 mos for yrs 3–5, and q12 mos if >5 yrs), imaging (for signs/Sx or smoking Hx/surveillance), TSH q6–12 mos (if neck irradiated), speech/hearing/dental evaluation, and smoking cessation