Treatment/Prognosis

Question 1

What is the preferred initial Tx for pts with OPGs?

Answer 1

OPG Tx (controversial): Initial management most commonly is observation. Tx is typically reserved for pts with documented progression or declining visual acuity.

Question 2

What is the Tx paradigm once pt progresses?

Answer 2

1. Chemo: 1st step d/t risks of local therapy, especially if pt <10 yo
2. RT: good tumor control option for older pts (>10 yo)
3. Debulking Sg: reserved for refractory or symptomatic

Question 3

What chemo agents are generally used for OPG?

Answer 3

Carboplatin + vincristine or cisplatin + etoposide

Question 4

What data support prolonged chemo as a way of avoiding/delaying RT without compromising OS or visual function?

Answer 4

Laithier V et al. prospectively evaluated prolonged chemo (alternating procarbazine/carboplatin, etoposide/cisplatin, and vincristine/cyclophosphamide q3wks). 2nd-line chemo was given at relapse before RT. The objective response rate was 42%, 5-yr OS was 89%, and 5-yr freedom from RT was 61%. (JCO 2003)

Question 5

What data support initial RT instead of initial chemo?

Answer 5

Awdeh RM et al. from St. Jude’s prospectively followed 20 pts. (IJROBP 2012) Visual acuity was better in pts treated with upfront RT compared to those treated with chemo and RT as salvage therapy.

Question 6

What were the findings of the Children’s Oncology Group (COG) protocol (A9952)?

Answer 6

COG A9952 compared chemo regimens (carboplatin/vincristine vs. thioguanine/procarbazine/lomustine/vincristine) for unresectable low-grade glioma and found no statistical difference in 5-year EFS (39% for CV, 52% for TPCV, p = 0.10). (JCO 2012)

Question 7

When is RT indicated in OPG?

Answer 7

RT is typically used after chemo options are exhausted, when there are progressive Sx, or when there is intracranial extension.

Question 8

OPGs are typically treated using what RT dose, fractionation, and technique?

Answer 8

OPGs are typically treated to 45–54 Gy in 1.8 Gy/fx. Proton therapy may have dosimetric advantages, especially in children. Fractionated stereotactically guided RT has good outcomes (5-yr PFS 72%). (Combs SE et al., IJROBP 2005)

Question 9

What is the estimated 5-yr OS in OPG?

Answer 9

The estimated 5-yr OS is 89%. (Laithier V et al., JCO 2003)