Treatment/Prognosis

Question 1

What are the Tx paradigms of choice for the management of pituitary adenomas?

Answer 1

Can consider external RT alone for definitive local Tx with either stereotactic radiosurgery or FSR.

Observation if small, nonsecreting microadenomas or prolactinomas
Medical management with bromocriptine or cabergoline for a microadenoma prolactinoma not causing local Sx. However, 30% cannot tolerate bromocriptine d/t nausea, HA, and fatigue.
Surgical resection if hypersecreting or symptomatic (d/t mass effect for nonsecreting tumors) → observation or postop RT if fail to suppress biochemically.

Question 2

How long does it take for normalization of the PL level to occur after initiating Tx?

Answer 2

Normalization of the PL level takes 1–2 mos following the initiation of pharmacologic suppression as compared to 2–5 yrs after radiotherapy.

Question 3

What pharmacologic agents are used for GH-secreting pituitary adenomas?

Answer 3

Somatostatin, octreotide, and pegvisomant (GH receptor antagonist)

Question 4

What pharmacologic agents are used for ACTH-secreting pituitary adenomas?

Answer 4

Ketoconazole (best), cyproheptadine (inhibits ACTH secretion), mitotane (↓ cortisol synthesis), RU-486 (blocks glucocorticoid receptor), and metyrapone

Question 5

What is the hormone normalization rate after Sg for a hyperfunctioning pituitary tumor?

Answer 5

Hormone levels normalize in 80%–90% of those with microadenoma and ∼65% of those with macroadenoma.

Question 6

What types of surgical resection are used for pituitary tumors, and what are the indications?

Answer 6

Transsphenoidal microsurgery: for microadenomas, decompression, debulking of large tumors, reducing hyperfunctioning tumors

Frontal craniotomy: for large tumors with invasion into cavernous sinus, frontal/temporal lobes

Question 7

What are the LC rates after transsphenoidal resection? Are they better for macroadenomas or microadenomas?

Answer 7

95%. LC rates are better for microadenomas after surgical resection.

Question 8

What are some poor prognostic factors after transsphenoidal resection of prolactinoma?

Answer 8

Size >2 cm, high preop PL level, ↑ age, and longer duration of amenorrhea

Question 9

What are some poor prognostic factors after surgical resection of GH-secreting tumors?

Answer 9

High preop GH and somatomedin-C levels, tumors >1 cm, and extrasellar extension

Question 10

Which pituitary tumors have a high recurrence rate after resection?

Answer 10

TSH-secreting tumors (risk factors: Hx of thyroid ablation, Hashimoto thyroiditis, prior RT/Sg)

Question 11

What are the indications for radiotherapy in the Tx of pituitary tumors?

Answer 11

Pituitary tumor indications for radiotherapy:

Medically inoperable or otherwise not felt to be good surgical candidate d/t proximity to vessels or cavernous sinus.
Persistence of hormone defect after Sg
Macroadenoma with STR or decompression
Recurrent tumor after Sg

Question 12

What are the long-term control rates for hormone-secreting tumors after RT?

Answer 12

Best outcomes with RT for GH-secreting tumors (80%) > ACTH (50%–80%) > PL (30%–40%)

Question 13

What should be done with medical/pharmacologic Tx before initiating RT for pituitary adenomas?

Answer 13

Medical Tx needs to be D/C b/c of lower RT sensitivity with concurrent medical Tx. (Landolt AM et al., J Clin Endocrinol Metab 2000)

Question 14

What is the typical LC rate with RT for pituitary tumors?

Answer 14

The LC after RT is >90% for most pituitary tumors. (Loeffler JS et al., J Clin Endocrinol Metab 2011)

Question 15

What are the typical RT volumes and doses used for pituitary tumors?

Answer 15

With IMRT or proton beam therapy: Treat operative bed + gross Dz + 0.3–0.5 cm PTV; 45–50.4 Gy in 1.8 Gy/fx if postop with no gross Dz, 54 Gy for gross Dz.

Question 16

What evidence supports at least 45 Gy as the min effective RT dose for pituitary tumor control?

Answer 16

Older Florida data (McCollough WM et al., IJROBP 1991): 10-yr LC was 95%.

Question 17

What are the indications for and the benefits of SRS in the Tx of pituitary adenomas?

Answer 17

SRS is used for microadenomas and yields better control of hormone secretion (same LC as fractionated and is more convenient).

Question 18

What are the typical SRS doses used for functional vs. nonfunctional tumors?

Answer 18

Functional SRS dose: ∼20 Gy

Nonfunctional SRS dose: ∼14–18 Gy

Question 19

What are the differences b/t LINAC-based and GK-based SRS for pituitary tumors?

Answer 19

With GK, there is less homogeneous dose to the tumor, more precise setup, and slightly less normal tissue treated (similar outcomes/conformality can be achieved with LINAC-based SRS, however).

Question 20

When is FSR preferred instead of SRS for pituitary adenomas?

Answer 20

FSR is preferred when the pituitary lesion is >3 cm and/or the lesion is <3 mm from the chiasm.

Question 21

What RT doses are used with fractionated EBRT?

Answer 21

45–50 Gy (nonfunctioning), 50–54 Gy (functioning).

Question 22

What form of RT can be used to reduce dose to normal tissues with fractionated EBRT?

Answer 22

Proton therapy. The Loma Linda experience showed it to be effective. (Ronson BB et al., IJROBP 2006) However, long-term results needed to determine clinical results from normal tissue sparing.