Authors
Patient no
Type of RT
Median dose Gy
Follow-up months
Tumor control (%)
Flickinger et al. [10]
21
CRT
60
7.3 years
95 at 10 years
Regine et al. [12]
58
CRT
56–62
17 years
82 at 10 years
Rajan et al. [11]
173
CRT
50
12 years
83 at 10 years
Hetelekidis et al. [6]
37
CRT
54
49
86 at 10 years
Mark et al. [13]
25
CRT
46–63
8 years
96 at 5 years
Habrand et al. [14]
37
CRT
50
98
56.5 at 10 years
Merchant et al. [15]
15
CRT
54
72
94 at 5 years
Varlotto et al. [16]
24
CRT
60
12 years
89 at 10 years
Stripp et al. [7]
76
CRT
55
7.6 years
84 at 10 years
Moon et al. [17]
50
CRT
54
12.8 years
91 at 10 years
Pemberton et al. [3]
87
CRT
43
8 years
77 at 10 years
Merchant et al. [18]
28
CRT
55
36
90 at 3 years
Masson-Cote et al. [5]
53
CRT
50
86
69 at 10 years
Selch et al. [19]
16
FSRT
50.4
28
75 at 3 years
Schulz-Ertner et al. [20]
26
FSRT
52.2
43
100 at 10 years
Minniti et al. [21]
39
FSRT
50
40
92 at 5 years
Combs et al. [22]
40
FSRT
52.2
98
100 at 10 years
Hashizume et al. [23]
10
FSRT
33
25.5
100
Kanesaka et al. [24]
16
FSRT
30
52
82.4 at 3 years
Harrabi et al. [25]
55
FSRT
52.2
128
92 at 10 years
Fritzek et al. [26]
15
FSRT/PBT
56.9 CGE
13.1 years
85 at 10 years
Luu et al. [27]
16
PBT
50.4–59.4 CGE
60.2
93
The optimal dose of irradiation and timing of RT for patients with craniopharyngiomas is still matter of debate. Although a few reports have shown a better tumor control for doses >55 Gy [10, 13, 16], a comparable 5-year tumor control >90 % has been showed with doses of 50–54 Gy given in daily fractions of 1.7–1.8 Gy [3, 5, 6, 14], suggesting that such doses may achieve a similar tumor control as for higher doses, possibly decreasing the incidence of late radiation-induced toxicity. Another debated issue is the optimal timing of RT after surgical resection of a craniopharyngioma. A few pediatric studies have suggested that RT given immediately after surgery provides better local control than RT given at tumor recurrence [12, 28]. For adult patients, tumor control and survival are apparently similar when RT is administered postoperatively or at recurrence [3, 7, 17]. In clinical practice, early postoperative RT is usually reserved for patients with residual tumor after limited surgery; however, patients with complete resection may continue surveillance without immediate irradiation.
RT for patients with craniopharyngiomas may be associated with long-term toxicity. The most frequent complication is represented by the development of hypopituitarism; a new pituitary deficit or worsening of a partial hypopituitarism has been reported in 20–60 % of irradiated patients after 5–10 years [10–16], and this proportion is likely to increase with longer follow-up. Other toxicities, including radiation optic neuropathy and other cranial deficits, cerebrovascular events [11, 12, 29], and second malignant neoplasms [6, 8, 12, 14] are reported in less than 3–5 % of patients. Although the potential detrimental effect of RT on neurocognitive function especially in young patients is of concern, a few studies, using formal neurocognitive testing, showed no significant neurocognitive decline in patients with craniopharyngioma after radiation therapy [15, 18, 30]. In contrast, other factors such as extensive surgery, hydrocephalus at diagnosis, and shunt insertion have been associated with worse neurocognitive outcome [18, 30].
14.3 Stereotactic Techniques
Stereotactic RT is a further refinement of 3D conformal RT. Improved immobilization is achieved with either a frame-based or a frameless mask stereotactic system with submillimetric accuracy of patient repositioning. Radiation dose can be delivered as single-fraction SRS, as multi-fraction SRS (2–5 fractions), and as FSRT when a conventional fractionation of 1.8–2.0 Gy per fraction is used. SRS can be delivered using a modified linear accelerator (Linac SRS), a Gamma Knife (GK SRS), or a CyberKnife device (CK SRS).
Improved local control in patients with craniopharyngioma undergoing FSRT has been shown in several studies [19–25] (Table 14.1). In a series of 39 patients treated at the Royal Marsden Hospital with FSRT using a dose of 50 Gy in 30 fractions, the 5-year actuarial tumor control and survival rates were 92 % and 100 %, respectively [21]. Similarly, Combs et al. [22] reported 10-year local control and survival rates of 100 % in a series of 40 patients treated with FSRT using doses of 54 Gy in 30 fractions. In another series of 55 patients treated with FSRT, Harrabi et al. [25] showed 10-year local control and OS rates of 92 % and 83 %, respectively, at a median follow-up of 128 months. Overall, the reported results indicate that FSRT is an effective treatment option for craniopharyngiomas of any size. In the respect of the limited follow-up data in most published studies, FSRT is a safe treatment modality, associated with a relatively low toxicity. The main reported late effect of treatment is the development of hypopituitarism, with a new hormonal deficit in up to 40 % of treated patients at 5 years. Other complications are rarely observed, suggesting that the use of stereotactic irradiation could further reduce the toxicity observed with conventional RT.
SRS may represent a convenient treatment option for patients with small tumors not in close proximity (0–3 mm) to the optic pathway. One of the most widely chosen treatment modalities to deliver SRS is the GK [31]. In its most used version, an array of 201 cobalt sources are arranged in a hemisphere and focused using a collimator helmet onto a central point (isocenter). This results in a spherical dose distribution of 4–18 mm diameter. For larger irregularly shaped tumors, the best tumor conformality is achieved by different combinations of number, aperture, and position of the collimators using a multiple isocenter technique. During treatment, the patient is immobilized with a head frame fixed to the outer skull, allowing a positioning accuracy of <1 mm.
Several studies have reported the safety and efficacy of GK SRS in patients with residual or recurrent craniopharyngiomas after surgery [32–38] (Table 14.2). In a study of 98 patients treated with GK SRS, Kobayashi et al. [34] reported a tumor control rate of 79.6 % at a median follow-up of 65 months. In another series of 35 patients with craniopharyngiomas, Saleem et al. [38] observed a local control of 88.5 % at a median follow-up of 22 months, and similar findings have been reported by others [32, 33, 35–37]. Overall, local control rates ranging from 34 to 94 % using median marginal doses of 11–16 Gy are reported in seven studies including 286 patients (Table 14.2).
Table 14.2
Summary of published studies on SRS for craniopharyngioma
Authors | Patient no | Type of SRS | Marginal dose Gy | Follow-up months | Tumor control (%) |
|---|---|---|---|---|---|
Chung et al. [32] | 31 | GK SRS | 12 | 36 | 87 |
Ulfarsson et al. [33] | 21 | GK SRS | 3–25 | 17 years | 34 |
Kobayashi et al. [34] | 98 | GK SRS | 11 | 65 | 79.6 |
Yomo et al. [35] | 18 | GK SRS | 11.6 | 24 | 94 |
Niranjan et al. [36] | 46 | GK SRS | 13 | 62 | 68 at 5 years |
Xu et al. [37] | 37 | GK SRS | 14.5 | 50 | 67 at 5 years |
Saleem et al. [38] | 35 | GK SRS | 11.5
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