[Chordomas of the base of the skull and upper cervical spine. 100 patients irradiated by a 3D conformal technique combining photon and proton beams].
OBJECTIVE
To define prognostic factors for local control and survival in 100 consecutive patients treated by fractionated photon and proton radiation for chordoma of the skull base and upper cervical spine.


METHODS
Between December 1995 and August 2002, 100 patients (median age: 53 years, range: 8-85, M/F sex-ratio: 3/2), were treated by a combination of high-energy photons and protons. The proton component was delivered by the 201 MeV proton beam of the Centre de Protonthérapie d'Orsay (CPO). The median total dose delivered to the gross tumour volume was 67 Cobalt Gray Equivalent (CGE) (range: 60-71). A complete surgery, incomplete surgery or a biopsy was performed before the radiotherapy in 16, 75 and 9 cases, respectively.


RESULTS
With a median follow-up of 31 months (range: 1-87), 25 tumours failed locally. The 2 and 4-year local control rates were 86.3% (+/-3.9%) and 53.8% (+/-7.5%), respectively. According to multivariate analysis, less than 95% of the tumour volume encompassed by the 95% isodose line (P=0.048; RR: 3.4 IC95% [1.01-11.8]) and a minimal dose less than 56 CGE (p=0.042; RR: 2.3 IC95% [1.03-5.2]) were independent prognostic factors of local control. Ten patients died. The 2 and 5-year overall survival rates were 94.3% (+/-2.5%) and 80.5% (+/-7.2%). According to multivariate analysis, a controlled tumour (P=0.005; RR: 21 IC95% [2.2-200]) was the lonely independent favourable prognostic factor for overall survival.


CONCLUSIONS
In chordomas of the skull base and upper cervical spine treated by surgical resection followed by high-dose photon and proton irradiation, local control is mainly dependent on the quality of radiation, especially dose-uniformity within the gross tumour volume. Special attention must be paid to minimise underdosed areas due to the close proximity of critical structures and possibly escalate dose-constraints to tumour targets in future studies, in view of the low toxicity observed to date.
Noël
G
G
Centre de protonthérapie d'Orsay, institut Curie, CPO bâtiment 101, campus universitaire, 91898 Orsay cedex, France. noel@ipno.in2p3.fr
Feuvret
L
L
Dhermain
F
F
Mammar
H
H
Haie-Méder
C
C
Ponvert
D
D
Hasboun
D
D
Ferrand
R
R
Nauraye
C
C
Boisserie
G
G
Beaudré
A
A
Gaboriaud
G
G
Mazal
A
A
Touboul
E
E
Habrand
J-L
JL
Mazeron
J-J
JJ
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002817:Chordoma / Q000473:pathology / Q000532:radiotherapy*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017785:Photons / Q000627:therapeutic use; D011379:Prognosis; D061766:Proton Therapy; D011874:Radiometry; D019292:Skull Base Neoplasms / Q000473:pathology / Q000532:radiotherapy*; D013125:Spinal Neoplasms / Q000473:pathology / Q000532:radiotherapy*; D016896:Treatment Outcome; D011522:Protons
D011522:Protons