Hypofractionated boost to the dominant tumor region with intensity modulated stereotactic radiotherapy for prostate cancer: a sequential dose escalation pilot study.
OBJECTIVE
To evaluate the feasibility, tolerability, and preliminary outcomes in patients with prostate cancer treated according to a hypofractionated dose escalation protocol to boost the dominant tumor-bearing region of the prostate.


METHODS
After conventional fractionated external radiotherapy to 64 to 64.4 Gy, 50 patients with nonmetastatic prostate cancer were treated with an intensity-modulated radiotherapy hypofractionated boost under stereotactic conditions to a reduced prostate volume to the dominant tumor region. A rectal balloon inflated with 60 cc of air was used for internal organ immobilization. Five, 8, and 8 patients were sequentially treated with two fractions of 5, 6, or 7 Gy, respectively (normalized total dose in 2 Gy/fraction [NTD(2 Gy)] < 100 Gy, low-dose group), whereas 29 patients received two fractions of 8 Gy each (NTD(2 Gy) > 100 Gy, high-dose group). Androgen deprivation was given to 33 patients. Acute and late toxicities were assessed according to the Radiation Therapy Oncology Group/European Organisation for Research and Treatment of Cancer (RTOG/EORTC) scoring system.


RESULTS
Two patients presented with Grade 3 acute urinary toxicity. The 5-year probabilities of >or=Grade 2 late urinary and late low gastrointestinal (GI) toxicity-free survival were 82.2% +/- 7.4% and 72.2% +/- 7.6%, respectively. The incidence and severity of acute or late toxicities were not correlated with low- vs. high-dose groups, pelvic irradiation, age, or treatment with or without androgen deprivation. The 5-year biochemical disease-free survival (b-DFS) and disease-specific survival were 98% +/- 1.9% and 100%, respectively.


CONCLUSIONS
Intensity-modulated radiotherapy hypofractionated boost dose escalation under stereotactic conditions was feasible, and showed excellent outcomes with acceptable long-term toxicity. This approach may well be considered an alternative to high-dose-rate brachytherapy.
Miralbell
Raymond
R
Servei de Radio-oncologia, Institut Oncòlogic Teknon, Barcelona, Spain. Raymond.Miralbell@hcuge.ch
Mollà
Meritxell
M
Rouzaud
Michel
M
Hidalgo
Alberto
A
Toscas
José Ignacio
JI
Lozano
Joan
J
Sanz
Sergi
S
Ares
Carmen
C
Jorcano
Sandra
S
Linero
Dolors
D
Escudé
Lluís
L
D000368:Aged; D000726:Androgen Antagonists / Q000627:therapeutic use; D005240:Feasibility Studies; D041981:Gastrointestinal Tract / Q000528:radiation effects; D006801:Humans; D007103:Immobilization / Q000295:instrumentation / Q000379:methods; D008297:Male; D010865:Pilot Projects; D011467:Prostate; D011471:Prostatic Neoplasms / Q000188:drug therapy / Q000473:pathology / Q000532:radiotherapy*; D011832:Radiation Injuries / Q000473:pathology; D011836:Radiation Tolerance; D011879:Radiotherapy Dosage; D050397:Radiotherapy, Intensity-Modulated / Q000009:adverse effects / Q000379:methods*; D047368:Tumor Burden; D001743:Urinary Bladder / Q000528:radiation effects
D000726:Androgen Antagonists