Effect of dose rate on local control and complications in definitive irradiation of T1-2 squamous cell carcinomas of mobile tongue and floor of mouth with interstitial iridium-192.
From 1971 to 1988, 134 T1 and 145 T2 biopsy-proven squamous cell carcinomas of mobile tongue and floor of mouth were definitively managed by iridium-192. Implantations were performed using either guide gutters or afterloading plastic catheters. The prescribed dose at the reference isodose (85% of the basal dose rate, Paris system) was 60-70 Gy. Total dose was not adjusted to dose rate or tumor volume. Results of the 279 implants have been analysed to look for a possible influence of dose rate on local control and necrosis. Follow-up patients free of local recurrence is 1-180 months with average of 51 months. The 279 tumors were divided in four groups according to dose and dose rate: greater than or equal to 62.5 Gy and greater than or equal to 0.5 Gy/h (n = 130), greater than or equal to 62.5 Gy and less than 0.5 Gy/h (n = 36), less than 62.5 Gy and greater than or equal to 0.5 Gy/h (n = 81), less than 62.5 Gy and less than 0.5 Gy/h (n = 32). The four groups were comparable according to age, sex, tumor diameter and macroscopic aspect. At 5 years, the estimated local control (Kaplan Meier) was 93, 87, 79 and 52%, respectively (dose adjusted to dose rate: p less than 0.001, dose rate adjusted to dose: p less than 0.01, Log-rank); the necrosis rate was 44, 24, 37 and 5%, respectively (dose adjusted to dose rate: p = 0.08, dose rate adjusted to dose: p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)
Mazeron
J J
JJ
Département de Cancérologie, Hôpital Henri Mondor, Créteil, France.
Simon
J M
JM
Le Péchoux
C
C
Crook
J M
JM
Grimard
L
L
Piedbois
P
P
Le Bourgeois
J P
JP
Pierquin
B
B
D002294:Carcinoma, Squamous Cell / Q000473:pathology / Q000532:radiotherapy*; D004307:Dose-Response Relationship, Radiation; D006801:Humans; D007496:Iridium Radioisotopes / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*; D009060:Mouth Floor / Q000473:pathology / Q000528:radiation effects; D009062:Mouth Neoplasms / Q000473:pathology / Q000532:radiotherapy*; D015999:Multivariate Analysis; D009336:Necrosis / Q000209:etiology / Q000473:pathology; D011832:Radiation Injuries; D011879:Radiotherapy Dosage; D014062:Tongue Neoplasms / Q000473:pathology / Q000532:radiotherapy*
D007496:Iridium Radioisotopes