[Relation between overall treatment time and local control of early glottic laryngeal cancer: comparison of six versus five times per week].
OBJECTIVE
Local control probabilities of early glottic cancer were evaluated in relation to overall treatment time.


METHODS
From 1971 to 1996, 162 patients with T1 or T2 glottic cancer were treated with radiation therapy. Fifty-nine patients received irradiation six times per week from 1971 to 1987, and 103 patients received irradiation five times per week from 1987 to 1996. Local control rates were calculated by the Kaplan-Meier method, and the log-rank test was used for statistical analysis. The Cox proportional hazards model was used to evaluate the significance of prognostic variables on local control.


RESULTS
The 5-year local control rates were 91.8% for T1 tumors and 78.1% for T2 tumors. There was a statistically significant difference in local control rates between the two groups (p = 0.009). The overall local control rate was 86.4% for both groups, showing no statistically significant difference. Multivariate analysis showed that T stage and overall treatment time were important parameters in relation to local control.


CONCLUSIONS
In early glottic cancer, there is no significant difference in local control probabilities between irradiation six times per week and five times per week.
Department of Radiology, Kitasato University School of Medicine.
Masashi
M
Kitano
Iku
I
Nishiguchi
Yuki
Y
Aoki
Meijinn
M
Nakayama
Hiromi
H
Nagai
Hiroomi
H
Takahashi
Makito
M
Okamoto
Takashi
T
Matsubayashi
Kazushige
K
Hayakawa
D002294:Carcinoma, Squamous Cell / Q000473:pathology / Q000532:radiotherapy*; D005260:Female; D005931:Glottis; D006801:Humans; D007822:Laryngeal Neoplasms / Q000473:pathology / Q000532:radiotherapy*; D008297:Male; D011879:Radiotherapy Dosage; D020266:Radiotherapy, Conformal; D012189:Retrospective Studies; D013997:Time Factors