B. Rau et al., Preoperative radiochemotherapy in locally advanced or recurrent rectal cancer: Regional radiofrequency hyperthermia correlates with clinical parameters, INT J RAD O, 48(2), 2000, pp. 381-391
Citations number
43
Categorie Soggetti
Radiology ,Nuclear Medicine & Imaging","Onconogenesis & Cancer Research
Journal title
INTERNATIONAL JOURNAL OF RADIATION ONCOLOGY BIOLOGY PHYSICS
Purpose: Preoperative radiochemotherapy (RCT) is a widely used means of tre
atment for patients suffering from primary, locally advanced, or recurrent
rectal cancer. We evaluated the efficacy of treatment due to additional app
lication of regional hyperthermia (HRCT) to this conventional therapy regim
e in a Phase II study, employing the annular phased-array system BSD-2000 (
SIGMA-60 applicator), The clinical results of the trial were encouraging. W
e investigated the relationship between a variety of thermal and clinical p
arameters in order to assess the adequacy of thermometry, the effectiveness
of hyperthermia therapy, and its potential contribution to clinical endpoi
nts.
Methods and Materials: A preoperative combination of radiotherapy (1.8 Gy f
or 5 days a week, total dose 45 Gy applied over 5 weeks) and chemotherapy (
low-dose 5-fluorouracil [5-FU] plus leucovorin in the first and fourth week
) was administered to 37 patients with primary rectal cancer (PRC) and 18 p
atients with recurrent rectal cancer (RRC), Regional hyperthermia (RHT) was
applied once a week prior to the daily irradiation fraction of 1.8 Gy. Tem
peratures were registered along rectal catheters using Bowman thermistors,
Measurement points related to the tumor were specified after estimating the
section of the catheter in near contact with the tumor. Three patients wit
h local recurrence after abdominoperineal resection, had their catheters po
sitioned transgluteally under CT guidance, where the section of the cathete
r related to the tumor was estimated from the CT scans. Index temperatures
(especially T-max, T-90) averaged over time, cumulative minutes (cum min) (
here for T-90 > reference temperature 40.5 degrees C), and equivalent minut
es (equ min) (with respect to 43 degrees C) were derived from repetitive te
mperature-position scans (5- to 10-min intervals) utilizing software specia
lly developed for this purpose on a PC platform. Using the statistical soft
ware package SPSS a careful analysis was performed, not only of the varianc
e of thermal parameters with respect to clinical criteria such as toxicity,
response, and survival but also its dependency on tumor characteristics.
Results: The rate of resectability (89%) and response (59%) were high for t
he PRC group, and a clear positive correlation existed between index temper
atures (T-90) and thermal doses-(cum min T-90 greater than or equal to 40.5
degrees C). Even though the overall 5-year survival was encouraging (60%)
and significantly associated with response, there was no statistically sign
ificant relationship between temperature parameters and long-term survival
for this limited number of patients. However, nonresectable tumors with hig
her thermal parameters (especially cum min T-90 greater than or equal to 40
.5 degrees C) had a tendency for better overall survival. We found even hig
her temperatures in patients with recurrences (T-90 = 40.7 degrees C versus
T-90 = 40.2 degrees C). However, these conditions for easier heating did n
ot involve a favorable clinical outcome, since surgical resectability (22%)
and response rate (28%) for the RRC group were low. We did not notice any
other dependency of thermal parameters to a specific tumor or patient chara
cteristics. Finally, neither acute toxicity (hot spots) induced by hyperthe
rmia or RCT nor perioperative morbidity were correlated with temperature-de
rived parameters, Only a higher probability for the occurrence of hot spots
was found during treatment with elevated power levels.
Conclusion: In this study with two subgroups, i.e., patients with PRC (n =
37) and RRC (n = 18), there exists a positive interrelationship between the
rmal parameters (such as T-90, cum min T-90 greater than or equal to 40,5 d
egrees C) and clinical parameters concerning effectiveness. Additional hype
rthermia treatment does not seem to enhance toxicity or subacute morbidity,
Procedures to measure temperatures and to derive thermal parameters, as we
ll as the hyperthermia technique itself appear adequate enough to classify
heat treatments in sessions as more or less effective, However, cautious in
terpretation of these relationships is essential, since we have found that
subgroups (e.g., RRC) achieve higher temperatures due to reasons regarding
the tumor biology or disturbed microcirculation nevertheless indicating an
unfavorable prognosis. (C) 2000 Elsevier Science Inc.