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ESTRO 36 2017
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Conclusion
For patients with positive pelvic lymph nodes LACC,
prophylactic PALN irradiation up to the level of renal
vessels could reduce PALN recurrence and improve
outcomes with few severe late toxicities. A prospective
study investigating the risk stratification based optimal
radiation field in patients with LACC is warranted.
PO-0713 Diffusion-weighted MRI for predicting
prognosis after radiotherapy in stage IIIB cervical cancer
Y. Watanabe
1
, N. Ii
1
, T. Kawamura
1
, Y. Toyomasu
1
, T.
Takada
1
, H. Tanaka
1
, E. Kondo
2
, T. Tabata
2
, H. Sakuma
3
,
Y. Nomoto
4
1
Mie University Hospital, radiation oncology, Tsu, Japan
2
Mie University Hospital, Obstetrics and Gynecology,
Tsu, Japan
3
Mie University Graduate School of Medicine, radiology,
Tsu, Japan
4
Mie University Graduate School of Medicine, radiation
oncology, Tsu, Japan
Purpose or Objective
To investigate the value of the apparent diffusion
coefficient (ADC) on pre- and mid-treatment MRI in
predicting the prognosis (local recurrence/metastasis) of
stage IIIB uterine cervical cancer patients who receive
concurrent chemoradiotherapy (CCRT).
Material and Methods
Twenty-three patients with stage IIIB cervical cancer (the
International Federation of Gynecology and Obstetrics,
FIGO) underwent 1.5T MRI, including T2 weighted imaging
(T2WI) and diffusion-weighted imaging at a b-value of 0
and 1,000 (s/mm
2
) before and 3 weeks after the initiation
of treatment. Twenty-two of the 23 patients received
standard CCRT (chemotherapy including weekly cisplatin
and concurrent radiotherapy including external body
radiation therapy and brachytherapy). When measuring
the ADCs, the regions of interest (ROIs) were manually
drawn to include as much of the tumor as possible in two
slices; the two mean values were recorded and averaged.
The pre ADCs and mid ADCs were defined as the ADCs
measured on pre- and mid-treatment MRI, respectively.
The ΔADC values were obtained by subtracting the pre-
ADC from the mid- ADC, and the %ADC values were
determined by dividing the ΔADC values by the pre-ADC
values. The sizes of the tumors were also measured on pre-
and mid-treatment T2WI. The %size was defined as the
rate of decrease in the longest diameter of the tumor.
These parameters were statistically analyzed in relation
to the prognosis (local recurrence/metastasis) of the
patients. The statistical analyses included the Mann-
Whitney U test, Fisher’s exact test, and a receiver
operating characteristics (ROC) analysis.
Results
In the study population (n=23), local recurrence or
metastasis (R/M) was found during follow-up (12-64
months, median: 40 months) in 7 patients (30%); 2 of these
patients had local recurrence, 4 had metastasis and 1 had
both. The ΔADC values of the patients with and without
R/M were 0.210 ± 0.070 and 0.331 ± 0.126, respectively,
which amounted to a statistically significant difference
(p=0.013). The %ADC values of the patients with R/M were
significantly lower (mean ± SD: 23.5 ± 8.25) in comparison
to the patients without R/M (37.9 ± 16.4) (p=0.012). The
area under the ROC curve of the %ADC was 0.835, and the
sensitivity and specificity were 87.5% and 85.7%,
respectively, when using an optimal cutoff value of 25.7.
The proportion of patients who had %ADC values of <30%
was significantly greater among the patients with R/M
(6/7, 86%) than it was among those without R/M (4/16,
25%) (p=0.019). The %size values of the two groups did not
differ to a statistically significant extent (p= 0.483).
Conclusion