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patients) or 50Gy/25fx with simultaneous integrated boost
of 60Gy/30fx (node-positive patients). Pulsed dose rate
MRI-guided adaptive brachytherapy was given in addition.
Follow-up MRI was performed routinely at 3 and 12 months
after end of treatment or at clinical indication. PIF was
defined as a fracture line with or without sclerotic changes
in the pelvic bones. D
50%
, and V
55 Gy
were calculated for os
sacrum and jointly for os ileum and pubis. Patient and
treatment related factors including dose were analysed
for correlation with PIF.
Results
Median follow-up was 25 months. Median age was 50 years.
Twenty patients (20%) were diagnosed with a median of 2
(range 1-3) PIFs; half were asymptomatic. The majority of
the fractures were located in the sacrum (74%). Age was a
significant risk factor (p<0.001), and the incidence of PIF
was 4% and 37% in patients below and above 50 years,
respectively. Sacrum D
50%
was a significant risk factor in
patients >50 years (p=0.04), whereas V
55Gy
of sacrum or
pelvic bone were insignificant (p=0.33 and 0.18
respectively). Risk factors are reported in table 1. A dose-
response curve for D
50%
sacrum in patients >50 years
showed that reduction of sacrum D
50%
of from 40 Gy
EQD2
to
35 Gy
EQD2
reduces PIF from 45% to 22% (Figure 1).
Conclusion
PIF is common after treatment for LACC and is mainly seen
in patients > 50 years. Our data indicates that PIFs are not
related to lymph node boosts, but to dose and volume
associated with irradiation of the elective pelvic target.
Reducing prescribed elective dose from 50 to 45 Gy may
reduce the risk of PIF considerably.
PO-0712 Benefit of semi-extended field radiotherapy
in patients with locally advanced cervical cancer
J. Lee
1
, Y.J. Chen
1
, M.H. Wu
1
, C.L. Chang
2
, T.C. Chen
2
,
J.R. Chen
2
, Y.C. Yang
2
1
MacKay Memorial Hospital, Radiation Oncology, Taipei,
Taiwan
2
MacKay Memorial Hospital, Department of Obstetrics
and Gynecology, Taipei, Taiwan
Purpose or Objective
Patients with locally advanced cervical cancer (LACC) are
at risk for para-aortic lymph node (PALN) metastasis. The
current treatment is pelvic concurrent chemoradiotherapy
(CCRT) with reported PALN failure rate of 9% by RTOG 90-
01, suggesting that pelvic CCRT might not completely
eliminate all microscopic tumours in the PALNs. The
pattern of lymphatic spread from the pelvis to the PALN
appears orderly. This study aimed to evaluate the role of
prophylactic lower PALN irradiation in the era of intensity-
modulated radiotherapy (IMRT).
Material and Methods
We retrospectively assessed 186 patients with stage IB2–
IVA cervical cancer and clinically negative PALNs receiving
definitive IMRT and concurrent weekly cisplatin (40
mg/m2) during 2004–2013. The standard radiation field
was the whole pelvis with a prescribed dose of 50.4 Gy in
28 fractions. Brachytherapy was performed at a dose of 30
Gy in six fractions. The decision to use semi-extended field
radiotherapy (SEFRT) or extended field radiotherapy was
according to physicians’ discretion. Patients receiving
extended field radiotherapy were excluded. The region
targeted by SEFRT included the PALNs below the level of
the renal vessels. The acute and late toxicities were
scored according to the Common Terminology Criteria for
Adverse Events, v3.0. Survival outcomes were calculated
using the Kaplan-Meier method. Multivariate analyses
were performed with Cox regression models. A p-value <
0.05 was considered statistically significant.
Results
One-hundred-ten and 76 patients received pelvic IMRT and
SEFRT, respectively. The patient and tumour
characteristics were not significantly different between
the two groups. All patients completed the planned
radiotherapy, and brachytherapy. The median follow-up
time was 58 months (range, 5–124). The failure patterns
are shown in Table 1. The 5-year overall survival, disease-
free survival, and PALN failure-free survival for SEFRT vs.
pelvic IMRT were 85% vs. 74% (p = 0.06), 84% vs. 73% (p =
0.08), and 98% vs. 90% (p = 0.01), respectively. In the
subgroup analysis, the 5-year overall survival for SEFRT vs.
pelvic IMRT was 81% vs. 59% (p = 0.04) and 87% vs. 82% (p
= 0.48) in patients with positive and negative pelvic lymph
nodes, respectively (Fig. 1). In the multivariable analysis,
SEFRT affected the overall survival (hazard ratio, 0.39;
95% confidence interval, 0.19–0.82; p = 0.01). No patients
had severe late genitourinary toxicities, and three and two
patients had late grade 3 gastrointestinal toxicities in the
SEFRT and pelvic IMRT groups, respectively (p = 0.4).