Transcript Cesium-131 brachytherapy in patients with primary and

Permanent Interstitial Implants
Ideal strategy to curatively manage small volume
gynecologic malignancies
Can deliver high cumulative radiation dose to tightly
conformal volumes.
Reduces toxicity compared to external RT.
Use currently limited due to lack of familiarity/experience
with this modality
Revival of interest in interstitial implants with supporting
clinical data and development of safer, low energy sources
with better decay characteristics (half-life, energy, dose
rate)
Brabham JG, Cardenes HR. Am J Clin Oncol 2009; 32:417422.
N=19
N=19
Results
Median age: 76 years (range, 38–87)
Median tumor volume: 3.3 cm3 (range, 0.8 –21.3)
Median previous radiation dose: 67 Gy (range, 38.7–
91.6)
Median prescribed dose: 50 Gy (range, 25–55)
Median follow-up: 21 months
CR rate 94.7%
LC rate 63.1% (ultimately achieved in 78.9%)
52.6% of patients were alive with no evidence of disease
One grade 3 toxicity (5.3%)
Brabham JG, Cardenes HR. Am J Clin Oncol 2009; 32:417-422.
Conclusions regarding IRI using Au198
198Au-IRI
is a safe, cost-effective, and reasonably
efficacious method for controlling locally recurrent,
low-volume, well-selected gynecologic malignancies,
and treated with previous full-dose radiotherapy. It
represents a reasonable potential therapeutic option
in the salvage setting in patients who meet these
criteria, particularly in women who are not
candidates for or are unwilling to undergo radical
salvage surgery.
Brabham JG, Cardenes HR. Am J Clin Oncol 2009; 32:417-422.
UK Experience with Permanent Isotopes
in Gynecologic Cancers
30 year experience with permanent Au198,
particularly in gynecologic cancers (Randall)
No known experience to evaluate the safety/efficacy
of Cs131 in gynecologic malignancies
Hypothesized Cs131 efficacy would be at least
equivalent to Au198 with the added benefit of lower
radiation exposure for occupationally exposed
personnel
Based on 4+ years of experience, UK is exclusively
utilizing Cs131 for permanent interstitial
brachytherapy for gynecologic malignancies
Favorable properties of Cesium-131
Short ½ life translates into high initial dose rate (9.7
days vs. 2.7 days for Au-198)
Lower energy (30.4 KeV vs 400 KeV for Au-198)
translates into adequate dose distribution with better
radiation safety*
Relative equivalence to Au198 facilitating clinical
dosing/conversions
UK Dosimetric Modeling
Ran multiple Monte Carlo simulations to evaluate optimal
distribution of activity (essentially Quimby vs Manchester
rules). Goal was adequate coverage and homogeneity of
dose distribution.
Determined that optimal planning was based on
Paterson-Parker (Manchester) rules for permanent
implants (uneven distribution of activity to create more
homogeneity)
To determine doses, used BED formalism to estimate,
then adopted correction factor (compared to Au198) based
on clinical experience = 1.1
Luo W, Molloy J, Aryal P, Feddock J, Randall M. Med Phys., 41 (2): 024101 (2014
).
University of Kentucky
Experience with Cs-131
Recently published results of initial 14 patients
treated with a total of 17 Cs-131 implants
Included spectrum of gynecologic sites and
pathologies for primary and recurrent cancers
Seven implants performed as a boost
Wooten CE, Randall ME, … Feddock J. Implementation and Early Clinical Results utilizing Cs-131
permanent interstitial implants for gynecologic malignancies. Gyn Oncol 2014;
Wooten CE, Randall ME, … Feddock J. Implementation and Early Clinical Results utilizing Cs-131 permanent
interstitial implants for gynecologic malignancies. Gyn Oncol 2014.
Local Control
Actuarial local control at 12 months = 84.4%
Two local failures occurred 5 and 7 months after
the implant
One patient was able to gain local control through
re-implantation
The second received a dose of 44 Gy to largest implant
area of 17.5 cm3
Wooten CE, Randall ME, … Feddock J. Implementation and Early Clinical Results utilizing Cs-131 permanent
interstitial implants for gynecologic malignancies. Gyn Oncol 2014.
Table 2 Radiation dose characteristics of additional Cs-131 implants following initial implant by
patient
Patient Implant Volume
#
#
(cm3)
Indication
Cs-131
Total tumor
Total dose to
Local
dose (Gy) treatment dose treated area (Gy)† control
(Gy)*
Regional
Control
6
2
3.14
Regional vaginal
recurrence
33
33
102.30
No
Yes
6
3
1.77
Partial response to
implant #2
45
78
147.30
Yes
Yes
7
2
3.14
Separate vaginal
recurrence
50
50
93.10
Yes
Yes
* Combined treatment dose to tumor including Cs-131 implant with external beam radiation and
brachytherapy calculated using EQD2
† Cumulative estimated dose to the treated area from contributions of previous radiation therapy and total
tumor treatment dose
Wooten CE, Randall ME, … Feddock J. Implementation and Early Clinical Results utilizing Cs-131 permanent
interstitial implants for gynecologic malignancies. Gyn Oncol 2014.