Transcript Cesium-131 brachytherapy in patients with primary and

Morbidity / Complications
Patients experienced only expected postimplant reactions
Two patients with self-limited superficial
necrosis of vaginal mucosa
No hospitalizations, fistulas or other severe
side effects
Wooten CE, Randall ME, … Feddock J. Implementation and Early Clinical Results utilizing Cs-131 permanent
interstitial implants for gynecologic malignancies. Gyn Oncol 2014.
WHAT IF THERE WERE A
TREATMENT FOR RECURRENT
GYNECOLOGIC CANCERS WITH:
A SIGNIFICANT SALVAGE RATE (CURE), and
LIMITED MORBIDITY, and
AT A REASONABLY LOW COST?
THERE IS SUCH A TREATMENT FOR SELECTED
PATIENTS: INTERSTITIAL RE-IRRADIATION.
DON’T FORGET ABOUT IT!
Use of Cesium-131 in Definitive Therapy for
Gynecologic Malignancies
Primarily used as a boost:
Adjuvantly for a positive margin (vaginal cuff post hysterectomy)
Definitively to treat gross disease
Unresectable disease
Small volume residual following standard therapy
Ideally reserved for patients considered unsuitable for
treatment using Syed-Neblett either for medical or
logistical reasons
UK Experience using Cs-131 as a
component of primary therapy
N=18
Median age: 66 (37-87)
Type of Cancer
N=
Recurrent Endometrioid AdenoCa
5
Post-operative Endometrioid AdenoCa
4
Post-operative Cervical SCCa
2
Primary Vaginal AdenoCa
3
Vaginal Melanoma
2
Vulvar SCCa
2
Characteristics of Cs-131
Implants used for Primary
Therapy
Total implants performed: 18
Indication for Cesium-131 Boost
N=
Microscopic positive margin
4
Gross disease post-operatively
2
Gross disease at end of primary radiation
10
Gross disease before primary radiation (melanoma)
2
Median dose = 22 Gy (15-50 Gy)
Median seed count = 13 (9-30)
Median source strength = 0.76 u/seed (0.48-1.8)
Median area treated = 6 cm2 (2-19.25 cm2)
Results incorporating Cesium-131
into Initial Therapy
Median Follow-up 6.7 months (1-23.5 months)
Disease control:
There have been no local failures – LC = 100%
Only one patient has developed regional and/or metastatic
disease
Patient with vaginal melanoma developed a confirmed inguinal lymph node
recurrence at 8.2 months post treatment
Toxicity:
Very low – nearly all develop acute grade 1-2 mucosal reactions
that quickly resolve
Two patients have developed grade 3 mucosal reactions
One with persistent changes beyond 6 months
One patient has identified persistent grade 2 GU toxicity beyond
6 months
A Case of Vulvovaginal Melanoma
40 Gy to 5mm using Cs-131
2 weeks later
Additional 30 Gy using EBRT
What can be gained by adding Interstitial
Brachytherapy?
45 Gy PRT followed by ICB 7 Gy to
5mm depth x3
Dose to 5mm Depth
• BED = 88.8 Gy
• EQD23 = 74.0 Gy
Dose to Vaginal Surface
• BED = 104.4 Gy
• EQD23 = 87.0 Gy
Dose to the Rectum (approx 5mm deep)
• EQD210 = 85.2 Gy
– 7 Gy per implant delivered to the entire active
length treated
45 Gy PRT followed by ICB 7 Gy to surface
x2 then 20 Gy Cs-131
Dose to 5mm Depth
• BED = 88.8 Gy
• EQD23 = 73.0 Gy
Dose to Vaginal Surface
• BED = 97.4 Gy
• EQD23 = 81.1 Gy
Dose to the Rectum (approx 5mm deep)
• EQD210 = 70.2 Gy
– 4.75-5 Gy per implant times active length
– Receives prescription dose of Cs-131 implant,
but to length of 1-1.5cm
All calculations performed using GEC-ESTRO LQ Worksheet. http://www.americanbrachytherapysociety.org
Patient Selection
How do we decide which type of implant to use?
Depth of the tumor
< 5mm: vaginal cylinder will do fine
5mm – 1cm: permanent implant using Cesium-131 or Gold-198
≥ 1cm: Syed-Neblett or other catheter based treatment
Vaginal Cylinder
Permanent Seeds
Syed-Neblett
Conclusions
UK first to utilize/investigate Cs131 permanent
interstitial implants for recurrent or new primary
gynecologic malignancies.
Actuarial local control rate at time of analysis
was 84.4%, exceeding other published rates
with minimal toxicity.
Interstitial implants with Cs-131 should be
more frequently and widely incorporated into
management of gynecologic malignancies,
including accessible recurrences following
previous RT.
So How Do I Perform One?
42 year old female diagnosed with Stage II clear cell
uterine cancer after TAH/BSO/LNS
Receives adjuvant therapy:
45 Gy to the Pelvis followed by 6 cycles of Carbo/Taxol
Within first month off therapy develops vaginal bleeding
Biopsy proven recurrence at vaginal apex
Treated with Vaginal brachytherapy 30Gy/10 fractions BID to the
surface
3 weeks post brachytherapy, exam demonstrates
progressive tumor at the vaginal apex
MRI confirms this is only site of disease
Scheduled for Exenteration with Gyn Oncologist
Treated instead with Interstitial Re-irradiation using Cesium-131
2.5cm
4cm
Description of Procedure
Gross tumor volume to be implanted determined
based on three-dimensional tumor
measurements based on pelvic exam and
imaging
Total activity, seed strength, and geometry
calculated using Paterson-Parker rules
Outpatient procedure in the Radiation Oncology
Department
Premedication: 5-10 mg po Diazepam
Local anesthesia: 2% lidocaine ± epinephrine
Individual seed applicators to insert each seed
Plan to deliver 55 Gy to 3 x 4.5cm ellipse
A
3cm
B
4.5cm
1. Determine the Area: π * A * B = π * 1.5 * 2.25 = 10.6 cm
2. Determine the necessary activity to deliver 10 Gy in Radium equivalent
3. Convert the activity in Radium equivalent to activity in Au-198:
8.25 R-cm2/mg-hr * 250 mg-hrs * 55 Gy = 51.09 mCi of Au198
2.38 R-cm2/mg-hr 93.3 mg-hrs
10 Gy
4. Convert the activity in Au-198 into activity in Cs-131 using conversion
factor of 1.1:
51.09 mCi of Au-198 * 1.1 = 56.19 mCi of Cs-131
5. Determine the number of seeds necessary to perform the implant:
Using Paterson-Parker Rules
Area <25 cm2
2/3 in the peripheral, 1/3 central
Circumference = 11.89 cm
Spacing seeds evenly at 1cm increments – 12 seeds will be
needed
If 2/3 = 12, then 1/3 will equal 6
So total number of seeds = 18
6. Determine the activity needed per seed:
Total activity = 56.19 mCi of Cs-131 = 3.12
mCi/seed
Seed count
18 seeds
7. Convert to Air-Kerma Strength using factor of 0.638:
Air-Kerma Strength = 3.12 mCi/seed * 0.638 u/mCi = 1.99 u/seed
So, we need to order 18 seeds at 1.99 u/seed to deliver
55 Gy to 5mm depth
- I usually order 10% extra in order to account for tumor
growth between calculation and implant date
- So we ordered #21 seeds