penile brachytherapy technical aspect post implant issue

1. JOUNAL CLUB
PARAG ROY
LOK NAYAK HOSPITAL

3. Introduction
• Brachytherapy effective penile-conserving option for management of T1- T2 and
selected T3
• Deliver a high dose (60 Gy) over short period of time (4- 5 days) with a high degree
of accuracy
• Alternative -EBRT, but penile positioning for access to the beam while avoiding
dose OAR and to encase the organ in tissue-equivalent material to ensure full dose
to the skin surface.
• Brachytherapy spares more of the penile shaft, well tolerated
• Skin reaction develops after the treatment has been completed.

4. Material and Methods
• From 1989 to 2009, Princess Margaret hospital and Ottawa Hospital Cancer
Center used brachytherapy to treat penile SCC
• Total 75 cases
• From 1989 to 1998, manual afterloading was used with 192Ir wire or seeds,
and from 1999 to 2009 pulse dose rate automated afterloading.
• 60 Gray is delivered over a period of 4-5 days

5. Patient selection
• Ideally, T1 and T2 tumors up to 3 cm in maximum diameter
• Larger tumors up to 4e 4.5 cm in maximum diameter with understanding
the risk
• Tumors involve the glans and/or foreskin
• Circumcision should be undertaken for all cases

6. Dosimetry
• Used Paris System
• Needles and planes should be equally spaced and parallel.
• Ideally, spacing should be no less than 12 mm and no greater than 18 mm. For penile cancer, 14-18 mm is the
best.
• Parallelism and spacing should be maintained by rigid predrilled templates.
• The dose rate minimum is calculated between adjacent planes (basal dose rate), and the prescription isodose
(reference isodose) is calculated at 85% of the dose rate minimum.
• Hyperdose sleeve (170% of basal dose or twice the prescription isodose).
• Diameter of the hyperdose sleeve is less than 10 mm

7. Schematic of two-plane, six-needle implant, showing the calculation of the isodose location as per the
Paris System rules.

8. • Dwell times at the corners of the implant are highest and those at the center
of the implant are lowest.
• This spares the urethra by reducing the dose and makes the diameters of the
hyperdose sleeves around the needles more uniform

9. Testicular dose
• Wishing to maintain fertility, lead can be added to both sides of the
styrofoam collar that supports the penis during the duration of the implant
• Thermoluminescent dosimeter on the scrotum the dose measured and not
not exceed 2 Gy.

10. Target definition
• GTV (gross tumor volume) includes all visible and palpable tumor.
• CTV should include a margin of 8-10 mm around clinically evident tumor.
• In terms of lateral margins, if the most lateral needles are placed
approximately 3 mm beyond the obvious tumor, the additional isodose
margin (0.27X the intersource spacing) will provide adequate coverage with
the prescription isodose (with an additional 2-3 mm to the 50-Gy isodose).

11. Needle placement
• Single-plane implants are rarely done due to depth of invasion
• Volume implant, two or three parallel planes of sources are inserted
• Four (2x2), six (2x3), or nine (3x3)needles may be required.
• Catheterization at the beginning of the procedure helps to identify urethra
• 19.5-Gauge needles are used in association with manually afterloaded 192 Ir
wire, and 17.5-gauge needles are compatible with a PDR remote afterloader

12. Symmetric tumor/small glans
• Circumferential tumor , treat the entire glans.
• In a small glans, a 2-plane implant performed
with four needles and 18-mm spacing.
• The needles pass from the dorsal to ventral
surface and bracket the urethra.
• They should not be any deeper than 3 mm
from the skin surface.
• Compression can be used when inserting the
needles to ensure correct depth

13. Symmetric tumor/wide glans
• A wider glans cannot be encompassed with four
needles in a 2x2 array
• A three-plane implant would often be ideal in
terms of coverage but cannot be used (urethra)
• Consequently, a four-plane implant can be
constructed, with two central planes bracketing
the urethra (these planes will be too deep to
adequately treat the skin surface)
• Two lateral planes entirely exterior to the penis,
with tissue-equivalent bolus between the
needles and the skin surface

14. Asymmetric tumor
• When the tumor is well localized to one side of the
glans, a three-plane implant can be used,
• two planes are on the involved side, and the third
plane is just lateral to the urethra on the uninvolved
side.
• This will allow some skin sparing on the uninvolved
side, as this plane will be quite deep to the skin
surface but will still provide adequate margins in
treating the tumor

15. Perimeatal tumor
• Because of the curvature of the end of the glans. Even with
fairly close 15-mm spacing, tissue may bulge outside of the
expected location of the isodoses.
• Needles that are too close to the meatus increase the risk of
subsequent meatal stenosis.
• Solution- Position a proximal pair of needles several
millimeters behind the meatus and then to construct an
exterior plane distal to the glans
• Bolus between the exterior needles and the glans.
• This ensures adequate coverage both at a depth and at the
most distal perimeatal site.

16. Dose
• Prescribed dose is generally 60 Gy at a classic LDR of 50- 60 cGy/h
(<1Gy/h) and is delivered over 100-120 hours (4-5 days).

17. Acute and Late reaction
• Acute-
• Moist desquamation peaks after the treatment is finished, usually in about 2-3 weeks,
but may take 2-3 months to heal completely.
• Adhesions in urethra
• Late-
• soft tissue necrosis
• meatal stenosis

18. Soft tissue necrosis
• Soft tissue necrosis is reported in up to 23% of patients (In this study 14%)
• Common after brachytherapy than EBRT
• Necrosis is the most common reason for failure of penile conservation in a tumor-free penis.
• Rozan et al . reported that 11 of 34 total or partial amputations were performed because of
posttreatment soft tissue necrosis and risk of necosis/ fibrosis increased with increasing dose
over 60 Gy
• No necrosis is seen when the brachytherapy dose was limited to 50 Gy but not effective dose for
optimal tumor control.
• An increased risk of necrosis has been reported with T3 tumors and with higher-volume
implants (>30 cc) with more needle planes (number of planes> 2)

19. Meatal stenosis
• Meatal stenosis is reported in 10-45% of patients (in this study 9%) and
tends to occur later in the follow up period, but usually before 3 years.
• It was related to the number of needle planes used in the implant (more than
two planes) but more likely depends on the proximity of the needles to the
meatus and distal urethra.
• Optimization of dwell times can limit the urethral dose

20. Cosmesis and Function
• Cosmesis is good to excellent.
• Patchy hypo- or hyperpigmentation
• Telangiectasia may appear
• As the penile shaft and corpora have not been irradiated, erectile function is
generally maintained

21. Results
• 5-yearlocal tumor control rates of 70-86% and penile preservation rates at 5
years ranging from 72% to 88%
• Previously reported experience of same center over 16 years with 67 cases
has yielded a 10-year actuarial overall survival of 59%, cause-specific survival
of 83.6%, and actuarial penile preservation rates at 5 and 10 years of 88%
and 67%, respectively

22. Conclusion
• Interstitial brachytherapy for penile cancer is a relatively simple and highly
effective penile-conserving option for T1, T2, and selected T3 squamous
carcinomas of the penis.
• Lack of awareness on the part of the urologists and lack of experience on
the part of the radiation oncologists are the major barriers to its use