Penile cancer brachytherapy

Abstract

Background

Squamous cell cancer of the penis is an uncommon, aggressive malignancy whit an age-adjusted annual incidence of one out of every 100,000 men. Surgical amputation (penectomy) has been considered the gold standard for the treatment of penile cancer, but is associated with a high level of psychosexual morbidity. Low-dose-rate brachytherapy (BT) consists of either manually afterloaded 192Ir or pulse-dose-rate (PDR) brachytherapy provides an organ-sparing alternative, preserving penile morphology and functionality in selected patients without compromising cure.

Patients

Tumours T1 and T2 N0, up to 4[[ce:hsp sp="0.25"/]]cm, strictly limited to the glans and not extended beyond the balano-preputial sulcus are most suitable for BT.

Materials

Pre-drilled Lucite templates and needles.

Implant procedure

A Foley catheter is inserted to determine the exact position of the urethra. The Paris System of dosimetry is used as a basis for designing the geometry of any individual implant to meet the requirements of tumour configuration. The distribution, spacing (median 15[[ce:hsp sp="0.25"/]]mm) and total number of needles depend on tumour size. The needles are positioned in a square or rectangular array. Planes are oriented with the needles passing from the dorsal to the ventral surface of the glans. Pre-drilled Lucite templates are used for guidance of needle placement and to maintain parallelism through the duration of the implant. A Styrofoam collar is positioned around the base of the penis for support and to minimize unnecessary irradiation of adjacent structures.

Treatment planning

The gross tumour volume (GTV) includes all visible and palpable tumour. The clinical target volume (CTV) encompasses the GTV plus a safety margin of 5–10[[ce:hsp sp="0.25"/]]mm. According to the Paris system, prescription is to 85% of the dose rate minima between the planes. The prescribed dose is generally 60[[ce:hsp sp="0.25"/]]Gy with the treatment completed in about 5 days.

Results

Local control rates obtained with BT ranging 72–80% at 10 years. The penile preservation rate is approximately at 70% at 10 years. The two most common late complications are: urethral meatal stenosis (9–45%) and soft tissue necrosis (6–26%).

Conclusions

Interstitial brachytherapy is a relatively simple and effective treatment of penile cancer, with results similar to those obtained with surgery in T1–T2 N0 M0, with high rates of organ preservation and acceptable toxicity.