High-dose-rate brachytherapy for localized penile cancer: Evolution of a technique

High-dose-rate (HDR) brachytherapy is a convenient treatment option for selected patients with T1-T2 penile squamous cell carcinoma (SCC), providing high rates of penile preservation and tumor control. We present the results of penile SCC treated with HDR brachytherapy either interstitially or via a surface mold.

Between November 2009 and April 2019, seven patients (2 T1a and 5 T2) were treated with interstitial HDR and 8 (1 Tis, six T1a, and one T1b) with surface mold. Prescribed dose for interstitial patients ranged from 38.4 Gy in 6 days (3.2 Gy × 12) to 53 Gy in 9 days (3.12 × 17), BID. All patients treated with mold brachytherapy received 40 Gy in 10 fractions BID. Toxicity and oncological results were assessed for both groups, and their relation with dosimetry is described.

Median follow up was 90 months for interstitial and 27 months for those treated with surface mold. Fourteen of 15 patients are alive and disease-free; one surface mold patient died of non-small-cell lung cancer. There was one relapse in each group, each treated with salvage penectomy. The potency was preserved in 82%. For interstitial, G2 necrosis occurred in 43%, G2 meatal stenosis in 29% and G3 stenosis in 14%.

Both techniques have excellent rates of tumor control and organ preservation. Implant geometry and homogeneity constraints must be carefully designed to minimize toxicity in interstitial brachytherapy. Urethral contouring and reporting of dosimetric parameters should be defined.