22 Penis cancer

Penis cancer

3

THE GEC ESTROHANDBOOKOF BRACHYTHERAPY | Part II Clinical Practice Version 1 - 15/07/2022

22 Penis cancer

Juanita Crook and Cyrus Chargari

1. Summary 2. Introduction 3. Anatomy 4. Pathology

3 3 3 3 4 5 5 5

9. Treatment planning

9 9

10. Dose, dose rate and fractionation

11. Monitoring

12 12 12 13 14

12. Results

5. Work up

13. Adverse side effects 14. Key messages

6. Indications, contra-indications 7. Tumour and target volume

15. References

8. Technique

1. SUMMARY

Penile cancer remains uncommon in western societies but over recent years, an etiologic path through Human Papilloma Virus (HPV) has altered demographics to implicate younger individuals. This has spurred motivation to turn away from traditional surgical management with penectomy or partial penectomy towards penile conserving approaches. Radiation, either in the form of external beam radiotherapy or brachytherapy, provides an effective means of penile sparing. Brachytherapy can be delivered as either interstitial or surface mold techniques, using either traditional low dose rate (LDR), pulsed dose rate (PDR) or high dose rate (HDR) approaches. Brachytherapy generally provides local control and penile sparing of 70-85% and cause-specific survival of 85-95% at 5 years. Penile amputation is reserved for treatment failures. We will review patient selection and the specialized techniques for various brachytherapy approaches.

2. INTRODUCTION

3. ANATOMY

There is considerable geographic variation in the incidence of penile cancer worldwide. The incidence in less developed nations such as India, China, Brazil and Uganda is up to 10 times that seen in developed nations [1][2]. The low incidence of penile cancer in western countries (approximately 1/100,000) has impeded clinical study of optimal management. The traditional risk factors of advanced age, smoking, lack of circumcision, phimosis, poor hygiene and lack of access to health care[1][2][3] are being superseded by HPV exposure which is now implicated in 45-50%of cases[4]. Sexual practices contribute to the increased prevalence of HPV in society but there is hope that widespread penetration of HPVmultivalent vaccination for both girls and boys will flatten that curve[5]. The increased responsiveness to radiation and chemoradiotherapy demonstrated by other HPV-positive squamous cancers such as oropharynx, cervix, vulva and anal canal, has promoted interest in these alternative forms of treatment. As the psychologic impact of penile amputation is considerable [6][7], penile-sparing approaches, both surgical and radiation, are encouraged.

The penis is comprised of two anatomical parts that are distinct in terms of topographic and functional aspects: the penile root, which is immobile and embedded in the superficial perineum, and the penile body, which is visible and mobile and is comprised of 3 erectile bodies. There are two cylindrical dorsolateral corpora cavernosa and one medio-ventral corpus spongiosum surrounding the urethra. The penile glans is the distal part of the corpus spongiosum, covered by the prepuce.The balano-prepucial sulcus, also known as the coronal sulcus, is the boundary between the penile glans and the penile body (Figure 1).

4. PATHOLOGY

Although other histologic types have been reported, including basal cell, lymphoma, melanoma and sarcoma, 95% of primary penile cancers are squamous cell (SCC). Overall HPVpositivity is reported in 40-50% but varies geographically, and with histologic subtype.