29 Skin Cancer

Skin Cancer

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THE GEC ESTROHANDBOOKOF BRACHYTHERAPY | Part II Clinical Practice Version 1 - 30/04/2017

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Skin Cancer Jose Luis Guinot, Jose Pérez-Calatayud, Erik Van Limbergen

1. Summary 2. Introduction

3 3 3 3 4 4 4 4

9. Treatment Planning

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10. Dose, Dose Rate, Fractionation

12 12 13 16 17 18

3. Anatomical Topography

11. Monitoring

4. Pathology 5. Work Up

12. Results

13. Adverse Side Effects

6. Indications, Contra-indications 7. Tumour and Target Volume

14. Key messages 15. References

8. Technique

1. SUMMARY

Non-melanoma skin cancer can be treated with brachytherapy as an alternative to surgery, with some advantages in dosimetry compared with external beam radiation due to the rapid fall-off of the dose. LDR is no longer available, and HDR looks for repro- ducing the good results achieved during decades. A standard optimal schedule for HDR is not well defined, and different options have been published. In superficial tumours, contact brachytherapy is simple and effective, with flaps, personalized moulds or surface applicators. The larger the area to be irradiated, the lower the dose should be per fraction. In carcinomas deeper than 5mm an interstitial technique with plastic tubes or needles is mandatory.

2. INTRODUCTION

There is no consensus on the standard techniques and required doses for skin brachytherapy. A report of the American Brachytherapy Society (ABS) on aspects of dosimetry and clinical practice of skin brachytherapy describes a dosimetric summary and different available approaches [4].

Non-melanoma skin cancer is a disease of older age, more than half of new patients are more than 65 year old. About one half of patients with a skin carcinoma will develop a new primary lesion within 5 years of the initial diagnosis. Due to a longer life expectancy, the incidence rate is increasing by 3-6% per year, and it is becoming epidemic [1]. Basal cell and squamous cell carcinomas of the skin usually occur on sun-exposed sites, the face being one of the sites of predilection, accounting for 95 % of cases. Surgery in these sites (nose, ears, eyelids, lips)may bemutilating or require complex plastic reconstruction techniques under general anaesthesia. Surgery and radiotherapy appear to be themost effective treatments with surgery showing the lowest failure rates [2]. Only one randomized trial [3] of surgery versus radiotherapy in basal cell carcinoma of the face had primary outcome data at four years, showing significantlymore persistent tumours and recurrences in the radiotherapy group as compared to the surgery group but using a mixture of techniques and fractionations. Radiotherapy and brachytherapy have been used successfully for years, as an alternative or complement to surgery. Brachytherapy offers several advantages in dosimetry, is easy to apply, and the use of the linear accelerators for skin cancer can be decreased. Carefully tailored brachytherapy is a good alternative, if not the treatment of choice, for those lesions that cannot be safely removed by surgery with primary wound closure under local anaesthesia. All these factors contribute to encourage the use of HDR-BT for cutaneous carcinomas.

3. ANATOMICAL TOPOGRAPHY

As most skin cancers arise in the face, they are usually diagnosed at an early stage. However, deep extension to the orbit, ear or bone should always be ruled out. Deep extension along an embryonic pathway should always be suspected, especially in case of tumours involving the naso-labial fold, and adequate deep safety margins for resection and for brachytherapy must be taken [5].

4. PATHOLOGY

Most skin cancers are basal cell (65%) or squamous cell (30%) carcinomas. Brachytherapy is not indicated for skin melanomas. Around 90%of lesions are small, less than 20mmand their thickness is limited to a few mm [4].