A Safety and Efficacy Study of Intra-tumoural Diffusing Alpha Radiation Emitters (DaRT) for the Treatment of Primary and Recurrent Squamous Cell Carcinoma of the Vulva

Squamous cell carcinoma of the vulva is a rare cancer accounting for less than 1% of female cancers. The disease predominantly affects women over the age of 65 although the incidence in younger women is rising, a finding that has been attributed to the effect of increasing human papillomavirus (HPV) infection .

The standard treatment for the primary tumour is surgical excision with the aim of achieving a 1 cm clear margin on histopathology. This requires the surgeon to remove 1.5-2 cm of surrounding normal tissue to allow for shrinkage after tissue fixation. Depending on the size and location of the tumour, the surgical procedure could vary from a wide local excision to a radical vulvectomy, including excision of adjacent structures such as the clitoris, lower urethra or anus, and/or reconstructive surgery. Wound infection and breakdown are common short-term complications of radical vulva surgery. Long term consequences include functional, cosmetic, psychological and psychosexual sequelae, which can have a significant negative impact on quality of life.

Recurrence rates for vulva squamous cell carcinomas range from 15% to 33%. Local recurrence in the vulva is the most common site of relapse (70%) with the groin nodes affected in 24%, pelvic nodes in 16% and distant metastases in 19%. The treatment of choice for local recurrence is surgical excision and 5-year survival rates of up to 45% have been reported. However, patients can develop multiple recurrences over a period of time and the feasibility of surgery becomes increasingly more limited as more and more tissue is removed.

Brachytherapy is a form of radiotherapy where radiation sources are placed directly in contact with or into (interstitial) cancerous tissue. The radiation emitted has a short range in tissue and the brachytherapy dose distribution conforms tightly to the location of the sources with minimal dose to the surrounding healthy tissues.

Alpha Tau Medical Ltd. proposes a novel treatment for malignant tumours using intra-tumoural alpha radiation, which is delivered using the Alpha DaRT Device (Alpha DaRT applicator + Alpha DaRT seeds). The technique, known as Diffusing Alpha-emitters Radiation Therapy (DaRT), combines the advantages of conventional interstitial brachytherapy with the destructive power of alpha particles.