High dose brachytherapy with non sealed 188Re (rhenium) resin in patients with non-melanoma skin cancers (NMSCs): single center preliminary results.

Abstract

Background and aim High dose brachytherapy using a non sealed 188Re-resin (Rhenium-SCT®, Oncobeta® GmbH, Munich, Germany) is a treatment option for non-melanoma skin cancer (NMSC). The aim of this prospective study was to assess the efficacy and the safety of a single application of Rhenium-SCT® in NMSC. Materials and method Fifty consecutive patients (15F, 35 M, range of age 56–97, mean 81) showing 60 histologically proven NMSCs were enrolled and treated with the Rhenium-SCT® between October 2017 and January 2020. Lesions were located on the face, ears, nose or scalp (n = 46), extremities (n = 9), and trunk (n = 5). Mean surface areas were 7.0 cm2 (1–36 cm2), mean thickness invasion was 1.1 mm (0.2–2.5 mm), and mean treatment time was 79 min (21–85 min). Superficial, mean, and target absorbed dose were 185 Gy, 63 Gy, and 31 Gy respectively. Patients were followed-up at 14, 30, 60, 90, and 180 days posttreatment, when dermoscopy and biopsy were performed. Mean follow-up was 20 months (range 3–33 months). Early skin toxicity was classified according to Common Terminology Criteria for Adverse Events (CTCAE). Cosmetic results were evaluated after at least 12 months according to Radiation Therapy Oncology Group (RTOG) scale. Results At 6 months follow-up, histology and dermoscopy were available for 54/60 lesions, of which 53/54 (98%) completely responded. One patient showed a 1-cm2 residual lesion that was subsequently surgically excised. Twelve months after treatment, 41/41 evaluable lesions were free from relapse. Twenty four months after treatment, 23/24 evaluable lesions were free of relapse. In 56/60 lesions early side effects, resolving within 32 days were classified as grades 1–2 (CTCAE). In the remaining 4/60 lesions, these findings were classified as grade 3 (CTCAE) and lasted up to 8–12 weeks but all resolved within 90 days. After at least 12 months (12–33 months), cosmetic results were excellent (30 lesions) or good (11 lesions). Conclusion High dose brachytherapy with Rhenium-SCT® is a noninvasive, reasonably safe, easy to perform, effective and well-tolerated approach to treat NMSCs, and it seems to be a useful alternative option when surgery or radiation therapy are difficult to perform or not recommended. In our population 98% of the treated lesions resolved completely after a single application and only one relapsed after 2 years. Larger patients’ population and longer follow-up are needed to confirm these preliminary data and to find the optimal dose to administer in order to achieve complete response without significant side effects.

A novel tool for predicting the dose distribution of non‐sealed 188Re (Rhenium) resin in non‐melanoma skin cancers (NMSC) patients

“…The target is contoured directly on the plastic foil by an expert dermatologist, with a safe margin of 3 mm. The entire clinical workflow is described in Castellucci et al 3 …”

“…The tool for resin application is designed to apply the radioactive matrix with a brush shielded with tungsten 2 . The dedicated shielded brush enables the radioactive resin application on an adhesive 7 µm plastic foil placed over the skin lesion to avoid the contamination of the patient's skin 3 . The carpoule activity is measured before and after the resin application using an ad hoc activity calibrator (Comecer, Bologna Italy) provided by Oncobeta.…”

“…To prevent undesired skin contamination, the resin is applied on a 7 µm foil placed over the skin lesion instead of directly on the patient skin. This approach has been shown to be highly effective, highly tolerable, and minimally invasive 2–4 …”

“…This approach has been shown to be highly effective, highly tolerable, and minimally invasive. [2][3][4] From a dosimetric point of view, the standard approach reported in Refs 2, 3 is based on the use of VARSKIN. The VARSKIN software is a reference tool for skin contamination dosimetry assessments approved by the U.S. Nuclear Regulatory Commission.…”

Fundamentals of Rhenium-188 Radiopharmaceutical Chemistry

“…Similarly, the local application of 188 Re skin cream for brachytherapy of non-melanoma skin cancer (NMSC) [ 62 , 63 ] also relies on physical methods of localization and does not involve systemic administration and localization through a vector at the target site. With both therapies, positive clinical results and no severe complications are reported.…”