Personalized High-Dose-Rate Brachytherapy with Non-Sealed Rhenium-188 in Non-Melanoma Skin Cancer

Abstract

Objectives: Most non-melanoma skin tumors are treated with conventional methods, being the most common surgery. However, satisfactory surgical treatment can be very challenging for patients with large or multiple lesions. In cases where the tumor is located on the face, hands or genital areas, the results may be suboptimal in terms of aesthetics and/or function. A high dose-rate brachytherapy using non-sealed Rhenium-188 was developed to offer a personalized solution for these cases as well as cases where a surgical approach was not preferred. Here we show a retrospective analysis of 43 patients treated with this technique. Methods: The technique, called dermatological high-dose-rate beta-brachytherapy (DBBR), is a brachytherapy based on a non-sealed beta-emitter embedded in a complex specially-designed acrylic matrix. We use Rhenium-188 as the betaemitter. This matrix is applied over the tumor, which is protected by a special thin plastic foil avoiding any direct physical contact of the radioisotope with the skin. After the calculated required amount of time, the protective foil with the applied radioactive acrylic matrix is removed. 43 patients (basal/squamous cell carcinomas, BCCs and SCCs) were treated with this technique after histological confirmation of the non-melanoma skin tumor. Patients were then followed up, to evaluate wound healing as well as potential side-effects and recurrences. Results: 29 BCC and 14 SCC patients were treated with DBBR. 36/42 achieved complete clinical remission with only 1 application (24 BCC, 12 SCC) and 6/42 with 2 applications (4 BCC, 2 SCC); 1 BCC patient was lost to follow-up before wound closing. In 4 of the 6 patients (3 BCC, 1 SCC) treated twice the second treatment was planned due to the thickness of the tumor; in the remaining 2 patients (1 BCC, 1 SCC) the second treatment was needed to treat a recurrence at the border of the previously treated area. No side effects were reported. Wound healing was complete in 34-180 days (average 65 days, median 53) for all 42 patients that were followed-up. An average follow-up of 288 days (after one or two treatments) showed no single recurrence (42 patients). Conclusions: DBBR is a very promising alternative for treatment of BCCs and SCCs for all cases in which a surgical approach is not recommended or accepted by the patient.

Rhenium-188 Labeled Radiopharmaceuticals: Current Clinical Applications in Oncology and Promising Perspectives

“…The inert matrix containing the 188 Re is able to adapt to every skin surface without contamination, imparting an accurate distribution of dose and sparing the healthy tissue. The technology was further improved, and, in a more recent study (225), 29 BCC and 14 SCC patients were treated. One patient was lost to follow-up before wound closing, but wound healing was complete for all other 42 patients (average 65 days), with no side effects to be reported.…”

Modification of the 4 MeV electron beam from a linear accelerator for irradiation of small superficial skin tumors

“…The most optimal radiation modality for treating superficial tumors with less than 0.5 cm invasion depth, would produce uniform dose distribution, easy protection of adjacent healthy structures, narrow penumbra, insensitivity to moderate density variations or complex surface geometry, and fast dose fall-off for areas deeper than 0.5 cm. The potential techniques include: X-ray contact therapy devices with tube voltage ≤ 50 kV, orthovoltage devices with tube voltage ≥ 150 kV, electron beams from the linear accelerators, superficial brachytherapy applicators with Ir-192 afterloaders, and radioactive superficial molds, like Re-188 paste [3] , [4] , [5] . None of the existing techniques includes all the optimal treatment features.…”