The initial experience of electronic brachytherapy for the treatment of non-melanoma skin cancer

HDR brachytherapy in keratinocyte skin carcinomas - Single center experience with analysis of clinical, dosimetric, and radiobiological factors in acute skin toxicity

PURPOSE

Radiotherapy techniques have been utilized to treat keratinocyte skin carcinoma (KSC). The objective of this study was to report the results of patients with KSC treated with HDR brachytherapy, with a variety of techniques and applicators. A statistical analysis of clinical, radiobiological, and technical factors has been made to analyze those factors related to skin acute toxicity, focused on acute epithelitis G3.

METHODS AND MATERIALS

Between February 2005 and August 2020, 93 patients with 120 histologically proven KSC have been treated in our Institution. BT treatment has been performed using superficial BT/plesiotherapy (Valencia applicator (22%), flaps (48%), customized molds (4%) or interstitial techniques (26%)). The indications of BT were primary/definitive in 38 treatments (32%) or adjuvant/postoperative in 82 (68%). In 14 (17%) of the 82 operated patients a skin graft. Mean comparison t tests were performed for quantitative variables, and percentage comparison Chi2 tests for qualitative. Multivariate binomial logistic regression models were done.

RESULTS

Median follow-up was 36.5 months (range 5-141). Local control was achieved in 110 treatments (92%). Acute toxicity, dermatitis, was G1 7%; G2, 57% and G3 38%. The main factors statistically associated to the appearance of dermatitis G3 were the total dose, the volume treated, and the use of manufactured flaps. The main protective factor against dermatitis G3 was implant of skin graft.

CONCLUSIONS

In KSC BT the use of manufactured flap is accompanied by greater EG3, only with a relationship with the volume of treatment and total dose.

Acute and late complications and toxicities of skin brachytherapy

Skin cancer is the most prevalent malignancy, and its incidence is rising. Surgery is the primary treatment, however, morbidity of surgical resection in certain parts of the body warrant alternate treatment options such as radiation therapy. Complex topology of the skin can pose a challenge for treatment with photon and electron external beam radiotherapy techniques. Brachytherapy can be an attractive radiotherapy technique for these regions. Furthermore, brachytherapy results in lower dose to the underlying deep organs. The goal of this manuscript is to provide a brief overview of the role of brachytherapy for skin malignancies and to outline potential acute and long-term toxicities.

Benchmarking failure mode and effects analysis of electronic brachytherapy with data from incident learning systems

PURPOSE

Failure modes and effects analysis (FMEA) is a prospective risk assessment tool for identifying failure modes in equipment or processes and informing the design of quality control systems. This work aims to benchmark the performance of FMEAs for electronic brachytherapy (eBT) of the skin and for breast by comparing predicted versus actual failure modes reported in multiple incident learning systems (ILS).

METHODS AND MATERIALS

Two public and our institution's internal ILS were queried for Xoft Axxent eBT-related events over 9 years. The failure modes and Risk Priority Numbers (RPNs) were taken from FMEAs previously performed for Xoft eBT of nonmelanoma skin cancer and breast intraoperative radiation therapy (IORT). For each event, the treatment site and primary failure mode was compared with the failure modes and RPNs from that site's FMEA.

RESULTS

49 events involving Xoft eBT were identified. Thirty-one (63.3%) involved breast IORT, and 18 (36.7%) involved the skin. Three events could not be linked to an FMEA failure mode. In 87.7% of events, the primary failure mode ranked in the FMEA top 10 by RPNs. In 83.3% of skin events, the failure modes ranked in the top 10 by RPN or severity. In 90.3% of IORT events, the failure modes ranked within the top 10 by RPN or severity.

CONCLUSIONS

Evaluating FMEA failure modes against ILS data demonstrates that FMEA is effective at predicting failure modes but can be dependent on user experience. ILS data can improve FMEA by identifying potential failure modes and suggesting realistic occurrence, detectability, and severity values.

High-dose-rate brachytherapy using Leipzig applicators for non-melanoma localized skin cancer

Purpose

Technological advances with commercial production of surface applicators allowed high-dose-rate (HDR) afterloading brachytherapy to overpass challenges associated with the delivery of superficial radiation when treating non-melanoma skin cancer (NMSC). We reviewed our single institutional experience using HDR to treat basal (BCC) and squamous cell (SCC) carcinomas.

Material and methods

A retrospective review of all patients treated with HDR and Leipzig-style applicators for NMSC at the Radiation Oncology Department, AC Camargo Cancer Center, from March 2013 to December 2018 was performed.

Results

Seventy-one patients with 101 lesions (BCCs, 69.3% or n = 70) and median age 80 (range, 51-102) years old were evaluated. The median follow-up was 42.8 (range, 12-82) months. The 3-year and 5-year actuarial local control (LC) rates were 97.9% and 87.2%, respectively. On univariate analysis, treatments with EQD₂ less than 50 Gy (p < 0.001) and dose per fraction smaller than 3 Gy (p < 0.001) were found to be statistically significant predictive factors of a worse outcome. On multivariate analysis, SCC had a worse prognosis over BCC (p = 0.007, HR = 2.3, CI: 1.2-6.6). All patients developed some degree of acute side effects graded 1 to 2. Grade 3 acute side effects were observed in 9 (8.9%) patients. Moreover, severe late side effects (grade 3), hypopigmentation, and telangiectasia were observed in 4 (3.9%) patients. No grade 4 acute or late side effects were seen in this cohort.

Conclusions

HDR offers a convenient treatment schedule for patients and is associated with excellent LC. The most effective regimen, in terms of dose and fractionation, to treat superficial NMSC with HDR remains uncertain, but a moderate minimum EQD₂ dose of 50 Gy should be used.

The American Brachytherapy society consensus statement for skin brachytherapy

PURPOSE

Keratinocyte carcinoma (KC, previously nonmelanoma skin cancer) represents the most common cancer worldwide. While surgical treatment is commonly utilized, various radiation therapy techniques are available including external beam and brachytherapy. As such, the American Brachytherapy Society has created an updated consensus statement regarding the use of brachytherapy in the treatment of KCs.

METHODS

Physicians and physicists with expertise in skin cancer and brachytherapy created a consensus statement for appropriate patient selection, data, dosimetry, and utilization of skin brachytherapy and techniques based on a literature search and clinical experience.

RESULTS

Guidelines for patient selection, evaluation, and dose/fractionation schedules to optimize outcomes for patients with KC undergoing brachytherapy are presented. Studies of electronic brachytherapy are emerging, although limited long-term data or comparative data are available. Radionuclide-based brachytherapy represents an appropriate option for patients with small KCs with multiple techniques available.

CONCLUSIONS

Skin brachytherapy represents a standard of care option for appropriately selected patients with KC. Radionuclide-based brachytherapy represents a well-established technique; however, the current recommendation is that electronic brachytherapy be used for KC on prospective clinical trial or registry because of a paucity of mature data.

Effectiveness of radiotherapy for head and neck skin cancers: a single-institution study

Purpose

External beam radiotherapy (EBRT) is a useful option to treat head and neck skin cancer patients who are not indicated for surgery. In this study, we evaluated the treatment outcomes of EBRT in an Asian population.

Materials and Methods

The records from 19 head and neck skin cancer patients (10 with squamous cell carcinoma and 9 with basal cell carcinoma) who were treated with definitive or adjuvant EBRT from 2009 to 2017 were retrospectively reviewed. The radiotherapy doses administered ranged from 50 to 66 Gy (median, 55 Gy) with 2.0–2.75 Gy per daily fraction (median, 2.5 Gy). The T stage at presentation was as follows: Tis (1 patient), T1 (11 patients), T2 (6 patients), and T3 (1 patient). None had regional lymph node disease or distant metastasis at presentation. The local failure-free survival (LFFS) rates, toxicity, and cosmetic results were analyzed.

Results

The median age was 75.5 years (range, 52.6 to 92.5 years). The median follow-up duration from the completion of radiotherapy was 44.9 months (range, 5.8 to 82.6 months). One local failure occurred in a patient with a 2.1-cm posterior neck squamous cell carcinoma at 32.5 months after radiotherapy (1/19, 5.3%). The 3-year LFFS rate was 91.7%. No patients died from skin cancer during follow-up, and no grade 3 complications occurred. The cosmetic outcomes were excellent for 16 (84.2%) and good for 3 (15.8%) of the 19 patients.

Conclusion

EBRT offers good local control and cosmetic outcomes in patients with head and neck skin cancer, with no grade 3 complications.

Efficacy of hypofractionated radiotherapy in patients with non-melanoma skin cancer: Results of a systematic review

Radiation oncologists are increasingly tasked with the management of elderly patients with non-melanoma skin cancer, unsuitable for surgical intervention due to inoperable lesions and/or poor performance status. In this cohort, hypofractionated radiotherapy, delivered either daily, alternative daily or once weekly is highly effective. A systematic literature search was conducted of PUBMED, MEDLINE and EMBASE databases using the algorithm ('radiotherapy' OR 'radiation therapy' OR 'brachytherapy') AND ('hypofraction' OR 'hypofractionated' OR 'hypofractionation') AND ('skin neoplasms' OR 'carcinoma' OR 'malignancy') AND ('skin' OR 'epidermis' OR 'epidermal' OR 'cutaneous'). Forty relevant publications (1983-2017) encompassing 12,337 irradiated lesions were retrieved. Studies documented a mean age of 71.73 years and male predilection (54.5%). Both external beam radiotherapy and brachytherapy were utilized. Tumour subtype was squamous cell carcinoma (23.5%), basal cell carcinoma (75.2%) or others (1.3%). Irradiated lesions were primary (or denovo) (92.6%), located on the head and neck (95.7%) and received definitive therapy (96.5%). Analysis demonstrated a mean weighted total radiotherapy dose (38.15 Gy), dose per fraction (7.95 Gy) and treatments per week (2.98). Despite significant heterogeneity in the study population, the radiotherapy delivered and follow-up, local recurrence rate (crude or Kaplan-Meier analysis) did not exceed 7.9% in all but three of the 36 publications providing these data. Twenty-nine publications documented local control exceeding 90%. There is a body of evidence documenting the efficacy of hypofractionated radiotherapy as an option that confers no obvious disadvantage in local control when compared to traditional more protracted radiotherapy schedules.

Recommendations of the Spanish brachytherapy group (GEB) of Spanish Society of Radiation Oncology (SEOR) and the Spanish Society of Medical Physics (SEFM) for high-dose rate (HDR) non melanoma skin cancer brachytherapy

Clinical indications of brachytherapy in non-melanoma skin cancers, description of applicators and dosimetry recommendations are described based on the literature review, clinical practice and experience of Spanish Group of Brachytherapy and Spanish Society of Medical Physics reported in the XIV Annual Consensus Meeting on Non Melanoma Skin Cancer Brachytherapy held in Benidorm, Alicante (Spain) on October 21st, 2016. All the recommendations for which consensus was achieved are highlighted in blue. Regular and small surfaces may be treated with Leipzig, Valencia, flap applicators or electronic brachytherapy (EBT). For irregular surfaces, customized molds or interstitial implants should be employed. The dose is prescribed at a maximum depth of 3-4 mm of the clinical target volume/planning target volume (CTV/PTV) in all cases except in flaps or molds in which 5 mm is appropriate. Interstitial brachytherapy should be used for CTV/PTV >5 mm. Different total doses and fraction sizes are used with very similar clinical and toxicity results. Hypofractionation is very useful twice or 3 times a week, being comfortable for patients and practical for Radiotherapy Departments. In interstitial brachytherapy 2 fractions twice a day are applied.

Does ultrasound measurement improve the accuracy of electronic brachytherapy in the treatment of superficial non-melanomatous skin cancer?

Purpose

Electronic brachytherapy (eBT) is a form of contact radiation therapy used for thin superficial non-melanomatous skin cancers (NMSCs). An accurate measurement of diameter and depth is important for eBT treatment planning. Therefore, we compared clinical measurements by an experienced physician to measurements obtained using ultrasound (US), an objective imaging modality, in order to determine if clinical measurements were accurate enough for adequate NMSC treatment.

Material and methods

Eighteen patients with 20 biopsy-proven NMSCs first had a clinical examination and then an US evaluation prior to starting eBT. One physician provided a clinical measurement for diameter and depth based on physical examination during radiation oncology consultation. The patients then had an US evaluation with a 14 or 18 MHz US unit, to determine both the diameter and depth measurements; eBT dose prescription was done using the US derived measurements. The clinical measurements and US measurements were compared using a t-test.

Results

Seventeen lesions were basal cell carcinoma and 3 lesions were squamous cell carcinoma. The most common location was the nose (10 lesions). The difference between the clinical and the US derived measurements for the second largest diameter was found to be statistically significant (p = 0.03), while the difference for the largest diameter of the lesions was not (p = 0.24). More importantly, the depth measurements obtained with US were also found to be significantly different from the clinical estimates (p = 0.02). All patients have had a complete response to therapy with a median follow-up of 24 months.

Conclusions

Statistically different measurements were obtained in 2 of 3 parameters used in choosing applicator size and prescription depth using an US assessment. The data presented suggests that US is a more objective modality than clinical judgment for determining superficial NMSC diameter and prescription depth for personalized eBT planning.

Electronic brachytherapy management of atypical fibroxanthoma: report of 8 lesions

Purpose

To evaluate the suitability of treating atypical fibroxanthoma (AFX), an uncommon skin malignancy, with electronic brachytherapy.

Material and methods

From Feb 2013 to Sep 2014, we were referred a total of 8 cases of AFX in 7 patients, all involving the scalp. All of them were treated with electronic brachytherapy 50 Kev radiations (Xoft Axxent^®, Fremont, California). All lesions received 40 Gy in two fractions per week with 5mm margins.

Results

At a median follow-up of 23.7 months, the local recurrence rate is 12.5%. The single lesion that failed was not debulked surgically prior to electronic brachytherapy.

Conclusions

To our knowledge, this is the first report in the literature on the use of radiation therapy as curative primary treatment for AFX. No contraindication to the use of radiations is found in the literature, with surgery being the sole treatment for AFX noted. Our recurrence rate is 0% for debulked lesions. Risk of recurrence is mitigated with surgical debulking prior to brachytherapy. Electronic brachytherapy appears to be a safe and effective treatment for debulked AFX. Multiple excisions, skin grafting, and wound care can be avoided in elderly patients by the use of electronic brachytherapy.

Consensus for Nonmelanoma Skin Cancer Treatment, Part II: Squamous Cell Carcinoma, Including a Cost Analysis of Treatment Methods

BACKGROUND

Cutaneous squamous cell carcinoma (cSCC) is the second most common cancer in the United States. Cutaneous squamous cell carcinoma has an estimated incidence of more than 700,000 new cases per year and a 5% risk of metastasis.

OBJECTIVE

To provide clinicians with guidelines for the management of cSCC based on evidence from a comprehensive literature review and consensus among the authors.

MATERIALS AND METHODS

The authors conducted an extensive review of the medical literature on treatment methods for cSCC, taking into consideration cure rates, recurrence and metastatic rates, aesthetic and functional outcomes, and cost effectiveness of the procedures.

RESULTS

Surgical treatments provide the best outcomes for cSCC. Mohs micrographic surgery is a cost-effective procedure that affords the highest cure rate, maximal tissue preservation, and superior cosmetic outcomes. Nonsurgical methods may be used as a primary treatment for low-risk squamous cell carcinomas, but the cure rates are lower.

CONCLUSION

The cure rate remains the most important consideration in choosing the treatment method, but additional factors, such as the patient's general medical condition, psychosocial circumstances, the location of the tumor and cost effectiveness of the therapy should be considered. Mohs micrographic surgery remains the preferred treatment for high-risk tumors and tumors located in cosmetically sensitive areas.

Novel treatment options for nonmelanoma skin cancer: focus on electronic brachytherapy

Nonmelanoma skin cancer (NMSC) is an increasing health care issue in the United States, significantly affecting quality of life and impacting health care costs. Radiotherapy has a long history in the treatment of NMSC. Shortly after the discovery of X-rays and ²²⁶Radium, physicians cured patients with NMSC using these new treatments. Both X-ray therapy and brachytherapy have evolved over the years, ultimately delivering higher cure rates and lower toxicity. Electronic brachytherapy for NMSC is based on the technical and clinical data obtained from radionuclide skin surface brachytherapy and the small skin surface applicators developed over the past 25 years. The purpose of this review is to introduce electronic brachytherapy in the context of the history, data, and utilization of traditional radiotherapy and brachytherapy.

Incorporation of Electronic Brachytherapy for Skin Cancer into a Community Dermatology Practice

OBJECTIVE

The introduction of an electronic brachytherapy delivery system into an existing general dermatology practice is described. Radiobiologic rational for the dose fractionation schedule is detailed.

DESIGN

A miniaturized 50keV x-ray tube and delivery system are United States Food and Drug Administration cleared for nonmelanoma skin cancer. The device is introduced into an existing multi-physician dermatology practice in a standard unshielded treatment room.

SETTING

A multi-site, multi-physician dermatology practice Results: Fifteen months following introduction of the system, a total of 524 nonmelanoma skin cancer patients have been treated. At 12.5 months follow-up, there have been four recurrences and cosmesis has been excellent.

CONCLUSIONS

Advances in radiobiology and radiotechnology permit the treatment course to be given in eight fractions over four weeks. Radiation therapy for nonmelanoma skin cancer can now be given in an office setting as an alternative to Mohs surgery for appropriately selected patients. Results are comparable or better than those of surgery. Advances in radiobiology and radiotechnology permit the treatment course to be given in as few as eight fractions over four weeks. Patients are pleased with the convenience of the short course of therapy given in the office.

A pilot study of ultrasound-guided electronic brachytherapy for skin cancer

PURPOSE

Electronic brachytherapy (eBT) has gained acceptance over the past 5 years for the treatment of non-melanomatous skin cancer (NMSC). Although the prescription depth and radial margins can be chosen using clinical judgment based on visual and biopsy-derived information, we sought a more objective modality of measurement for eBT planning by using ultrasound (US) to measure superficial (< 5 mm depth) lesions.

MATERIAL AND METHODS

From December 2013 to April 2015, 19 patients with 23 pathologically proven NMSCs underwent a clinical examination and US evaluation of the lesions prior to initiating a course of eBT. Twenty lesions were basal cell carcinoma and 3 lesions were squamous cell carcinoma. The most common location was the nose (10 lesions). A 14 or 18 MHz US unit was used by an experienced radiologist to determine depth and lateral extension of lesions. The US-measured depth was then used to define prescription depth for eBT planning without an added margin. A margin of 7 mm was added radially to the US lateral extent measurements, and an appropriate cone applicator size was chosen to cover the target volume.

RESULTS

The mean depth of the lesions was 2.1 mm with a range of 1-3.4 mm, and the mean largest diameter of the lesions was 8 mm with a range of 2.6-20 mm. Dose ranged from 32-50 Gy in 8-20 fractions with a median dose of 40 Gy in 10 fractions. All patients had a complete response and no failures have occurred with a median follow-up of 12 months (range of 6-22 months). Also, no prolonged skin toxicities have occurred.

CONCLUSIONS

A routinely available radiological US unit can objectively determine depth and lateral extension of NMSC lesions for more accurate eBT treatment planning, and should be considered in future eBT treatment guidelines.

Clinical and cosmetic outcomes in patients treated with high-dose-rate electronic brachytherapy for nonmelanoma skin cancer

PURPOSE

To retrospectively analyze clinical and cosmetic outcomes in patients treated for nonmelanoma skin cancer (NMSC) with high-dose-rate (HDR) electronic brachytherapy (EBT) using surface applicators.

METHODS AND MATERIALS

We identified 127 patients who had 154 NMSC lesions, 149 of which were basal cell carcinoma, treated with HDR EBT at our institution between July 2012 and March 2014. Lesions were treated to 40 Gy in 8 fractions. Local control, acute toxicity, late toxicity, and cosmetic outcomes were analyzed retrospectively. Acute and late toxicities were graded using the Common Terminology Criteria for Adverse Events, version 4.0. Cosmetic outcomes were graded using a standard scale based on the Radiation Therapy Oncology Group and European Organization for Research and Treatment of Cancer Late Radiation Morbidity Scoring Schema.

RESULTS

Median (range) follow-up from completion of treatment was 16.1 (3.4-34.8 months). The overall crude recurrence rate was 1.3% (n = 2). Grade 0 to 1 acute radiation dermatitis was observed in 52.6% of treated lesions (n = 81), grade 2 in 34.4% (n = 53), and grade 3 in 13.0% (n = 20). No acute toxicity greater than grade 3 was observed and all acute toxic events resolved after treatment. Grade 0 to 1 late toxicity was observed in 94.2% of cases (n = 145), and grade 2 in 5.8% (n = 9). No late toxicity greater than grade 2 was observed. Across the 152 controlled lesions, cosmetic results were excellent in 94.2% of treated lesions (n = 145), good in 3.3% (n = 5), fair in 0.7% (n = 1), and poor in 0.7% (n = 1).

CONCLUSIONS

HDR EBT confers promising local control, minimal toxicity, and excellent cosmesis in our institutional experience. It should be considered ideal for NMSC of the head and neck, particularly for basal cell carcinoma involving central facial locations where surgical cosmesis may be inferior.

Radiotherapy treatment for nonmelanoma skin cancer

Non-melanoma skin cancer is the most common malignancy in the USA, with an estimated 3.5 million cases per year. Treatment options include surgical excision, radiation therapy (RT), photodynamic therapy and topical agents. Although surgical excision remains the mainstay of therapy, RT offers an effective alternative. RT can be used as an adjunct to surgery in high-risk situations, or in cases where surgical excision would lead to impaired cosmesis and/or functional outcomes. Radiation treatment modalities for non-melanoma skin cancers are diverse. Studies in the literature have examined the clinical effects of a wide variety of modalities, areas of the body and dosages. The most common modalities include superficial or orthovoltage RT, electron beam therapy and high dose-rate brachytherapy. This article aims to review the diverse radiotherapy treatment modalities for non-melanoma skin cancers, focusing on tumor control and toxicity.

Electronic brachytherapy--current status and future directions

In the past decade, electronic brachytherapy (EB) has emerged as an attractive modality for the treatment of skin lesions and intraoperative partial breast irradiation, as well as finding wider applications in intracavitary and interstitial sites. These miniature X-ray sources, which operate at low kilovoltage energies (<100 kV), have reduced shielding requirements and inherent portability, therefore can be used outside the traditional realms of the radiotherapy department. However, steep dose gradients and increased sensitivity to inhomogeneities challenge accurate dosimetry. Secondly, ease of use does not mitigate the need for close involvement by medical physics experts and consultant oncologists. Finally, further studies are needed to relate the more heterogeneous dose distributions to clinical outcomes. With these provisos, the practical convenience of EB strongly suggests that it will become an established option for selected patients, not only in radiotherapy departments but also in a range of operating theatres and clinics around the world.

Nonmelanoma skin cancer treated with electronic brachytherapy: results at 1 year

PURPOSE

We report clinical outcomes at 1 year or more after high-dose-rate (HDR) electronic brachytherapy (EBT) using surface applicators for the treatment of nonmelanoma skin cancer (NMSC).

METHODS AND MATERIALS

From July 2009 to April 2012, 122 patients with 171 NMSC lesions were treated with EBT to a dose of 40Gy in eight fractions, delivered twice weekly. At followup, patients were assessed for acute and late toxicities, cosmesis, and local control.

RESULTS

Treatment of 171 lesions was completed in 122 patients with a mean age 73 years. There have been no recurrences to date with a mean followup of 10 months (range, 1-28 months). Followup data at 1 year or more were available for 46 lesions in 42 patients. Hypopigmentation (all Grade 1) was present in 5 (10.9%) of 46 lesions at 1 year. Other late effects at 1 year included dry desquamation, alopecia, and rash dermatitis, which occurred in 1 (2.2%), 1 (2.2%), and 3 (6.5%) of 46 lesions, respectively. No Grade 3 or higher adverse events were observed at any time point. Cosmesis was evaluated at 1 year for 42 of 46 lesions and was excellent for 39 (92.9%) and good for 3 (7.1%) of the 42 evaluable lesions.

CONCLUSIONS

Treatment of NMSC with HDR EBT using surface applicators was effective with no recurrences, good to excellent cosmesis, and acceptable toxicities at 1 year or more after treatment. HDR EBT provides a convenient nonsurgical treatment option for NMSC patients.