Brachytherapy, Skin Cancer

Indications

Brachytherapy offers several advantages over external-beam radiation therapy, including the delivery of higher radiation doses directly to the tumor, shorter overall treatment duration, and reduced radiation exposure to surrounding healthy tissue.[2] Clinical use includes both primary treatment and postoperative management for patients at risk of local recurrence.[3] Global utilization of brachytherapy for skin cancer continues to increase because of high cure rates and favorable cosmetic outcomes.

Indications include primary treatment for low-risk BCC and SCC in patients who are not surgical candidates or who decline surgery, offering an effective alternative in the setting of medical comorbidities or cosmetic concerns. Brachytherapy also serves as adjuvant therapy following surgical excision for high-risk or recurrent NMSCs. A particular benefit occurs in cosmetically sensitive areas, eg, the face, eyelids, nose, and ears, where surgical excision may compromise appearance or function. Palliative application can relieve symptoms and improve quality of life in advanced disease.[3]

Clinical recommendations frequently support brachytherapy for localized lesions in anatomically curved regions near critical structures, including the nasal bridge, periorbital region, and chest skin. This technique facilitates treatment of sizable tumors while limiting injury to adjacent healthy tissues and achieving high rates of local control without significant adverse local effects. In many recurrent cases following prior radiation therapy, brachytherapy represents the only viable therapeutic option.[4]

Contraindications

Brachytherapy remains an effective treatment option for many cases of NMSCs, yet careful evaluation of contraindications remains essential before treatment initiation. Contraindications to radiation therapy remain relatively limited and fall into 2 categories: absolute and relative.[5] Repeated irradiation after recurrence following an initial course of treatment can be performed with acceptable toxicity; however, the risk of a subsequent recurrence increases and depends mainly on the size of the recurrent lesion.[6]

Several genetic disorders represent absolute contraindications to brachytherapy because of heightened radiation sensitivity and an increased risk of severe adverse effects or secondary malignancies. These conditions include xeroderma pigmentosum, Gorlin syndrome, and untreated collagen vascular diseases. Use of brachytherapy in these populations carries substantial risk, warranting consideration of alternative therapeutic approaches. Treatment feasibility also depends on patient cooperation, as remaining still for approximately 5 to 10 minutes remains necessary during radiation delivery. Mild oral sedation may be required when cooperation proves challenging, eg, in patients with moderate to severe dementia. Severe movement disorders may limit suitability for radiation therapy and represent a relative contraindication.[5]

Equipment

Brachytherapy for the treatment of NMSC requires specialized equipment to support accurate and safe radiation delivery. The primary component is the brachytherapy source, which delivers radiation directly to the tumor and typically consists of radioactive isotopes, eg, iridium-192. An afterloader stores the radioactive source, provides shielding, and precisely advances the source to the designated treatment location.

Accurate source positioning relies on the use of applicators, ranging from simple surface molds to dedicated devices (eg, Valencia and Leipzig applicators) to more complex catheter-based systems, including Freiburg flaps, designed to conform to the treatment site. A treatment planning system plays a critical role in calculating dose distribution and optimizing radiation delivery to malignant tissue while minimizing exposure to surrounding healthy structures. These systems frequently integrate imaging modalities, eg, ultrasound or computed tomography simulators, to support the precise placement of the applicator and source. Safety equipment and shielding materials remain essential to protect patients and healthcare personnel from unnecessary radiation exposure. Collectively, these components enable safe and effective brachytherapy for NMSC.[7]

Personnel

The personnel involved in radiotherapy for NMSC typically include an interprofessional team. At the core of this team are radiation oncologists, who plan and oversee treatment. Medical physicists play a crucial role in ensuring the accuracy of radiation delivery by calibrating and maintaining equipment and assisting in the planning process.[8] Radiation therapists (also known as radiologic technologists) are responsible for positioning the patient and operating the radiation equipment during each session.

Dosimetrists work closely with the radiation oncologist and medical physicist to calculate the precise radiation dose needed to effectively treat the cancer while minimizing exposure to surrounding healthy tissue. Additionally, oncology nurses provide patient care, managing adverse effects and offering support throughout the treatment process. In some cases, dermatologists and surgical oncologists may also be involved, particularly in complex cases where an interprofessonal approach is necessary. This team works together to ensure the patient receives safe, effective radiotherapy tailored to their specific needs.[9]

Preparation

Preparing a patient for brachytherapy for skin cancer requires a detailed, precise approach to ensure the treatment is both effective and comfortable. The process starts with a thorough consultation, during which the patient’s medical history is reviewed and the specifics of the brachytherapy plan are discussed. This includes explaining the procedure, potential adverse effects, and any necessary lifestyle adjustments.

During the initial phase, a simulation session is conducted to plan the precise delivery of the radiation. This session may involve imaging techniques, eg, computed tomography scans or ultrasound, to accurately map the tumor and determine the optimal placement of the radioactive sources. Custom applicators or molds are often used to accurately position radioactive sources. These applicators are tailored to the shape and location of the skin cancer to ensure the radiation is delivered precisely to the tumor while minimizing exposure to surrounding healthy tissue.

Before the actual treatment, small, permanent skin markings or tattoos may be applied to delineate the treatment area. These markings help in aligning the applicators correctly during each session. The patient is then positioned appropriately based on the location of the skin cancer. This positioning is carefully verified using imaging studies to ensure accuracy and avoid misalignment during treatment.

Throughout the brachytherapy procedure, the patient is instructed to remain still to maintain the precise positioning of the applicators and radioactive sources. Radiation therapists monitor the patient from outside the treatment room and communicate via intercom to ensure the patient is comfortable and properly aligned. After each session, the treated area is assessed for any immediate reactions or adverse effects. Follow-up appointments are scheduled to monitor the patient’s progress, manage any complications, and evaluate the effectiveness of the therapy.[10]

Technique or Treatment

Beginning in the mid-1960s, direct implantation of radioactive sources into patients was discontinued because of unacceptable radiation exposure risks to radiation oncologists and clinical staff. Contemporary practice instead relies on the placement of nonradioactive tubes, catheters, or applicators into the target site, followed by loading radioactive sources using a technique known as afterloading.[2] Brachytherapy implants may be permanent or temporary and fall into 2 primary categories: low-dose-rate and high-dose-rate. Low-dose-rate brachytherapy involves prolonged implantation of radioactive sources that emit radiation slowly, with dose rates typically defined as 0.4 to 2 Gy/hour. High-dose-rate brachytherapy uses temporary source placement for brief periods, often lasting only a few minutes, with dose rates exceeding 12 Gy/hour, allowing precise control of radiation dose and treatment duration.[2]

Low-dose-rate brachytherapy sessions may extend from 3 to 5 days, requiring radiation safety precautions for individuals in close contact with the patient. High-dose-rate brachytherapy sessions typically range from 1 to 30 minutes and are commonly delivered in the outpatient setting. Compared with low-dose-rate techniques, high-dose-rate brachytherapy carries a greater potential for injury to adjacent normal tissues. To mitigate this risk, the total radiation dose is often divided into multiple fractions, ranging from a few to 30 to 40 sessions, with inter-fraction intervals of 1 to 28 days.[2] Surface-mold brachytherapy commonly serves as a treatment option for superficial tumors with well-defined margins. Flexible materials such as silicone or polymethyl methacrylate form molds that conform to the tumor surface, allowing the insertion of radioactive sources in a configuration that achieves uniform radiation dose distribution across the target volume.

Interstitial brachytherapy represents an invasive form of internal radiation therapy that involves direct placement of radioactive seeds or wires within the affected tissues. Compared with external radiotherapy, which often requires treatment courses lasting up to 6 weeks, interstitial brachytherapy offers substantially shorter treatment durations, in some cases as brief as 80 hours. Clinical application extends to anatomically complex regions such as the eyelid, where fabrication of precise surface molds for surface-mold brachytherapy may prove technically impractical.[2]

Radiation dose selection in brachytherapy depends on multiple factors, including tumor type and location, tumor size and stage, patient-specific characteristics, and overall treatment objectives. Dose prescriptions aim to deliver adequate radiation to malignant tissue while limiting exposure to surrounding healthy structures. Dose calculation and delivery rely on both manual methods and advanced computerized treatment planning systems that incorporate imaging modalities such as CT or MRI to delineate tumor boundaries and adjacent anatomy. These systems support dose distribution optimization, ensure sufficient tumor coverage, and protect critical structures by carefully applying dose-volume constraints and identifying dose-limiting tissues.[11][12][13]

Radiation dosing strategies may involve single-fraction delivery, commonly associated with high-dose-rate brachytherapy, or multiple fractions administered over several treatment sessions, as used in low-dose-rate brachytherapy. Treatment planning requires continuous assessment of therapeutic benefit versus potential toxicity to surrounding tissues. Ultimately, prescribed radiation doses are individualized to each patient’s clinical scenario, with the objectives of maximizing tumor control, preserving normal tissue function, and minimizing adverse effects.

Complications

Brachytherapy is generally considered a safe and effective treatment for skin cancer, but like any medical procedure, it can carry certain risks and complications. Complications of brachytherapy can be categorized as either acute or late toxicity. Dermatitis is a common complication in patients undergoing brachytherapy, particularly in the head and neck. Most commonly, these were reported as being either grade 1 or grade 2.[14] 

The occurrence of grade 3 dermatitis or ulceration represents the second most commonly reported skin toxicity, affecting as many as 50% of patients undergoing brachytherapy in the head, neck, and facial regions.[15][16][17] Changes in skin pigmentation are often cited as the most prevalent late toxicity, with occurrences of grade 1 to 2 hypopigmentation ranging from 5% to 100%. Telangiectasia ranks as the second most frequently reported late toxicity, with its occurrence varying between 5% and 31.4%.[13][15][18][19][20]

Clinical Significance

For skin cancer, brachytherapy is particularly useful when surgical removal may be difficult or cosmetically undesirable, eg, for lesions on the face or ears. Brachytherapy can also be an effective option for treating recurrent tumors or those located in areas where surgery would be challenging. Several nonrandomized studies have demonstrated the efficacy of brachytherapy for treating skin cancer. 

For example, response rates for mold brachytherapy in the treatment of NMSC have been reported as high as 95% in 2 single-institution studies.[16][21] Moreover, the study by Membrive et al evaluated the safety and efficacy of mold brachytherapy over 10 years. Results from this study showed that recurrence rates were as low as 5.7% at a mean follow-up of 96.2 months. Most lesions were situated in the nasal region (80%), followed by the pinna (11.4%), the periorbital area (5.7%), and the cheek (2.9%), albeit with lower frequency. In this study, patients who were medically stable and had no significant barriers to treatment received a total dose of 54 Gy in 3 Gy fractions every other day. Conversely, for frail individuals with potentially restricted mobility, a total dose of 40 Gy was given in 4 Gy fractions per session.[22] Chronic toxicity appeared in 26.6% of patients, but severity was limited to only grade 1 or 2 skin atrophy or induration. 

Interstitial brachytherapy is especially helpful for skin cancers near and around the eye because it allows applicators to be placed within the target, enabling a high dose to be delivered within the clinical target volume without significant damage to vital eye structures while preserving cosmetically sensitive areas.[23][24] Moreover, interstitial brachytherapy may be preferred over mold brachytherapy, especially in areas around the eye, where creating the precise surface mold required for surface-mold brachytherapy may be technically infeasible. Data on interstitial brachytherapy are limited; however, one such study by Cisek et al evaluated its efficacy for NMSC around the eye. Local control throughout the follow-up period was also high, at 97%. During the mean follow-up of 24 months, 7% of patients had a relapse. Another randomized controlled trial compared treatment efficacy and cosmetic outcomes in 174 patients with primary BCC treated with surgery and 173 with radiotherapy. Interstitial low-dose rate brachytherapy with a 57 to 76 Gy total dose delivered over a mean of 6.9 days. Results from this study revealed a 4-year recurrence rate of 0.7% after surgery, compared with 8.8% for those treated with interstitial brachytherapy.[20] Results from these studies are favorable and may be a potential treatment option for NMSC, especially for those situated around or near the eye; however, more high-quality randomized controlled trials are needed to fully elucidate its potential for treating NMSC. 

Enhancing Healthcare Team Outcomes

Overall, brachytherapy offers a valuable treatment option for skin cancer, providing excellent tumor control while preserving cosmesis and minimizing adverse effects. However, treatment decisions should be made in consultation with an interprofessional team of oncologists and surgeons to determine the most appropriate approach for each case. Enhancing patient-centered care, outcomes, safety, and team performance in brachytherapy requires a collaborative effort among various healthcare professionals, including physicians, advanced practitioners, nurses, pharmacists, and others. Physicians and advanced practitioners need expertise in treatment planning, radiation dosimetry, and patient assessment. Nurses require proficiency in patient education, symptom management, and monitoring for treatment-related adverse effects. Developing a comprehensive treatment strategy is essential for successful brachytherapy. This involves interprofessional collaboration to tailor the treatment plan to the individual patient's needs, considering factors such as tumor characteristics, patient comorbidities, and treatment goals. Regular team meetings and case conferences can facilitate strategic planning and ensure alignment among team members.

Ethical considerations in brachytherapy include informed consent, patient autonomy, and respect for patient confidentiality. Healthcare professionals must uphold ethical principles in all aspects of care delivery, ensuring that patients are fully informed about the risks, benefits, and alternatives to brachytherapy. Ethical dilemmas, such as balancing treatment efficacy with potential adverse effects, should be addressed through open communication and shared decision-making. Coordinating care across various healthcare settings and disciplines is critical in brachytherapy. This involves seamless transitions between outpatient clinics, radiation oncology departments, and other healthcare facilities. Care coordination ensures continuity of care, minimizes treatment delays, and optimizes patient outcomes. As a result, dermatologists must work closely with oncologists and radiation oncologists to provide effective, safe brachytherapy for patients with NMSC who are amenable to this treatment modality.