Mohs Micrographic Surgery: AAD Guidelines on Superficial Radiation and Brachytherapy

Issues of Concern

Superficial radiation therapy is commonly used to treat nonmelanoma skin cancers, such as basal cell carcinoma and squamous cell carcinoma in situ, due to its ability to target cancerous cells while sparing healthy tissue. This therapy may also be used on keloids. Although superficial radiation therapy may be used in certain melanoma cases, it is not the primary treatment modality for this condition. Superficial radiation therapy should not be used in patients with certain tumors, such as verrucous carcinoma, as it can induce anaplastic transformation of the lesion. Superficial radiation therapy and brachytherapy are generally well-tolerated treatment modalities for skin cancer, but like any medical intervention, they carry potential adverse events and safety concerns. Adverse events associated with superficial radiation therapy may include acute skin reactions such as erythema, edema, and desquamation, which are typically mild and self-limiting. However, in some cases, patients may experience more severe reactions such as ulceration, necrosis, or fibrosis, particularly with higher radiation doses. Long-term adverse effects of superficial radiation therapy may include hypopigmentation or hyperpigmentation of the skin, and the rare possibility of secondary malignancies, although the risk is generally low. To optimize therapeutic efficacy while minimizing complications, healthcare providers must carefully monitor patients undergoing superficial radiation therapy and adjust treatment parameters as needed.[1] Radiation therapy is strictly contraindicated in genetic syndromes that increase susceptibility to radiation-related injury, such as Gorlin syndrome and xeroderma pigmentosum. Radiation exposure can lead to cataract formation, as the radiobiological effectiveness of neutrons and heavy ions can be greater than 50 for a small absorbed dose.

Similarly, brachytherapy, which involves the insertion of radioactive sources directly into or near the tumor site, carries its own set of safety considerations. Common adverse events associated with brachytherapy for skin cancer include localized skin reactions such as erythema, edema, and dermatitis at the treatment site. In some cases, patients may also experience pain or discomfort at the insertion site of the radioactive sources. In addition, there is a risk of radiation exposure to healthcare providers during the placement and removal of brachytherapy devices, necessitating careful adherence to safety protocols and radiation protection measures. Despite these potential adverse events, brachytherapy is generally considered a safe and effective treatment option for skin cancer, particularly for lesions in cosmetically sensitive areas or for patients who are not candidates for surgery.[2]

Clinical Significance

The standard treatment for nonmelanoma skin cancer is local destruction or surgical excision. Destructive and invasive methods include electrodesiccation and curettage, elliptical excision, or Mohs micrographic surgery. In some cases where a tumor is superficial or small and well-defined, photodynamic therapy, topical therapies, or cryosurgery may serve as adequate treatment options. Topical therapies include imiquimod, which is used alone, and 5-fluorouracil, which can be used either alone or in combination with calcipotriene. There are various types of energy-based therapies, which include superficial radiation therapy and brachytherapy. The utilization of radiation therapy in skin cancer treatment experienced an initial decline following the advent of Mohs micrographic surgery; however, in more recent years, it has garnered increased favorability.[3] These treatment modalities are suitable for large or small tumors, especially in challenging locations or when a patient cannot undergo a surgical procedure. The choice of treatment depends on factors such as the patient's age, patient-specific comorbidities, patient quality of life, and the type and location of the tumor. If a tumor is located in an area where cosmetic or functional consequences may occur, noninvasive methods such as superficial radiation therapy and brachytherapy should be considered. Importantly, radiation therapy can serve as an adjuvant treatment after surgical excision or Mohs micrographic surgery to minimize the risk of local or regional recurrence in high-risk cases. Radiation therapy is typically recommended when recurrence risk is elevated or when successful salvage surgery is unlikely, particularly in the presence of factors such as perineural invasion, large tumor size, or positive surgical margins. Adjuvant radiation is also indicated for tumors with close margins that cannot be fully re-excised or for recurrent disease following previous treatments.[1]

Superficial radiation therapy is a noninvasive medical procedure that uses x-rays or photons to emit electromagnetic energy to the skin's surface. This energy targets rapidly dividing cells, such as those observed in malignant processes. When targeting these cells, the energy emitted halts mitosis, resulting in cell death. Dosing is based on the unit known as a Gray (Gy), and the dose delivered in a single treatment session is known as the fraction.[4] Unlike traditional radiation therapy techniques, which emit higher energy, superficial radiation therapy delivers low-energy radiation from 50 to 150 kVp.[3] The energy level also affects the depth of penetration. Traditional radiation therapy uses higher energy, resulting in deeper tissue penetration. The advantage of superficial radiation therapy for cutaneous malignancies lies in its limited penetration depth, which preserves underlying structures while effectively delivering therapeutic doses to the affected skin. The mechanism of superficial radiation therapy enables its use in treating various skin conditions, mainly superficial skin cancers such as basal cell carcinoma and squamous cell carcinoma. This approach is particularly advantageous for lesions located on cosmetically sensitive areas, as it typically results in minimal scarring and preserves the aesthetic appearance of the treated area. The most suitable areas for treatment with superficial radiation therapy include the face (perioral, periorbital, nasal alar rim, ear, and scalp) and the lower extremities, such as the knees.[5] Superficial radiation therapy is typically administered in multiple sessions over several weeks, allowing for precise dosage control and optimization of treatment outcomes. Superficial radiation therapy offers patients a relatively quick, convenient, and effective alternative to surgical interventions for superficial skin malignancies. In addition, radiologic oncology guidelines emphasize the efficacy of superficial radiation therapy in achieving high cure rates while preserving cosmesis and functional outcomes, making it a favorable option for older patients or those with comorbidities who may be poor candidates for surgery.

Brachytherapy offers another valuable therapeutic avenue in treating nonmelanoma skin cancer. This therapy is a specialized form of radiation therapy that is characterized by the precise placement of radioactive sources directly into or near the tumor site, using the energy of radioisotope decay.[6] Unlike external beam radiation therapy, which delivers radiation from a source at a distance outside the body, brachytherapy delivers a highly concentrated dose of radiation directly to the tumor through a radioactive source applied on the treatment area, such as a surface mold, or through an interstitial radioactive source placed within the body.[2] When the radioactive source is interstitial, it may be delivered as either permanent implants or temporary implants, depending on the specific treatment plan and cancer type. Brachytherapy offers several advantages, including precise targeting of the tumor, reduced risk of radiation exposure to nearby organs, and shorter treatment durations compared to external radiation therapy. The National Comprehensive Cancer Network guidelines underscore the efficacy of brachytherapy, particularly in treating tumors of the head and neck region, where surgical excision may be challenging due to functional or cosmetic concerns. Furthermore, brachytherapy is a preferred option for patients with multiple lesions or those requiring re-irradiation, offering a well-tolerated and effective alternative to surgery.[7]

Superficial radiation therapy and brachytherapy are most effective for treating superficial tumors (not exceeding 2 mm in depth), less than 2 cm in diameter, and well-circumscribed.[2] Good candidates for superficial radiation therapy and brachytherapy may be patients who cannot tolerate a lengthy surgical procedure or treatment regimen or are at high risk for surgical complications due to multiple comorbidities and anticoagulant use.[8] These treatment modalities offer good cosmesis, minimal toxicity, and local control, making them good options for treating nonmelanoma skin cancer.[9][10] The average local recurrence rates for treating cutaneous squamous cell carcinoma with superficial radiation therapy and brachytherapy are 6.4% and 5.2%, respectively.[11] Average recurrence rates with the use of superficial radiation therapy for treating basal cell carcinoma have been reported to be 4.2%.[5] Superficial radiation therapy and brachytherapy have established protocols and consensus guidelines to ensure optimal treatment outcomes and patient safety.[3][5] These guidelines encompass various aspects of patient care, including appropriate patient selection, treatment planning, radiation dose optimization, tumor size, subtype, location, and follow-up monitoring. Superficial radiation therapy and brachytherapy are promising options in treating nonmelanoma skin cancer when used appropriately. Therefore, adherence to these guidelines is paramount in achieving favorable clinical outcomes and minimizing treatment-related morbidity in treating nonmelanoma skin cancer.

Notably, the American Academy of Dermatology (AAD) emphasizes that surgical treatment remains the most effective option for basal cell carcinoma and squamous cell carcinoma. Although superficial radiation therapy and brachytherapy can be considered as secondary treatments in cases where surgery is not viable, they should only be pursued after discussing the potential benefits and risks with patients. The AAD also underscores the need for further research into the long-term outcomes of these therapies and highlights the importance of dermatologists to comply with varying federal and state regulations regarding their use. In addition, practices should prioritize patient care over financial gain to maintain ethical standards and avoid scrutiny from regulatory bodies. Finally, accurate coding for these services must be confirmed by reliable sources to ensure appropriate reimbursement and prevent access restrictions.

Nursing, Allied Health, and Interprofessional Team Interventions

Superficial radiation therapy and brachytherapy for skin cancer can involve a multidisciplinary team, including dermatologists, pathologists, medical oncologists, surgeons, and radiation oncologists.[12] In addition, physician assistants, nurse practitioners, nurses, radiation technicians, and medical assistants are crucial in radiation therapy. Each healthcare professional involved must possess specialized skills related to their respective roles. Clinicians and advanced practitioners must possess expertise in diagnosing skin cancer, developing appropriate treatment plans, determining appropriate radiation dosing schedules, and administering radiation therapy safely and effectively. Nurses play a crucial role in patient education, monitoring treatment sessions, monitoring for treatment-related adverse effects, and providing supportive care. Pharmacists ensure accurate medication management, including the prescription of pain medications and the management of potential drug interactions.

Interdisciplinary meetings should be held regularly between the primary treating clinician and the treatment team to discuss patient cases, review treatment plans, and address any challenges or concerns. In each visit, a review of the patient's progression through treatment should be discussed. A strategic approach also involves considering alternative treatment options and optimizing resources to achieve the best possible outcomes for patients.

Clinicians must involve patients in decision-making, ensuring they understand the risks, benefits, and alternatives of superficial radiation therapy and brachytherapy. Patients should be informed about potential early treatment effects such as dermatitis, erythema, edema, and pain.[13] Later effects such as depigmentation, telangiectasia, and potential ulceration should be reviewed.[13] Alternative treatment options, including topical creams, photodynamic therapy, cryosurgery, electrodesiccation and curettage, surgical excision, and Mohs micrographic surgery, should be discussed.[14][15] These alternatives should be presented in the context of the tumor type and behavior, providing patients with a comprehensive understanding to aid in their decision-making process.

Effective communication among team members is crucial for seamless coordination of care and error prevention. Clear and concise communication facilitates the exchange of treatment information, enhances understanding of patient-specific treatment plans, and fosters collaboration. Care coordination includes coordinating appointments, scheduling treatment sessions, and facilitating communication between different providers involved in the patient's care. These efforts aim to minimize treatment delays, reduce unnecessary duplication of services, and improve the overall patient experience in patients undergoing superficial radiation therapy or brachytherapy for nonmelanoma skin cancer.