What Is Superficial Radiotherapy and How It Works? Pros and Cons

SRT is often the best choice for early-stage non-melanoma skin cancers like BCC and SCC, particularly when located on sensitive areas such as the face, scalp, eyelids, ears, and nose where minimizing scarring is a priority. It’s also strongly considered for patients who are not suitable candidates for surgery due to health concerns or a fear of surgical procedures. Individuals with multiple skin cancers needing treatment or those specifically seeking a non-surgical approach are also well-suited for SRT. The ability to see the cancer shrink during treatment, especially with image-guided SRT, adds to its appeal.

What Is Superficial Radiotherapy?

Superficial Radiotherapy (SRT) is a non-surgical treatment using low-power X-rays to eliminate skin cancer cells near the surface, similar to dental X-rays. It targets only the outer skin layers, making it useful for non-melanoma cancers like basal and squamous cell carcinoma. SRT’s precision minimizes impact on deeper tissues. Advanced Image-Guided SRT uses ultrasound for better accuracy and to monitor the tumor’s response.

How Does Superficial Radiotherapy Work?

SRT works by aiming a controlled beam of low-energy X-rays at the skin area with cancer or benign conditions. These X-rays penetrate only a few millimeters, damaging the DNA of targeted cells, especially cancer cells, preventing them from multiplying and destroying them. This shallow penetration allows SRT to precisely target surface tumors without harming deeper, healthy tissues and organs. Essentially, SRT delivers a focused radiation dose strong enough to eliminate surface abnormalities while minimizing damage to underlying body structures.

What Are the Main Types of External Radiotherapy?

Superficial radiotherapy primarily uses low-energy X-rays or electron beams to treat surface skin conditions. Low-energy X-rays from a specialized machine penetrate a few millimeters, targeting surface cancers and non-cancerous issues. Electron Beam Therapy, using a modified LINAC, also treats superficial tissues. The choice between these depends on the specific characteristics and depth of the treatment area, as determined by the medical team. The main difference lies in the source of the low-energy radiation: photons from a specific X-ray unit or electrons from a modified LINAC.

What is Image-Guided Superficial Radiotherapy (IG-SRT)?

Image-Guided Superficial Radiotherapy (IG-SRT) enhances standard SRT by adding real-time imaging, often ultrasound. This lets doctors see the cancerous area, precisely determine its size and location before and during treatment. Ultrasound guides the low-dose X-rays to the tumor, minimizing harm to healthy skin. This imaging also allows the medical team to monitor the cancer’s shrinkage, making IG-SRT a more targeted approach for surface skin conditions compared to other radiation treatments.

McClure et al. (2023), in Clinical and Translational Radiation Oncology, found that Image-Guided Superficial Radiation Therapy (IGSRT) for early-stage non-melanoma skin cancers (NMSCs) showed a statistically significantly improved 2-year recurrence probability compared to Mohs micrographic surgery (MMS), with P < 0.001. 1.

What to Expect During Superficial Radiotherapy?

During Superficial Radiotherapy (SRT), expect quick, painless outpatient sessions, around 15 minutes each. You’ll lie or sit comfortably while a specialist delivers low-energy X-rays to the skin. SRT minimizes deep tissue damage, and you can usually return to normal activities immediately with no downtime. The process is often comfortable, sometimes with mild warmth. Treatment length varies, typically involving multiple sessions over several weeks.

What Types of Cancer Are Treated with Superficial Radiotherapy?

SRT effectively treats surface skin cancers, mainly non-melanoma types like basal cell carcinoma (BCC) and squamous cell carcinoma (SCC). Its shallow penetration is ideal for these outer-layer cancers. SRT is especially beneficial for tumors in cosmetically sensitive areas like the face, scalp, neck, ears, and nose because it’s non-surgical, minimizes deep tissue damage, and results in little to no scarring, offering better cosmetic outcomes than surgery. It’s also preferred for patients unsuitable for surgery due to health issues or fear. SRT can also treat Kaposi’s sarcoma and lentigo malignant, making it a valuable option for eradicating superficial cancers while preserving skin appearance.

Harris et al. (2024), in Oncology and Therapy, reviewed Image-Guided Superficial Radiation Therapy (IGSRT), finding it consistently delivers high cure rates (>99%) for early-stage non-melanoma skin cancers (NMSCs), statistically surpassing non-image guided SRT, external beam radiation (XRT), and Mohs micrographic surgery (MMS). IGSRT, combining traditional SRT with high-resolution dermal ultrasound (HRDUS), is becoming a standard first-line therapy for early-stage NMSCs in dermatology clinics.

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Superficial Radiotherapy Side Effects: What Should You Expect?

While Superficial Radiotherapy (SRT) is designed to minimize side effects compared to more invasive treatments, patients may still experience some reactions. The treated skin might become red, irritated, dry, or itchy. Temporary hair loss in the area is also possible. These effects usually go away within a few weeks after treatment ends. Longer-term changes could include slight color changes or increased sun sensitivity in the treated skin. It’s important to discuss potential side effects with your doctor for personalized information.

Published in the 1999 Journal of the American Academy of Dermatology, this retrospective study of 1188 patients (2002 primary malignant epithelial neoplasms) treated with x-ray therapy from 1982-1995 showed a 98.7% complete remission rate, a 90.73% 5-year cure rate, and “good” or “acceptable” cosmetic results in 84.01% of lesions, with low complication rates. The study concludes dermatologic radiotherapy is effective and safe for treating these neoplasms.

Short-Term Side Effects of SRT

During or shortly after undergoing Superficial Radiotherapy (SRT), it is common for patients to observe some temporary changes to the skin in the treated area. These short-term effects can include the development of redness, similar to a mild sunburn, as well as feelings of dryness or a general mild irritation of the skin. These reactions are typically localized to the specific area that received radiation and are a normal response of the skin to the low-energy X-rays used in the therapy.

Song et al. (2024) retrospectively analyzed 21 patients undergoing superficial radiotherapy after non-melanoma skin cancer surgery, finding radiodermatitis as the main adverse reaction, occurring in 7 patients. Radiodermatitis was more prevalent in areas with abundant subcutaneous fat (6 patients) compared to areas with thin subcutaneous fat (1 patient). Dividing the treatment cycle into two stages reduced radiodermatitis incidence (2 out of 12 patients) compared to a single stage (5 out of 9 patients).

To ease short-term skin discomfort after SRT, your doctor may prescribe topical creams. Maintain gentle skin hygiene with unfragranced soap and pat dry. Protect treated skin from direct sun by covering it or using high SPF sunscreen due to increased sensitivity. Following these tips helps manage temporary side effects and supports healing.

Long-Term Side Effects of SRT

Months or even years following Superficial Radiotherapy (SRT), some individuals might observe long-term changes in the treated skin. These potential late effects can include alterations in the skin’s pigmentation, where the treated area might appear slightly paler or darker than the surrounding skin. Additionally, there could be changes in the texture of the skin, although significant textural changes are less common with SRT due to its superficial nature compared to deeper radiation therapies. These long-term effects are generally subtle but are important to be aware of as a possibility after undergoing SRT.

Schulte et al. (2005) reported on 1267 basal and squamous cell carcinomas treated with soft x-ray therapy from 1988-1992, noting a 6.3% late ulceration rate, with 82.5% of those curable conservatively.

To reduce long-term side effects after SRT, attend all follow-up appointments for skin monitoring and early detection. Consistently protect treated skin from the sun with clothing and high SPF sunscreen. Following healthy lifestyle habits recommended by your doctor can also help promote long-term well-being. Adhering to these strategies is important after SRT.

Pros and Cons of Superficial Radiotherapy

SRT’s advantages include being non-invasive (no cutting, anesthesia), often with minimal scarring, especially in cosmetic areas. It typically has no downtime, high cure rates for early non-melanoma skin cancers, and is usually covered by insurance. SRT benefits those fearing surgery, with health risks, needing multiple treatments, or wanting to avoid surgical side effects. Image-Guided SRT allows tracking progress.

However, SRT also has drawbacks. It is primarily recommended for non-melanoma skin cancers in the early stages because it may be less effective for later stages or melanoma, which can spread to deeper tissues. While generally well-tolerated, potential side effects include skin irritation, redness, thinning, and a slightly increased risk of infection in the treated area. Rare side effects like skin ulcers can also occur.

source: www.foradermatology.com

Who Is a Good Candidate for Superficial Radiotherapy?

SRT is often the preferred treatment for individuals with early-stage non-melanoma skin cancers, such as basal cell carcinoma and squamous cell carcinoma. Its suitability is particularly high when these cancers are located in cosmetically sensitive areas like the face, scalp, eyelids, ears, and nose, as SRT aims to minimize scarring. Moreover, SRT is a strong option for patients who cannot undergo surgery due to underlying health conditions or a fear of surgical procedures. Individuals with multiple skin cancers requiring treatment or those specifically seeking a non-surgical approach are also excellent candidates. The ability to monitor the treatment’s effectiveness through visible shrinkage of the cancer, especially with image-guided SRT, further enhances its appeal for these patients.

What Are the Signs Superficial Radiotherapy Is Working?

Effectiveness of Superficial Radiotherapy (SRT) is often indicated by noticeable changes in the treated area over time. A primary sign is the visible shrinking of the tumor, as the radiation works to destroy the cancerous cells. Additionally, the healing process of the treated skin is a positive indication; while some initial reactions like redness or irritation might occur, their eventual fading, along with the disappearance of the tumor, suggests the therapy is successful. If the skin cancer initially presented with symptoms such as discomfort or an unusual texture, the improvement or complete resolution of these symptoms is another sign that SRT is having the desired effect.

Comparison: Superficial Radiotherapy vs. Traditional Treatments

Superficial Radiotherapy (SRT) is comparable in effectiveness to surgery and cryotherapy for early non-melanoma skin cancers. Surgery physically removes the cancer but can cause scarring and requires recovery. Cryotherapy freezes the lesion but can also scar and have less precise depth control than SRT. SRT is non-invasive, using radiation to destroy cancer cells with minimal to no scarring and no downtime, making it ideal for cosmetic areas. Patient preference often leans towards SRT for its convenience and cosmetic benefits, especially for those avoiding surgery or with concerns about scarring. However, surgery offers immediate tissue removal, which some patients prefer. The best choice depends on the cancer’s specifics, location, and individual patient needs and desires.

Recovery of the Body After Superficial Radiotherapy

Recovery after SRT is usually easy, as it’s non-invasive with no bleeding, wounds, or major scarring. 1 Most patients can resume daily activities right away. 2 However, good skin care in the treated area is key. Protect it from direct sun with cover or high SPF. 3 Use gentle, unfragranced soap and moisturizers, and pat dry. 4 While generally no activity limits, avoid swimming during treatment and for a bit after. 5 Contact your doctor for unusual or severe skin reactions like significant pain, blisters, infection signs (more redness, swelling, pus), or a non-healing ulcer. Always follow your radiotherapy team’s aftercare advice and report any concerns.

Written by Aren Karapetyan, MD