By Renata Prado, MD

What is Skin Cancer?

Skin cancer is the most prevalent cancer type in the United States with an incidence rate of over 5 million cases annually¹. There are more skin cancers diagnosed in a year than all other cancers combined. The two most common types are called basal cell carcinoma (BCC) and cutaneous squamous cell carcinoma (cSCC) and together, they account for over 95% of all skin cancer diagnoses².

How to Choose a Skin Cancer Treatment

When a patient is diagnosed with skin cancer, the doctor will take several factors into account to make a decision on the best treatment. The first thing we look at is the skin cancer type (for instance, it is a basal cell carcinoma or a melanoma?), as well as its histological subtype (for instance, is this a superficial BCC or an infiltrative BCC?). The type and histological subtype of a skin cancer is information provided by the pathologist after a biopsy of a skin cancer. To make the decision about the treatment, your dermatologist is also considering the skin cancer size and its location. An invasive cancer on the eyelid may need a different treatment than a superficial cancer on the back. Knowing the cancer type and subtype, the location and size of the cancer, and taking into account any additional medical or personal information specific of the patient, including personal preferences, the dermatologist will then recommend the best treatment for the skin cancer.

Skin Cancer Treatment Options

Treatment options are varied, and include topical agents (a cream), “freezing it” (cryotherapy), “scraping and burning it” (electrodesiccation and curettage), or “cutting it out” (removing it surgically via surgical excision or Mohs Micrographic Surgery). Chemotherapy and immunotherapy are medications given in specific cases, usually more aggressive or advanced cancers that have spread to other parts of the body.  In select cases, radiation therapy can be considered, either as an adjuvant (when it is given after surgery has removed the cancer to avoid recurrence) or as the primary treatment for the cancer.

Mohs Micrographic Surgery for the Treatment of Skin Cancer

For skin cancers on the face, the first line of treatment and gold standard is Mohs Micrographic Surgery. Mohs has the highest cure rate for treatment of skin cancer mainly because the removed tissue is microscopically examined immediately after the removal, with 100% of the surgical margins being examined. It is also considered a tissue sparing technique, meaning, it only removes the minimal amount of normal tissue to obtain clear margins.

Mohs is done in the office under local anesthesia. Briefly, the area is cleaned and numbed, the skin cancer is removed with a small rim of normal skin around it, and the tissue is taken to the Mohs lab. A temporary dressing is placed on the area, and the patient waits for the tissue to be processed and analyzed. The Mohs surgeon will then look at the tissue under the microscope and evaluate 100% of the margins. If the margins are negative, that means that the cancer has been fully removed. If they are positive, additional tissue is removed at the exact location where it is, because the process is microscopically guided. This allows us to minimize the amount of healthy tissue lost and maximize the functional and cosmetic outcome resulting from surgery. The repair, which involves stitching, is done on the same day.

Because of the meticulous Mohs technique, it gives the highest cure rate of any skin cancer treatment: 99% cure rate. It is done in one day, and most patients tolerate it very well. Discomfort after the procedure is managed in most cases with Tylenol and Ibuprofen in the first 24-48 hours. There may be swelling and bruising for one week, at which point, patients may resume physical activities. Most patients feel very satisfied with the treatment and the resulting cosmetic outcome. Because it is a surgical procedure, it carries risks, such as bleeding, infection, opening of the stitches or hematomas. These complications are reported in about 1% of cases.

Radiation Therapy for the Treatment of Skin Cancer

Recently, a lot of attention has been given to superficial radiation therapy (SRT), which has been advertised as an alternative to Mohs. It has a great proposition: painless, scar free treatment of skin cancer. Can it be the next great thing? If it is, why is it not recommended as first line treatment by the guidelines of the American Academy of Dermatology (AAD) or the National Comprehensive Cancer Network (NCCN)? These guidelines recommend Mohs or surgery as first line treatment for skin cancers, with radiation being recommended only for patients who are considered “not surgical candidates” or who refuse surgery.

It is important to make two observations here. First, there are several types of radiation treatment, such as superficial radiation therapy, external beam radiotherapy and brachytherapy. There are also several treatment protocols for the same radiation modality, where the amount of radiation, the number of doses and the frequency are different. Second, it is also important to mention that our current skin cancer guidelines see the value of radiation therapy as adjuvant in specific situations. For instance, radiation therapy is considered after surgery when the tumor involves large nerves, even if the surgery removed the cancer with negative margins. Also, for high-risk non-melanoma skin cancers that have undergone multiple resections, and further surgery is not feasible, radiation therapy is recommended as part of multidisciplinary consultation if residual disease is present.³ These are indications for adjuvant radiation therapy, and it is not what we are discussing here. Here, we are discussing the use of radiation as the primary and only treatment modality of skin cancer, in place of surgery. Mainly, we are asking the question: “should I have this skin cancer on my face cut out or treated with radiation therapy?”

Mohs Micrographic Surgery vs. Radiation Therapy for Skin Cancer Treatment

To make medical decisions or recommendation guidelines, the medical community relies on scientific data. Several studies tried to answer this question. The next bullet-points summarize some of the data available, which includes superficial radiation therapy (SRT) and other modalities of radiation therapy^3,4:

• Two meta-analyses reported 5-year recurrence rates of 8.7% and 9.8% after radiation therapy on primary and recurrent BCC, respectively.^5,6
• Retrospective analyses of BCC treated with radiation therapy have reported 5-year local control, cure, or complete response rates ranging from 93% to 96%,^7,8,9 and 5-year recurrence rates from 4% to 16%.^10,11,12
• Efficacy of radiation therapy was better for BCCs that were less advanced, primary (vs. recurrent), or had smaller diameter or nodular histologic subtype.^{7,8, 10, 11, 13}
• A prospective study randomizing 347 patients to receive either surgery (standard excision with free margins ≥2 mm from visible borders) or radiation therapy as primary treatment of BCC reported higher recurrence rates with radiation than surgery (7.5% vs. 0.7%),¹⁴ poorer cosmetic outcomes, and more postoperative complications.¹⁵
• A small number of prospective studies have reported high rates of tumor control with specific radiation dose fractionation regimens for small BCCs.^{14, 16, 17}
• A systematic review and meta-analysis of 21 studies (9729 skin BCC/SCC patients) with post-treatment cosmesis as primary endpoint reported that hypofractionated radiation therapy regimens (external beam RT(n = 9255) or brachytherapy (n = 474)) were associated with favorable cosmetic outcomes. The investigators observed that the median 1-year local recurrence rate was 2% and the 5-year local recurrence rate was 14% when combining all fractionation regimens.¹⁸
• A single-institution 22-year retrospective analysis of non-melanoma skin cancers on elderly patients demonstrated 2, 5, and 10-year tumor recurrence rates of 2.2%, 6.0%, and 10.5% with hypofractionated superficial radiation therapy.¹⁹
• A retrospective chart analysis showed that when patients are highly selected, long-term superficial radiation therapy cure rates up to 98% can be achieved.²⁰

A few points to consider when evaluating studies on radiation:

• The cure rate means that the cancer is no longer there. For Mohs Micrographic Surgery, this is confirmed histologically by looking at margins under the microscope. For patients treated with radiation, diagnosis of cure is based on clinical exam or ultrasound, both of which could miss subclinical disease, and therefore these studies could be underreporting failure to cure.
• Some skin cancers are slow growing and therefore a long follow up is needed to be able to determine definitive cure, or lack of recurrence. Mohs is a well stablished treatment with multiple 5 and 10-year follow up studies confirming its low recurrence rates. Most superficial radiation therapy studies only show short term results (< 3 years), and papers that show long term follow up (~10 years), even in highly selected patient population, show a recurrence rate of 10%.¹⁹
• Secondary cancers (cancers caused by the radiation itself) have a latency of onset of 10 years or longer after radiation therapy. Unfortunately, the published literature does not include greater than 10-year follow up after current SRT dosing regimens, therefore, long-term sequelae of SRT are unknown or unpublished.

All current published studies have limitations. The “perfect study” would have two large and similar groups of patients with similar skin cancers. Each group would receive a different treatment (in this case, surgery vs. radiation), and then we would follow those patients for greater than 10 years and see which group did better. We need to ask questions such as cure rates for each group, recurrences, complications, cosmetic outcomes, how patients felt about the treatment, and even total cost.

Skin Cancer Recurrence After Radiation Therapy

Unfortunately, this “perfect study” has not been yet done, but the current available data, shows a lower cure rate for radiation than surgery, and therefore, surgery is still considered the gold standard and first line treatment. Radiation is not recommended by any of our medical societies or guidelines as first line treatment and is only recommended for non-surgical candidates or patients who refuse surgery. The main reason is that these studies showed that even highly selected cancers (small, more superficial, older patients) still have a much higher chance of recurrence with radiation vs. with Mohs.

Having a recurrence after radiation is an important issue and its implications are not often discussed in the literature. Recurrent cancer cannot be treated with more radiation. Surgery then becomes the only treatment option, which now carries a decreased cure rate (Mohs cure rate is lower for recurrent cancer than for primary cancer, likely due to the possibility of multifocal areas of cancer, or “skip” areas), and difficult healing (as radiated skin will not heal normally).

Other Potential Effects of Radiation Therapy for Skin Cancer Treatment

A few other things to consider about radiation therapy:

• Often, radiation is advertised as a “scar free treatment”. It is important that patients know that radiation is not without changes to the skin. Adverse reactions included hypopigmentation (patches that are lighter in color than the surrounding skin), telangiectasias (small blood vessels that are visible on the skin), desquamation, ulceration, dermatitis, dryness, and permanent local alopecia (hair loss). In younger patients, long term cosmesis should be discussed, as the radiated skin may look worse with time.
• Secondary malignancy (a cancer caused by radiation) is negligible using appropriate radiation doses but needs to be considered in younger patients, for whom a larger lifetime risk of developing secondary malignancy in the treatment field is expected. Generally, radiation is discouraged in patients younger than 60 years old.
• Radiation is contra indicated in patients with genetic conditions that result in heightened radiosensitivity, such as ataxia telangiectasia, nevoid basal cell carcinoma syndrome (Gorlin syndrome), or LiFraumeni syndrome. Poorly controlled connective tissue disorders (like scleroderma), as well as Ehlers-Danlos Syndrome, Mixed Connective Tissue Disease, Systemic Lupus Erythematosus are a relative contraindication to treatment.
• Radiation therapy also requires multiple visits. It is often performed in 15-20 sections over several days or weeks. This should be taken into account as this may not be feasible for some patients. Since this treatment requires multiple visits, the cost of the treatment is also high.

When to Use Radiation Therapy for Skin Cancer Treatment

As with all alternative or second line treatments, there are specific, well selected circumstances in which radiation therapy may be the best option for a given patient. Some patients are very poor surgical candidates because of advanced age, being frail and medically unstable, having dementia, or simply because they are categorically refused to have surgery. In these instances, SRT as a second-choice alternative should be considered.²¹ If an otherwise healthy patient is considering having SRT due to desire to avoid surgery, a higher success rate with this treatment will be with small, low-risk tumors, superficial tumors and elderly patients. Therefore, careful patient selection is important to achieve good outcomes.

Conclusion

Any new treatment for skin cancers that could avoid surgery and still deliver the same high cure rate, excellent safety profile²³ and great outcome is desired and welcomed. For most patients, at least at this moment, it does not seem that radiation is this treatment. It is, however, the best option for a selected patient population, including poor surgical candidates and for patients that surgery will be a devastating emotional experience. Therefore, it is important that dermatologists and Mohs surgeons are knowledgeable about this treatment and recommend it for the appropriate patient. In medicine, there is not “one size fits all”, and it is our role as doctors advocate for our patients, and to treat each one individually.

In conclusion, surgery is a first line treatment for skin cancers due to its high cure rate, excellent safety profile and outcome. Recurrence is the main concern with radiation therapy. However, in a highly selected patient population, including poor surgical candidates, patients with small, low-risk tumors and superficial tumors, elderly patients and patients who refuse surgery, radiation therapy may be an important tool in our treatment armamentarium. Patients should be counseled thoroughly on the benefits and risks of undergoing radiation for the treatment of NMSCs, including risk of recurrence, prolonged treatment course, and side effects.²

Schedule a Skin Exam at Vanguard Skin Specialists Today

At Vanguard Skin Specialists, we have over twenty dermatology professionals who are passionate about skin cancer prevention and detection. Skin cancer is extremely common, but highly treatable. Our providers often say that early detection leads to early treatment which leads to higher cure rates. If you have not had a skin check in the last year, we highly encourage you to call our office at 719-355-1585 or request an appointment online today.

Dr. Renata Prado is a board certified dermatologist and Mohs surgeon. She specializes in the diagnosis and treatment of skin cancer. Dr. Prado trained in her home country of Brazil, Northwestern University, and the University of Colorado-Denver. She is one of Vanguard’s physician leaders, keeping Vanguard focused on our mission of making a positive impact on our patients, our community, and our world.

 

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References:

1. The Surgeon General’s Call to Action to Prevent Skin Cancer. In: (US) OotSG, ed. The Surgeon General’s Call to Action to Prevent Skin Cancer. Washington (DC): US Department of Health and Human Services; 2014.
2. Definitive and Postoperative Radiation Therapy for Basal and Squamous Cell Cancers of the Skin: An ASTRO Clinical Practice Guideline Anna Likhacheva, MD, MPH, Musaddiq Awan, MD, Christopher A. Barker, MD, Ajay Bhatnagar, MD, Lisa Bradfield, Mary Sue Brady, MD, Ivan Buzurovic, PhD, Jessica L. Geiger, MD, Upendra Parvathaneni, MBBS, Sandra Zaky, MD, and Phillip M. Devlin, MD. Practical Radiation Oncology (2019)
3. NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines®) Basal Cell Skin Cancer. Version 3.2024 — March 1, 2024
4. NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines®) Squamous Cell Skin Cancer. Version 1.2024 — November 9, 2023
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