The new ASTRO clinical practice guideline provides recommendations on the use of radiation therapy to treat patients diagnosed with the most common types of skin cancers
By Phillip M. Devlin, MD, FASTRO, and Anna Likhacheva, MD, PhD
Skin cancer is the most prevalent cancer in the United States, with more than five million cases diagnosed each year. More than 95% of these diagnoses are basal and cutaneous squamous cell carcinomas (BCC, cSCC), which, in contrast to melanomas, respond well to radiation therapy if treated promptly and properly. Although surgery to remove the lesion is considered the primary approach for definitive/curative treatment of these non-melanoma skin cancers, radiation therapy can play an integral role in both the curative and post-operative settings.
ASTRO's first guideline for skin cancer was published on December 9, 2019 in Practical Radiation Oncology. The guideline details when radiation treatments are appropriate as stand-alone therapy or following surgery for BCC or cSCC, and it suggests dosing and fractionation for these treatments. ASTRO developed the guideline to provide clarity about treatment options since there is wide variation in practice about when and how radiation should be used for non-melanoma skin cancers, largely because few randomized studies have compared modern treatment options head-to-head.
The guideline was based on a systematic literature review which produced more than 1,500 articles, of which 143 (published from May 1988 through June 2018) were then carefully evaluated. The task force included a multidisciplinary team of radiation, medical and surgical oncologists, a radiation oncology resident, medical physicist, dermatologists and dermatopathologists.
The guideline first defines appropriate indications for radiation therapy as the following: definitive/curative treatment for BCC and cSCC; adjuvant treatment following surgery; and definitive or adjuvant treatment for disease that has spread to a patient's regional lymph nodes.
Recommendations are as follows:
- In the definitive/curative setting, radiation is strongly recommended for patients with BCC or cSCC who cannot undergo or decline surgical resection. It is conditionally recommended for patients with BCC or cSCC located in anatomically sensitive areas such as the nose or lips, where surgery could compromise function or cosmetic outcomes. Definitive radiation therapy is discouraged, however, for patients with genetic conditions that predispose them to be more sensitive to radiation.
- In the adjuvant/post-operative setting, radiation following surgery is recommended for patients at high risk of cancer recurrence, including a strong recommendation when there is evidence that BCC or cSCC has spread to a patient's nerves. Post-operative radiation is also recommended for patients at high risk of recurrence following surgical resection, including strong recommendations for high-risk patients with cSCC and conditional recommendations for high-risk patients with the relatively less aggressive BCC. Recommendations also outline prognostic features that indicate which patients are at greater risk for recurrence and spread.
- For patients with BCC or cSCC that has spread to regional lymph nodes, surgical removal of the affected lymph nodes followed by radiation is strongly recommended for both BCC and cSCC, although not for patients with one small involved lymph node without extracapsular spread. The guideline also strongly recommends definitive radiation for patients with regional cSCC spread who cannot undergo surgery.
The guidelines also address technical aspects of radiation therapy, suggest dosing and fractionation schedules and include a brief discussion of the different types of radiation delivery methods.
The task force concluded that the appropriate use of any of the major radiation modalities results in similar cancer control and cosmetic outcomes. The guideline also considers the use of drug therapies such as chemotherapy, biologic and immunotherapy agents in combination with radiation.
Read the executive summary of Definitive and Postoperative Radiation Therapy for Basal and Squamous Cell Cancers of the Skin: An ASTRO Clinical Practice Guideline and the full-text of the guideline in PRO.
Phillip Devlin, MD, FASTRO, is a world renowned brachytherapist practicing medicine at Harvard Medical School. He is the author of two acclaimed textbooks and scores of academic articles regarding the development of brachytherapy and skin applications. He serves as chair of the task force that developed the guideline.
Anna Likhacheva, MD, is an internationally recognized radiation oncologist and brachytherapist who leads the teaching effort for ABS/ASTRO in the area of brachytherapy and skin cancer. She currently practices radiation oncology at Sutter Medical Center in Sacramento, California, and serves as vice-chair of the task force that developed the guideline.
By Daniel Spratt, MD, and Timur Mitin, MD, PhD
Prostate cancer is diagnosed in more than one million men worldwide each year. In countries with PSA screening, over 90% of cases are diagnosed when they are localized. The two most common treatments are radiation therapy and surgical removal of the prostate. One of the reasons men select surgery is the logistical barrier to undergo radiation therapy for eight to 10 weeks of daily, low-dose radiation therapy treatments (39 to 48 treatments). This can be a huge barrier for patients, especially those who are working, live a distance away, or have financial barriers to commute that often.
Fortunately, technology has improved over the past 30 years, and now there is increasing high-level evidence and guideline support to treat prostate cancer with many fewer treatments. This form of radiation therapy is often termed ultra or extreme hypofractionation, simply meaning fewer fractions of radiation therapy. More than 40 clinical trials have been published on this newer form of radiation therapy, including two large randomized trials. Nearly all the trials have used between four and seven fractions of radiation therapy, with the most common regimen being just five treatments. This is commonly termed stereotactic body radiation therapy (SBRT) or stereotactic ablative body radiotherapy (SABR).
To summarize the evidence of the >6,500 men who have been treated on trials using SABR, grade ≥3 toxicity is typically 0-2%, even with long-term follow-up, and appears to have equal or potentially superior tumor control when compared to conventional radiation therapy. Patients do not require anesthesia or any invasive procedure, as required with surgery or brachytherapy, and the logistical burden is minimal with just five outpatient treatment visits. Additionally, it costs less money to deliver SABR than conventional radiation therapy, uses less resources for departments, and is substantially more convenient for patients. For this reason, SABR is now considered “a” standard of care in National Comprehensive Cancer Network (NCCN) guidelines and used routinely in countries like the United States and Canada at centers capable of delivering the treatment. Recent estimates show 15-20% of patients who are treated with external beam radiation therapy receive it as SABR in the U.S.
Financial considerations unquestionably influence practice patterns, and radiation oncology is no exception. Historically, hypofractionation has been met with lukewarm enthusiasm among practices that bill per fraction. However, in the era of bundled payments that is rapidly approaching, fewer fractions may become more profitable as clinics will be able to treat a greater number of patients or reduce resource utilization. SBRT today in the U.S. is defined by insurance companies as a radiation treatment course with five or fewer fractions. Giving six fractions of the same radiation therapy plan means that the SBRT billing code no longer can be used, even if every single other aspect of the treatment was identical. Thus, six and seven fractions pays less than five fractions because of arbitrary billing code nomenclature. Next year, many centers will receive a set amount of reimbursement for a treatment course, no matter what the treatment is called. Widmark et al. have established a seven-fractions course of EBRT for men with both intermediate and high-risk prostate cancer as non-inferior to conventionally fractionated EBRT, with no rectal spacers and largely with 3-D planning. This regimen may indeed be the most cost-effective randomized trial-proven prostate-directed radiation therapy option for clinics to consider in the era of bundled payment.
We are all patiently waiting for the maturation and completion of Phase III trials, such as PACE-B and NRG GU005, respectively. If the results of these trials demonstrate similar efficacy and toxicity of SABR compared to older forms of radiation therapy at ≥5-years of follow-up, SABR will likely be deemed “the” standard of care for the treatment of localized prostate cancer. Other ongoing areas of investigation include the role of SABR for men with high-risk disease, and promising prospective data has been published from multiple groups demonstrating the safety and efficacy of this approach, even with simultaneous treatment of the pelvic lymph nodes. Finally, in Europe they are comparing SABR head-to-head to surgery. This will be a very informative trial to determine the difference in side effects and quality of life with modern non-invasive SABR compared to surgery.
The bottom-line: Prostate SBRT is here, and we anticipate it will only become increasingly utilized in the U.S. given the convergence of prospective and new level one evidence and financial incentives from the new bundled payment model. We anticipate that learning to safely deliver prostate SBRT will become very important in the not too distant future.
Daniel Spratt, MD, is an associate professor, Laurie Snow Endowed professor, associate chair for Research, and chair of the Genitourinary Clinical Research Division at the Rogel Cancer Center at University of Michigan.
Timur Mitin, MD, PhD, is an associate professor at Oregon Health and Science University. Dr. Mitin co-authored a recently published Red Journal article, SBRT for Localized Prostate Cancer: Is it Ready for Take-Off? on which this blogpost is based.