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.