ASTRO Issues Clinical Guideline on Radiation Therapy for Basal Cell and Cutaneous Squamous Cell Carcinomas

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A new clinical guideline from the American Society for Radiation Oncology (ASTRO) provides recommendations on the use of radiation therapy to treat patients diagnosed with the most common types of skin cancers. The guideline details when radiation treatments are appropriate as stand-alone therapy or following surgery for basal cell and cutaneous squamous cell carcinomas, and it suggests dosing and fractionation for these treatments. The guideline was published by Likhacheva et al in Practical Radiation Oncology.

Skin cancer is the most prevalent cancer in the United States, with more than 5 million cases diagnosed each year. More than 95% of these diagnoses are basal cell or cutaneous squamous cell carcinomas, 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 nonmelanoma skin cancers, radiation therapy can play an integral role in both the curative and postoperative settings.

ASTRO developed the new guideline to provide clarity about treatment options. “There is significant variation in practice about when and how radiation should be used for nonmelanoma skin cancers, largely because few randomized studies have compared modern treatment options head-to-head,” explained Phillip Devlin, MD, FASTRO, Chair of the guideline task force and a radiation oncologist at Brigham and Women’s Hospital.

“For this guideline, we drew on the consensus of a multidisciplinary group of leading experts, as well as a systematic review of the evidence, to help physicians understand when radiation is most likely to benefit their patients and to encourage informed discussion about treatment options,” added Anna Likhacheva, MD, MPH, Vice Chair of the guideline task force and a radiation oncologist with Sutter Medical Group in Sacramento.

Recommendations for Radiation Therapy

The guideline first defines appropriate indications for radiation therapy as definitive/curative treatment for basal cell or cutaneous squamous cell carcinoma, as adjuvant treatment following surgery, and as 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 basal cell or cutaneous squamous cell carcinoma who cannot undergo or decline surgical resection. It is conditionally recommended for patients with basal cell or cutaneous squamous cell carcinoma 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/postoperative setting, radiation following surgery is recommended for patients at high risk of cancer recurrence, including a strong recommendation when there is evidence that basal cell or cutaneous squamous cell carcinoma has spread to a patient’s nerves. Postoperative radiation is also recommended for patients at high risk of recurrence following surgical resection, including strong recommendations for high-risk patients with cutaneous squamous cell carcinoma and conditional recommendations for high-risk patients with the relatively less aggressive basal cell carcinoma. Recommendations also outline prognostic features that indicate which patients are at greater risk for recurrence and spread.
  • For patients with basal cell or cutaneous squamous cell carcinoma that has spread to regional lymph nodes, surgical removal of the affected lymph nodes followed by radiation is strongly recommended for both basal cell and cutaneous squamous cell carcinoma, although not for patients with one small involved lymph node without extracapsular spread. The guideline also strongly recommends definitive radiation for patients with regional cutaneous squamous cell carcinoma spread who cannot undergo surgery.

Recommendations 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.

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, and dermatologist; and dermatopathologists. The guideline was developed in collaboration with ASCO and the Society of Surgical Oncology, who provided representatives and peer reviewers.

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