ASTRO issues guidelines on radiation therapy for basal, cutaneous squamous cell carcinoma
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American Society for Radiation Oncology has issued guidelines on the use of radiation therapy in the management of basal and cutaneous squamous cell carcinomas.
“ASTRO felt that there was lack of high-quality evidence on this topic, which made standardization of clinical practice challenging. To the best of our knowledge, no evidence-based clinical practice guidelines, endorsed by a large professional organization, currently exist to provide direction on the use of radiation therapy for these malignancies,” Anna O. Likhacheva, MD, MPH, radiation oncologist in the department of radiation oncology at Sutter Medical Center in California and vice chair of the ASTRO guideline task force, told Healio.
“Our hope is that the oncology community will find the guidelines helpful, especially when it comes to defining clinical and pathologic characteristics that may necessitate a discussion about the merits of definitive and postoperative radiation therapy,” she added.
ASTRO assigned a task force to obtain consensus of a multidisciplinary group of experts and perform a systematic review of literature to develop the guideline recommendations, aimed at helping physicians understand when radiation therapy may benefit patients with basal and cutaneous squamous cell carcinomas and encouraging informed discussions about treatment options.
The guidelines — published in Practical Radiation Oncology — recommended consideration of definitive radiation therapy as a curative option when surgery may compromise function or cosmesis in anatomically sensitive areas, including the ears, nose, lips and eyelids. However, the guidelines discouraged use of the therapy for patients with genetic conditions predisposing them to heightened radiosensitivity, including ataxia telangiectasia, nevoid basal cell carcinoma syndrome or Li-Fraumeni syndrome.
The task force recommended wider use of postoperative radiation therapy for patients with cutaneous squamous cell carcinomas, but not for those with basal cell carcinoma, as cutaneous squamous cell carcinoma tends to be more aggressive in nature and associated with increased risk for regional and nodal spread.
The task force also recommended definitive radiotherapy for clinically or radiographically apparent lymph node metastases ineligible for surgery. However, outcomes may be inferior to that of surgery and adjuvant radiation therapy.
Patients should be selected carefully for lymph node basin radiation therapy due to associated adverse events, such as dermatitis, lymphedema and mucositis, according to the guidelines. Ideal candidates include those receiving adjuvant radiation therapy to a high-risk primary tumor at a site that overlaps a draining lymph node basin.
The task force also recommended careful consideration of radiation doses used as part of lymph node management due to the potential morbidity of treatment. Published data indicated that a dose of 6,000 cGy in 200 fractions is sufficient after therapeutic lymphadenectomy.
Appropriate use of megavoltage electrons, brachytherapy, kilovoltage and megavoltage photons results in similar local control and cosmetic outcome among patients with basal cell carcinoma and cutaneous squamous cell carcinomas, the literature review suggested. Therefore, the task force recommended basing the modality and fractionation scheme upon tumor characteristics and normal tissue considerations.
Further, the task force advised against using hedgehog pathway inhibitors such as vismodegib (Erivedge, Genentech) and sonidegib (Odomzo, Sun Pharma), as well as immunotherapy agents such as cemiplimab (Libtayo, Regeneron), in settings where curative-intent surgery or radiation therapy is feasible.
Systemic therapy is considered an adjunct to the definitive modalities of surgical excision and radiation therapy in clinical scenarios of basal cell carcinoma and cutaneous squamous cell carcinomas at high risk for recurrence. Concurrent platinum-based chemoradiation is well-established in previous research in the setting of advanced mucosal cutaneous squamous cell carcinoma.
Likhacheva and colleagues recommended collection of patient outcomes whenever possible as part of clinical trials and prospective registries to bolster the overall quality of data on the use of radiation therapy in the management of basal cell carcinoma and cutaneous squamous cell carcinoma.
“These guidelines standardize recommendations for the most common clinical scenarios, providing clinical pathways for patient referral to radiation oncology from dermatology and surgical oncology,” Likhacheva told Healio. “We also believe that the detailed description of dose, fractionation and technique will meaningfully inform the daily practice of radiation oncologists when it comes to treating these cutaneous malignancies.” – by Jennifer Southall
For more information:
Anna O. Likhacheva, MD, MPH, can be reached at Sutter Health, 2825 Capitol Ave., Sacramento, CA 95816; email: likhacao@sutterhealth.org.
Disclosures: The authors report no relevant financial disclosures.
Perspective
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Omid Hamid, MD
The ASTRO guidelines for definitive and postoperative radiation therapy for basal and squamous cell cancers of the skin by Likhacheva and colleagues come at a fortuitous time in our care of these patients. Clearly, immune therapeutics such as PD-1 therapy have become standard in the care of patients with cutaneous squamous cell carcinoma in the neoadjuvant and metastatic space, with two randomized trials evaluating the efficacy of this approach in the adjuvant space for high-risk patients. Not far behind is the acceptance of similar approaches for basal cell carcinoma based upon the ongoing trials. Given our lack of options in the past, there has been a lack of conformity toward our approach to these malignancies. With a game plan in place, these clear and concise recommendations provide the ability to compare outcomes across multiple trials and modalities.
The task force utilized a multidisciplinary team, mimicking clinical practice for these intricate patients. Medical, surgical and radiation oncologists collaborated with pathology and dermatology along with involvement from ASCO and Society of Surgical Oncology. The guidelines reaffirm the curative ability of radiation therapy for recurrent patients and those refusing surgery — this point is sometimes lost on practitioners given the rarity of experience. At times, clinical practice may have just meant “anecdotal experience.”
Local recurrence of high-risk basal cell carcinoma and cutaneous squamous cell carcinoma remains a significant problem. The guidelines recommend radiation therapy for close margins, recurrence and deep tumors. It should be noted that the majority of data comes from patients with head and neck sites but are relatable to all cutaneous squamous cell carcinoma and basal cell carcinoma. Importantly, the guidelines argue against the use of chemotherapy concurrent with radiation in the adjuvant setting. Clear indications and definitive doses for treating regional nodes are described for the adjuvant and unresectable patient. The guidelines also cite retrospective data indicating higher regional disease control with adjuvant radiation therapy.
The authors should be lauded for clearly defining the role of radiation therapy in the management of basal cell carcinoma and cutaneous squamous cell carcinoma. This publication allows for future discussion of therapeutic outcome and benefit with all players on the multidisciplinary team speaking the same language.
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