When treating with adjuvant radiation to the neck after dissection for a nodal recurrence from a nonmelanoma cutaneous malignancy, would you include the primary tumor resection bed in the field if some time has passed since the primary resection?

Would you always/never include the initial tumor bed? Is there a time interval or any other factors that would affect your management?

2 Answers

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Radiation Oncology · Memorial Sloan Kettering Cancer Center

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I'm aware of no great data in keratinocyte carcinoma that is available to help answer this question. A prospective study of patients with cutaneous squamous cell carcinoma found that among patients with high-risk primary tumors, recurrence at the site of margin-negative excision occurred in 25% within 6 years of surgery. About half of the local recurrence events happened within 12-24 months, however, some occurred as late as 5 years after surgery (Brantsch et al., PMID 18617440). Recently published guidelines suggest including the primary site if it was resected within the past 12-24 months, which is reasonable based on the kinetics of recurrence (Porceddu et al., PMID 32289475).

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Radiation Oncology · Henry Ford Health System

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I agree with Dr. @Dr. First Last's response. I usually tend to include the original site of the primary if the time interval between resection of the primary and RT for nodal recurrence is less than 2 years. Also, I am careful about how extensive my RT field will end up being if I go after the primary site. Occasionally, the primary site may be higher up in the scalp region and the nodal recurrence could be in the intraparotid or neck nodes. In that case, it is very difficult to include the primary site without causing significant toxicity in these patients who are usually elderly and tend to have other co-morbidities. Many are also immonusuppressed. In those situations, if there is no evidence of recurrence in the primary site, I treat only the neck nodes even if the disease free interval is less than 12-24 months.

A practical tip for treating the primary site - I obtain dose measurements using OSLs in case I am using an IMRT plan. Even with the use of a bolus, the skin surface may sometimes receive less than the planned dose. In those cases, I supplement the deficit with 1-2 fractions of electron RT towards the end of treatment.