What is the role of adjuvant radiotherapy in the treatment of cutaneous squamous cell carcinoma with perineural invasion?
BACKGROUND
Perineural invasion (PNI) in cutaneous squamous cell carcinoma (SCC) is infrequent, occurring in 2.5% to 14% of patients, but it is important prognostically, because it carries an increased risk of recurrence and metastasis. Although both excision and Mohs micrographic surgery (MMS) are used to treat SCC with PNI, postoperative radiation therapy (XRT) often is recommended to minimize the risk of recurrence. To date, the effectiveness of adjuvant XRT in this setting has not been determined definitively.


METHODS
The authors evaluated the effectiveness of adjuvant XRT in treating SCC with PNI by performing a thorough literature review.


RESULTS
For SCC with PNI, the local control rate after MMS with or without XRT was from 92% to 100% compared with a control rate from 38% to 100% after standard excision with or without XRT. A better prognosis was associated with negative pretreatment magnetic resonance imaging or computed tomography findings than with positive radiographic evidence of PNI. Primary SCC with PNI was associated with better local control than recurrent SCC with PNI. When treatment outcomes were stratified by PNI type, SCC with microscopic PNI and SCC with extensive PNI had local control rates from 78% to 87% and from 50% to 55%, respectively. Adjuvant XRT was associated in selected patients with 100% local control.


CONCLUSIONS
Few studies addressed the effectiveness of adjuvant XRT in patients who have SCC with PNI. Although XRT has been established as an adjuvant treatment for selected patients, the extent of nerve involvement by tumor, particularly in the setting of other high-risk features, may be helpful in defining its role. In the future, a multicentered, prospective, randomized clinical trial will be needed to assess the true efficacy of adjuvant XRT in the treatment of patients with SCC and PNI.
Han
Anne
A
College of Physicians and Surgeons, Columbia University Medical Center, New York, New York 10032, USA. ah2203@columbia.edu
Ratner
Désireé
D
D002294:Carcinoma, Squamous Cell / Q000473:pathology / Q000532:radiotherapy* / Q000556:secondary; D006801:Humans; D009361:Neoplasm Invasiveness; D010525:Peripheral Nerves / Q000473:pathology; D010524:Peripheral Nervous System Neoplasms / Q000473:pathology / Q000532:radiotherapy*; D018714:Radiotherapy, Adjuvant; D012878:Skin Neoplasms / Q000473:pathology / Q000532:radiotherapy*