Adjuvant Radiation Effective For Cutaneous Squamous Cell Carcinoma With Perineural Invasion

Author: By Lynda Williams, Senior medwireNews Reporter 

medwireNews: US researchers recommend the use of adjuvant radiotherapy for patients undergoing surgery for cutaneous squamous cell carcinoma (cSCC) who have large-calibre perineural invasion or small-calibre perineural invasion with additional high-risk features. 

“Currently, adjuvant radiotherapy is recommended for cSCC with substantial perineural invasion”, explain John Carucci, from New York University School of Medicine, and co-authors in a letter to JAMA Dermatology. 

Between 2005 and 2015, 31 patients with cSCC at New York University who achieved a negative surgical margin were recommended for adjuvant radiation on the basis of a large-calibre invasion (≥ 0.1 mm diameter) or small-calibre invasion (< 0.1 mm) alongside tumour size above 2 cm, poor differentiation, invasion beyond subcutaneous fat, immunosuppression, or a head and neck location. 

Almost half (48.4%) of these patients completed adjuvant therapy consisting of 1500–6000 cGy over 10–30 sessions, the researchers say. 

Patients refused radiotherapy because of time constraints and concerns of adverse advents, and these individuals were more likely to be aged 70 years or older than those who received assigned radiotherapy (66.7 vs 33.3%). 

Treatment was well tolerated, with mild dermatitis affecting six patients who underwent adjuvant therapy. 

None of the patients experienced local recurrence over 5 years of follow-up, but five patients developed nodal metastases, none of whom had received adjuvant radiotherapy. 

Four of these five patients had large-diameter perineural invasion and all had at least one additional high-risk feature. For example, the patient with a small-diameter perineural invasion had a tumour size above 2 cm, invasion beyond subcutaneous fat, and location on the temple. 

In addition, four patients had a T2b tumour on the Brigham & Women’s Hospital staging system and one patient a T3 tumour. 

The estimated 5-year disease-free survival was 100% for patients given adjuvant radiotherapy and 68.8% for those who were not, a significant difference. 

While acknowledging the need for prospective multicentre trials, the team concludes: “Our data support the use of adjuvant radiotherapy for cSCC with perineural invasion and highlight the need to stratify patients at highest risk in an effort to identify those who might benefit from adjuvant radiotherapy to mitigate the risk of metastasis.” 

Reference  

Stevenson ML, Criscito MC, Wilken R, et al. Use of adjuvant radiotherapy in the treatment of high-risk cutaneous squamous cell carcinoma with perineural invasion. JAMA Dermatol; Advance online publication 1 July 2020. doi:10.1001/jamadermatol.2020.1984