Adjuvant radiation reduces recurrence of localized cutaneous squamous cell carcinoma

Key takeaways:

• Adjuvant radiation decreased local and locoregional recurrence and nodal metastasis in the overall cohort, researchers found.
• Adjuvant radiation had no impact on disease-specific death.

ORLANDO — Patients with localized high-risk cutaneous squamous cell carcinoma who received adjuvant radiation after clear margin surgery experienced decreased risk for local recurrence and nodal metastasis, according to study results.

“Currently, our field lacks consensus on the use of adjuvant radiation after clear margin surgery, in part because we have limited data on its efficacy,” Nina A. Ran, MD, MS, micrographic surgery and dermatologic oncology fellow at Brigham and Women’s Hospital, said during a presentation at the American Society for Dermatologic Surgery Annual Meeting.

To evaluate the effect of adjuvant radiation, Ran and colleagues conducted a multicenter cohort study of patients with cutaneous squamous cell carcinoma treated for 1,267 localized high-risk tumors at 10 U.S. sites. All patients underwent Mohs surgery or wide local excision with confirmed clear margins.

The researchers also identified a higher-risk subgroup of 246 cutaneous squamous cell carcinomas that included patients who experienced bone invasion, lymphovascular invasion or met three of the four Brigham and Women’s Hospital staging system risk factors.

Study outcomes included 5-year risk for local recurrence, nodal metastasis, locoregional reoccurrence and disease-specific death.

Overall, 155 (12.2%) tumors received adjuvant radiation, including 74 (30%) from the higher-risk subgroup.

For the overall cohort and the higher-risk subgroup, patients who received adjuvant radiation had more risk factors than those who did not, including that they were younger, more immunosuppressed, had greater head/neck involvement or bone invasion, had poorer differentiation and had more perineural and lymphovascular invasion. Thus, the researchers used propensity score analysis to balance risk factors between the two treatment groups.

Ran and colleagues found that, compared with the control group, adjuvant radiation decreased the likelihood of local recurrence in the overall cohort by 53% at 5 years (cumulative incidence, 11.9% vs. 5.9%; sub-HR = 0.47; P = .04).

However, adjuvant radiation did not have an impact on local recurrence in the higher-risk subgroup (16.9% vs. 12.1%; sub-HR = 0.79), which could be because the study was underpowered for this analysis, according to Ran.

Adjuvant radiation also decreased nodal metastasis risk in the overall cohort (cumulative incidence, 9.5% vs. 4.6%; sub-HR = 0.46; P = .04) and in the higher-risk subgroup (21.1% vs. 9.6%; sub-HR = 0.42; P = .04).

Further, Ran and colleagues found that adjuvant radiation decreased locoregional recurrence in the overall cohort (cumulative incidence, 17.8% vs. 9%; sub-HR = 0.47; P = .01) and the higher-risk subgroup (cumulative incidence, 36.6% vs. 20%; sub-HR = 0.48; P = .02).

Adjuvant radiation had no impact on disease-specific death in either cohort, researchers found.

“It’s important to note that many patients are older and may have more challenges getting to and receiving radiation. Thus, it’s important to consider the patient’s functional status and the tumor’s baseline risk when discussing adjuvant radiation therapy,” Ran said.