Patients with cutaneous squamous cell carcinoma (CSCC) who have satellitosis or in-transit metastasis (S-ITM) had higher rates of recurrence and worse survival than those with T3 and T4 disease, according to research findings published in JAMA Dermatology. The survival was similar compared with node-positive disease.

S-ITM is a rare but clinically significant risk factor for recurrence among patients with cutaneous malignant neoplasms. Although established as a prognostic factor in melanoma and Merkel cell carcinoma, S-ITM is not incorporated into the CSCC staging systems.

Researchers conducted a multi-institutional retrospective study to investigate the prognostic significance of S-ITM for patients with CSCC. A total of 518 patients with CSCC who had undergone curative intent therapy between 2010 and 2020 were identified.


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Of the 518 patients, S-ITM was present in 72 (13.9%). The median age of the patients was 73.9 years, 82% were men, 96% were White non-Hispanic, and 35% were immunosuppressed. 

Researchers compared CSCC tumor recurrence and disease-specific survival (DSS) in patients with S-ITM and those with T3N0 (341 patients), T4N0 (36 patients), N1-N3 (70 patients), and M1 disease (19 patients).

For the overall study population, the median follow-up was 35.9 months (range, 0.1 to 196.0). The 2-year cumulative recurrence rate was 30.1%. The 5-year DSS was 64.0%.

When analyzed by disease group, the cumulative incidence of CSCC recurrence rates were lower in patients with T3N0 (hazard ratio [HR], 0.21; 95% CI, 0.14-0.30; P <.001) and T4N0 (HR, 0.36; 95% CI, 0.19-0.68; P =.001) disease compared with the S-ITM cohort. No significant difference in the recurrence rate was observed between patients with node-positive disease and those with S-ITM (HR, 0.74; 95% CI, 0.48-1.14; P =.16).

The 5-year DSS rates were 76% for patients with T3N0, 64% for patients with T4N0, 41% for patients with S-ITM, and 39% for patients with N1-N3. The 5-year DSS for patients with M1 disease could not be estimated.

Compared with the S-ITM cohort, the rate of DSS was similar among patients who were node-positive (HR, 0.77; 95% CI, 0.84-3.93; P =.30) and those with metastatic lesions (HR, 1.81; 95% CI, 0.84-3.93; P =.13).

The risk of disease-specific death was significantly lower in the T3N0 (HR, 0.23; 95% CI, 0.15-0.35; P <.001) and T4N0 (HR, 0.37; 95% CI, 0.19-0.76; P =.01) cohorts compared with the S-ITM cohort.

These results suggest that S-ITM is a risk factor for disease recurrence and skin cancer-related death associated with CSCC, according to the researchers. These findings were consistent with those reported for Merkel cell carcinoma and melanoma.

“Given that S-ITM may be a powerful prognostic factor, it should be incorporated into clinical staging systems,” the researchers wrote. They added that S-ITM has the potential to inform clinical decision-making for adjuvant therapy in a population that is still curable but at relatively high risk for recurrence and death from skin cancer.

Disclosures: Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures.

Reference

Smile TD, Ruiz ES, Kus KJ, et al.  Implications of satellitosis or in-transit metastasis in cutaneous squamous cell carcinoma: a prognostic omission in cancer staging systems. JAMA Dermatol. Published online February 23, 2022.  doi:10.1001/jamadermatol.2022.0001