Squamous cell carcinomas 2 mm or thicker were most likely to metastasize

Cutaneous squamous cell carcinomas >2 mm thick were associated with a significant risk for metastasis, according to the results of a recent trial. Tumors 6 mm or thicker were even more likely to metastasize, and also carried increased risk for local recurrence.

Researchers at Eberhard Karls Universität in Tübingen, Germany assessed potential risk factors for metastasis or local recurrence of squamous cell carcinomas in 615 patients. Primary endpoints were time to metastasis and time to local recurrence.

The study team found that tumors smaller than 2 mm did not metastasize. Twelve of 318 patients with tumors between 2.1 mm and 6.0 mm thick had metastasis, as did 14 of 90 patients with tumors thicker than 6.0 mm.

The key prognostic factors for metastasis were increased tumor thickness, immunosuppression, localization at the ear and increased horizontal size (see table).

Likewise, the risk of local recurrence depended on increased tumor thickness (RR=6.03; 95% CI, 2.71-13.43) and desmoplasia (RR=16.11; 95% CI, 6.57-39.49).

Key prognostic indicators for metastasis

Factor	Hazard Ratio
Increased tumor thickness	4.79
Immunosuppression	4.32
Localization at the ear	3.61
Increased horizontal size	2.22

Lancet Oncol. 2008;9:713-720.