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Better outcomes anticipated when SCC invade smaller nerves

Squamous cell carcinoma tumors invading small-caliber nerves might have a better prognosis, according to study results.

Researchers in Boston studied 114 cases of primary squamous cell carcinoma (SCC) with perineural invasion (PNI) in 96 adults diagnosed from 1998 to 2008 (mean age at diagnosis, 71 years; 71% men). Hazard ratios for local recurrence, nodal metastasis, death from disease and overall death, adjusted for known prognostic factors, were used as main outcome measures.

Forty-six cases of the SCC were large-caliber nerve invasion and 68 cases were small-caliber nerve invasion. All but two cases involved unnamed nerves. In cases with no risk factors other than nerve invasion, only a single local recurrence occurred.

Statistically, tumors with large-caliber (≥0.1 mm) nerve invasion were more likely than small-caliber nerve invasions to have other risk factors, including tumor diameter greater than 2 cm (37% vs. 7%; P<.001), invasion beyond subcutaneous fat (41% vs. 10%; P<.001), vascular invasion (17% vs. 3%; P=.01), multiple nerve involvement (P<.001) and infiltrative growth (P=.01).

Large nerve invasion was related to increased risk for nodal metastasis (HR=5.6; 95% CI, 1.1-27.9) and death from disease (HR=4.5; 95% CI, 1.2-17.0) under univariate analysis.

Using multivariate analysis, local recurrence was predicted by tumor diameter of 2 cm or greater (HR=4.8; 95% CI, 1.8-12.7; and nodal metastasis was predicted by more than one risk factor (2 factors: HR=4.1; 95% CI, 1.0-16.6). Also hazard ratio for death from SCC when lymphatic invasion occurred was 15.3 (95% CI, 3.7-62.8), all-cause death risk was 1.1 (95% CI, 1.0-1.1) and invasion beyond subcutaneous fat predicted overall death with an HR of 2.1 (95% CI, 1.0-4.3.)

“SCC invading unnamed nerves of caliber smaller than 0.1 mm without other risk factors may have a good prognosis,” the researchers concluded. “However, perineurally invasive SCCs with other risk factors have a high risk of poor outcomes and may be considered for adjuvant therapy. Larger studies are needed to estimate the specific prognostic impact of large-caliber nerve invasion on SCC outcomes.”