People with the squamous cell carcinoma subtype of non-small cell lung cancer have significantly worse outcomes if these tumors are surrounded by fibrous stroma as opposed to thin stroma, say researchers in Japan.

As the investigators explain in the Journal of Thoracic Oncology (2011;6[9]:1460-1467), cancer tissue is composed of various stromal cells forming cancer-specific microenvironments. The researchers categorized a series of 220 pathological stage I lung squamous cell carcinomas into two histologic types: fibrous (n=85) and thin (n=135). Fibrous stroma was wider than some cancer nests and intermingled with plump fibroblast and/or collagen fibers. Thin stroma was narrower than the cancer nest and composed of thin collagen-fiber lamellae or infiltrative lymphocytes.

Patients with fibrous stroma-type tumors fared significantly worse than those with thin stroma-type tumors in terms of both recurrence-free survival and overall survival:

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  • The 5-year recurrence-free survival rate was 70% for patients with thin stroma and 50% for patients with fibrous stroma tumors.
  • The 5-year overall survival rate was 72.3% for patients with thin stroma and 55.5% for patients with fibrous stroma tumors.

Squamous cell carcinomas with fibrous stroma displayed higher invasive phenotype and were associated with significantly poor prognosis. The fibrous stroma-type tumors showed increased expression of proteins that have been found to increase cell motility and invasiveness.

These findings indicate that the microenvironment created by both the squamous cell carcinoma cells and the peritumoral fibroblasts contained in the stroma may make the cancer more aggressive.