Rationale: Whether histologic subtype of non-small cell lung cancer (NSCLC) has an important effect on prognosis after surgery is unknown.
Objectives: We hypothesized that we could predict mortality more effectively by integrating precise tumor size and histology rather than relying on conventional staging.
Methods: We used the SEER (Surveillance, Epidemiology, and End Results) registry. Inclusion criteria were as follows: (1) primary squamous cell or adenocarcinoma; (2) potentially curative surgery, defined as a lobectomy or bilobectomy; (3) lymph node dissection performed; and (4) pathologic stage IA or IB.
Measurements and main results: From 1988 to 2000, 7,965 patients were included. For both all-cause and lung cancer-associated mortality, tumor size demonstrated the strongest association (log-rank P < 0.0001 for each). When tumors were small (</=2 cm), lung cancer-associated mortality was similar for adenocarcinoma when compared with squamous cell carcinoma. When tumors were 3 cm or larger in size, lung cancer-associated mortality was higher for adenocarcinoma. The increased risk of lung cancer-associated mortality with adenocarcinoma was more pronounced in those younger than 65 years. Survival prediction using precise size and histology had much better discriminatory power than conventional TNM (tumor-node-metastasis) staging (P = 0.005).
Conclusions: Staging that takes into account size, histology, late recurrence risk, and patient age is more accurate than the current TNM system and is clinically relevant because improved prediction can facilitate better decisions on the use of adjuvant chemotherapy.