PURPOSE: Bronchogenic carcinoma, low stage, presents as an intraparenchymal tumor (T1) that may involve bronchial/hilar lymph nodes (N1). This study investigates whether a risk ratio, T1N1/T1N0, derivable from the SEER data set, correlates with tumor features and host factors, predicts overall survival, and may be an indicator of tumor biologic potential.
METHODS: The SEER (1973-2002) Registry was investigted analyzing the incidence of AJCC T1 lung cancer cases according to nodal status, N0 and N1, and a risk ratio of incident cases per hundred thousand persons, T1N1/T1N0, was calculated. Plots of risk ratio versus host factors, tumor features, and overall survival were generated. Lung cancers that were equal to or greater than T2, N2, and M1 were excluded.
RESULTS: The overall ratio, T1N1/T1N0, for all non-small cell carcinomas is 0.13, less than for small cell undifferentiated carcinoma. The ratio increases with size, and is, respectively, 0.10 and 0.17 for tumors less than 2 cm. and those between 2 and 3 cm. Similarly, increasing histologic grade of adenocarcinoma from well differentiated to moderately differentiated to poorly differentiated increases the risk ratio from 0.07 to 0.15 to 0.20, respectively. As expected, the risk ratio for adenocarcinoma markedly exceeds that for bronchioloalveolar carcinoma. Interestingly, the risk ratio for African American (Blacks) is higher than that for Whites. The overall five-year survival for designated tumor cohorts varies directly with the risk ratio.
CONCLUSION: The risk ratio, T1N1/T1N0, reflects a tumor’s biologic potential and represents a surrogate indicator of relative cancer aggressiveness. Risk ratio increase with tumor size and grade and host factors, such as gender and race, and correlates with overall five-year survival.
CLINICAL IMPLICATIONS: The risk ratio, T1N1/T1N0, indicates the predilection for a localized T1 tumor to metastasize. Patient stratification may be performed using the risk ratio even in the absence of supporting imaging data for dissemination.
DISCLOSURE: Arnold Schwartz, None.