Bronchogenic carcinoma may present as an intraparenchymal tumor (T1). Recurrence increases and overall survival decreases with the presence of bronchial/hilar lymph node metastases (N1). This study investigates epidemiologic data and tumor characteristics, derivable from the SEER data set, in order to identify factors that predict early aggressive behavior.
The SEER Registry was investigated analyzing the incidence of lung cancer cases from 1973 - 2001, which were AJCC T1 lung cancers. The incidences of these tumors were analyzed according to nodal status, N0 and N1, and a risk (odds) ratio of T1N1/T1N0 was generated as a surrogate indicator of relative cancer aggressiveness. Lung cancers that were equal to or greater than T2, N2, and M1 were excluded.
The overall risk odds ratio, T1N1/T1N0, for all non-small cell carcinomas is 0.13, significantly less than for small cell undifferentiated carcinoma. The ratio increases with size of the tumor; respectively 0.09 and 0.15 for tumors less than 2 cm., and those between 2 and 3 cm. Similarly, increasing the 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 odds risk ratio, T1N1/T1N0, represents a parameter indicating metastatic potential. Classical features of tumor size and grade are associated with increasing risk ratios. Epidemiologic data, such as racial/ethnic background and gender are also predictive of risk ratio differences.
The risk ratio, T1N1/T1N0, indicates the relative risk of a T1 tumor to metastasize to N1 nodes and represents a marker of relative tumor aggressiveness. Patient stratification may be performed using the risk ratio even in the absence of supporting imaging data for dissemination.
A.M. Schwartz, None.