PURPOSE - This study seeks to clarify the modern prognostic significance of visceral pleura invasion (VPI) in Stage IB (T2aN0M0) non-small cell lung cancer (NSCLC) within the context of the 7th edition TNM classification using the data set from a recent prospective multicenter trial.
PATIENTS AND METHODS - 1111 early-stage NSCLC patients participating in the ACOSOG Z0030 trial (1990-2004) underwent curative pulmonary resection. After excluding T2b tumours (>5 cm and ≤ 7 cm) and non-size-based T2 factors other than VPI, 289 patients were categorized as Stage IB NSCLC - T2aN0M0 - according to the AJCC 7th edition classification. The patients were divided into three groups according to size and VPI: tumours ≤ 3 cm with VPI (Group I, "VPI-alone", n=83), tumours>3 cm and ≤ 5 cm without VPI (Group II, "Size-alone", n=156), and tumours>3 cm and ≤ 5 cm with VPI (Group III, "VPI+Size", n=50). Multivariate Cox regression analysis was used to assess the association of VPI and size with survival, adjusting for age, gender, histology and type of resection.
RESULTS - VPI in Stage IB was identified in 133 patients (46.0%). Survival analysis in these patients identified an optimal cutpoint for survival based on size of 3.1cm. Group III (VPI+Size) had a 5-year survival rate of 55.0% significantly shorter when compared to Group I (VPI-alone=68.3%, p=0.009), and Group II (Size-alone=67.2%, p=0.021). No difference was found between Groups I and II. Multivariable analysis showed that VPI associated with size was an independent negative prognostic factor of long-term survival, along with older age and limited resection.
CONCLUSIONS - Stage IB patients with VPI and tumours>3 cm and ≤ 5 cm have significantly worse prognosis than those with 'T2a' tumours on the basis of VPI or tumour size alone. This finding would suggest upstaging these patients from the current IB status to Stage IIA.
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