NO DIFFERENCE WITH LUNG CANCER STAGING METHODS

For mediastinal nodal staging of potentially resectable non–small cell lung cancer, there were no survival differences at 5 years with endosonography or mediastinoscopy in a post hoc analysis of the ASTER trial.

The Assessment of Surgical Staging vs Endosonographic Ultrasound in Lung Cancer (ASTER) trial compared surgical staging using mediastinoscopy with staging that employed a combination of endobronchial and transesophageal ultrasound followed by mediastinoscopy if negative.

The results, published in JAMA in 2010, were clear: the endosonographic strategy was significantly more sensitive for diagnosing mediastinal nodal metastases than surgical staging (94% vs 79%).

The post hoc analysis, published online September 13 as a research letter in JAMA, found no difference in 5-year survival between the two staging strategies.

Jouke T. Annema, MD, PhD, of the Academic Medical Center, Amsterdam, the Netherlands, and colleagues obtained survival data through patient records, death registers, or contact with general practitioners for 121 of 123 patients who underwent endosonographic staging and 116 of 118 who underwent surgical staging.

The prevalence of mediastinal nodal metastases was 54% in the endosonography group and 44% in mediastinoscopy group.

The estimated median survival was 31 months with the endosonographic strategy and 33 months with the surgical strategy. Five-year survival was also similar in subgroups with N2/N3 or N0/N1 metastases.

Table.

5-Year Survival	Endosonography	Mediastinoscopy	Odds Ratio (95% CI)
Overall	35%	35%	0.97 (0.77 - 1.40)
N2/N3	17%	19%	0.87 (0.34 - 2.25)
N0/N1	54%	48%	1.27 (0.62 - 2.60)
CI, confidence interval.

Since the original results of the ASTER trial were published, guidelines on lung cancer management underwent "major revisions and now advocate endosonography instead of mediastinoscopy as the initial step for mediastinal nodal staging," the investigators note in their letter. "The endosonographic strategy is more accurate, less invasive, and reduces unnecessary thoracotomies."

It is important to note, they say, that ASTER was powered to detect a difference in diagnostic sensitivity, not survival, as reflected by the wide confidence intervals.

"If a survival difference between the strategies exists, it is likely to be small and a larger sample size may be needed to detect it. However, randomized trials to detect a survival difference based on staging strategy are not likely to be conducted as the endosonographic strategy is now advised in clinical guidelines," the investigators write.

These findings are "not surprising at all," Gerard A. Silvestri, MD, Division of Pulmonary and Critical Care Medicine, Medical University of South Carolina, Charleston, who was not involved in the study, told Medscape Medical News.

"First, the initial study was meant to assess the most effective way to stage patients. In the end, both groups were staged well by either method," he explained. And second, as the authors point out, "The trial was not powered (meaning not enough patients were included) to detect a survival difference were one present," Dr Silvestri noted.

The post hoc analysis had no specific funding. Dr Annema has received material and financial support for educational endobronchial and esophageal ultrasound courses from Hitachi, Pentax, COOK, and Symbionix through the Department of Respiratory Medicine at his institution. Dr Silvestri has disclosed no relevant financial relationships.