LOS ANGELES – A novel genetic assay helps identify patients with early, aggressive lung cancer who might benefit from adjuvant therapy.
The assay, marketed as Pervino Lung RS by Life Technologies, is the only lung cancer signature to undergo blinded validation in two large cohorts from different countries, one in the United States and one in China (Lancet 2012;379:823-32).
Dr. Johannes Kratz
It assesses expression of 14 genes involved in lung cancer tumorigenesis, including ones on the EGFR and KRAS signaling pathways. The assay provides considerably more prognostic information than do conventional criteria proposed by the National Comprehensive Cancer Network (NCCN) as defining high-risk tumors warranting treatment, according to Dr. Johannes R. Kratz, who reported the data at the annual meeting of the Society of Thoracic Surgeons.
The assay results were used to stratify the 269 study patients who had undergone resection of T1a node-negative and nonmetastatic, nonsquamous, non–small cell lung cancer (NSCLC) into groups with distinctly different 5-year survival rates.
Compared with their counterparts in the low-risk group, those in the intermediate- and high-risk groups had a respective doubling and more than tripling of the risk of death, said Dr. Kratz, who was the study’s lead investigator.
As a result of recommendations for CT screening in patients at high risk for lung cancer, resections of small node-negative tumors that are in fact deadly are likely to increase, he observed. Nearly 30% of all patients with stage IA tumors – the lowest level in the current classification system – will nonetheless die in the subsequent 5 years.
"These tumors with highly aggressive tumor biology can now be identified reliably with a prognostic gene signature. The identification of these small but deadly tumors may allow for personalized patient prognosis and could allow us to maximize the benefit of the early detection of these small but deadly tumors via low-dose CT screening," he added.
The current postoperative standard of care for stage IA disease is simply observation, according to Dr. Kratz, a former surgical resident at the Massachusetts General Hospital in Boston, and now a postdoctoral fellow at the University of California, San Francisco.
However, "we should strongly consider changing the way we think about patients with high-risk T1a tumors," he recommended. To that end, a randomized controlled trial of assay-guided adjuvant chemotherapy for early lung cancer is underway in China among roughly 1,000 patients.
Dr. Kratz said that studies to date have not examined a potential prognostic role of the assay in EGFR (epidermal growth factor receptor) mutations. "We haven’t performed an additional mutation analysis on these patients’ EGFR. The original assay was designed to work on patients with resected paraffin-embedded specimens and not fresh-frozen tissue specimens. As a result, it is difficult for us to do extensive EGFR mutation analysis. But that’s definitely something to consider, and it would be nice to explore that association."
It remains to be seen whether the assay, in fact, predicts chemotherapy benefit, he acknowledged in a related press conference. But research has suggested that such prognostic signatures in lung cancer are also predictive (J. Clin. Oncol. 2010;28:4417-24). "That is what we hope to show in the China trial as well," he said.
In the reported study, patients with T1a tumors were drawn from the initial validation cohorts. Fully 40% were under age 60. "This is important, because ... we’d like to be more aggressive in younger patients, both because they can tolerate it and we are more likely to treat them more aggressively," he noted.
The patients’ actual 5-year mortality rate was 32% overall, showing that "these tumors are as deadly as advertised."
The main study results, reported at the meeting and also published (JAMA 2012;308:1629-31), showed that the 5-year actuarial overall survival was 83%, 69%, and 52% among patients in assay-defined low-, medium-, and high-risk groups, respectively (P less than .0001).
In multivariate analyses, relative to their counterparts in the low-risk group, patients in the intermediate-risk group had a 2.0-fold higher risk of death (P = .04) and patients in the high-risk group had a 3.3-fold higher risk (P = .00).
The assay also showed good risk discrimination in analyses restricted to the smallest of tumors, those measuring 1.5 cm or less (P = .001 for difference across groups) and even those measuring 1.0 cm or less (P = .008).
And when compared with tumor size alone, the combination of the assay and tumor size significantly improved on the identification of patients who died (c-statistic, 0.68 vs. 0.57; P less than .0001).