NEW YORK (Reuters Health) – Recurrence after limited lung resection for small early-stage adenocarcinoma is three times more likely when the micropapillary component of the tumor is 5% or greater compared to less than 5%, according to a retrospective analysis.
“Our study has practical implications for the management of patients diagnosed with small early-stage lung ADC (adenocarcinoma) who are undergoing surgical resection,” the researchers point out. That is, for tumors with a micropapillary component of 5% or more, limited resection “may not be the ideal surgical resection.”
Dr. Prasad S. Adusumilli, at Memorial Sloan-Kettering Cancer Center in New York, and colleagues note that there have been no evidence-based criteria for choosing limited resection or lobectomy for the treatment of peripheral, early-stage lung adenocarcinoma. They therefore investigated the utility of recently proposed histologic classifications in this patient population.
For their study they identified 734 patients with stage I adenocarcinoma no larger than 2 cm: 258 underwent wedge resection or segmentectomy, and 476 underwent lobectomy. Median follow-up was 37 months in the limited-resection group and 32 months in the lobectomy group.
Regression tree analysis of data from a training subset of the patients identified tumors with a micropapillary (MIP) component of 5% or more as high risk for recurrence, the team reports in the Journal of the National Cancer Institute online August 7.
In the limited-resection group of patients, the 5-year cumulative incidence of recurrence (CIR) was significantly higher for those with high-risk tumors (34.2%) than those with low-risk tumors (12.4%; p<0.001).
“After adjustment for both vascular and lymphatic invasion, which were associated with recurrence in univariable analysis, the presence of an MIP component of 5% or greater remained independently associated with CIR (hazard ratio = 3.11; p=0.003),” according to the report. These results were replicated in a validation subset of the patients.
On the other hand, micropapillary status was not significantly associated with recurrence in patients who underwent lobectomy. The 5-year CIR was 19.1% when tumors had an MIP component of 5% or greater compared to 12.9% with tumors with a lower MIP component (p=0.13). The lack of association was also confirmed in a validation set.
“Our findings may carry increasing importance as the number of cases of early-stage lung ADC is expected to increase during the next decade as a result of the National Lung Screening Trial,” Dr. Adusumilli and colleagues comment.
However, they point out that intraoperative reporting of micropapillary morphologic patterns is not standard-of-care at present. “Hopefully, our findings will encourage further investigations to determine whether pathologists can recognize and report this feature on frozen sections of lung ADC,” they write.
Meanwhile, they conclude, “Given our findings, patients treated with (limited resection) whose tumors are determined to have MIP morphologic pattern by use of permanent sections may require completion segmentectomy or (lobectomy).”
SOURCE: Impact of Micropapillary Histologic Subtype in Selecting Limited Resection vs Lobectomy for Lung Adenocarcinoma of 2cm or Smaller
J Natl Cancer Inst 2013.
