Sublobar Resection the 'New Standard of Care' in Small-Sized NSCLC?

VIENNA -- Sublobar resection was on par with lobectomy for non-small cell lung cancer (NSCLC) tumors with a diameter of 2 cm or less, according to results from the CALGB 140503 (Alliance) trial presented here.

For the trial's primary endpoint of disease-free survival (defined as NSCLC recurrence or death by any cause), sublobar resection was non-inferior to lobar resection (HR 1.01, 90% CI 0.83-1.24, P=0.0176 for non-inferiority), reported Nasser Altorki, MD, of Weill-Cornell Medicine-NewYork Presbyterian Hospital in New York City.

"The results of this trial and JCOG 0802 establishes sublobar resection as the new standard of care for this subset of patients," Altorki said in presenting the results at the World Conference on Lung Cancer (WCLC).

The study discussant at the session, Hisashi Saji, MD, PhD, of St. Marianna University School of Medicine in Kawasaki, Japan, who was the lead investigator for the JCOG 0802 trial, agreed that sub-lobar resection -- including wedge resection and segmentectomy -- must be considered as a standard of care for small-sized peripheral non-small cell lung cancer without lymph node metastasis.

Saji also suggested that sublobar resection "reserved the possibility of more extensive treatment for upcoming life-threatening disease" in these patients, which could include second primary cancers, respiratory disease, or cardiovascular disease.

Secondary Findings

At a median follow-up of 7 years, 5-year disease-free survival (DFS) among the 340 patients in the sublobar group was 63.6%, compared with 64.1% for the 357 patients in the lobar resection cohort.

Overall survival (OS) was comparable between the two groups as well, with 95 deaths in the sublobar arm and 103 in the lobar arm (HR 0.95, 90% CI 0.75-1.21, P=0.014 for noninferiority). Five-year OS was 80.3% and 78.9% in the sublobar and lobar arms, respectively.

A post-hoc exploratory analysis of DFS showed that sublobar resection was also non-inferior to lobar resection across the major demographic and features, including sex, age, tumor location, tumor size, histology, smoking status, and performance status.

Disease recurrence was observed in 29.8% of the patients in the lobar arm and 30.6% in the sublobar arm. There were no significant differences between the lobar and sublobar arms in terms of isolated local recurrence (8.1% and 9.9%, respectively), regional only (2.6% and 1.8%), local/regional (2.0% and 3.6%), local distant (4.3% and 4.8%), or any distant recurrence (16.9% and 15.3%).

As for pulmonary function, the magnitude of reduction in forced expiratory volume in the first second and in forced vital capacity favored the sublobar arm, but the difference "may not be clinically significant," Altorki said.

Study Rationale and Design

Altorki pointed out that lobar resection has been the surgical standard of care for clinical stage I, node negative (cT1N0) NSCLC since 1995, while sublobar resection was reserved for a subset of patients with marginal pulmonary reserve. However, "with better imaging modalities, better staging, small tumors, and definitely lung cancer screening, there has been resurging interest in sublobar resection," he said.

The JCOG 0802 trial reported that, in fit patients with cT1aNO NSCLC ≤2 cm, segmentectomy was not inferior to lobectomy in terms of the primary endpoint of overall survival.

The CALGB 140503 (Alliance) trial enrolled 1,080 patients with clinical stage Ia NSCLC between June 2007 and March 2017. Patients were eligible if they had pathologically confirmed NSCLC and node-negative disease at level 10 and up to two mediastinal stations prior to randomization.

Of the 1,080 patients enrolled, 697 patients were intraoperatively randomly assigned to either lobar or sublobar resection (either segmentectomy or wedge resection, according to surgeon choice). Altorki reported that 58% of the procedures in the sublobar arm were wedge resections.

Patients were a median age of 67.9 years, 90.0% were white, and 57.4% were female. Most (73.6%) had an ECOG performance status of 0, while 25.0% had a performance status of 1.

The trial was stratified by tumor size, smoking status, and histology.

Slightly more than half of patients (50.8%) had tumor size between 1.0 and 1.5 cm, 40.9% had tumors >1.5-2 cm, and 8.3% had tumors less than 1.0 cm.

About half of the participants were former smokers, 40.9% were current smokers, and 9.0% were never smokers; the majority (63.3%) had adenocarcinoma, while 14.1% had squamous carcinoma.

"The major clinical and demographic were well balanced between the two arms of the trial, especially the three stratification factors, and particularly tumor sizes," Altorki observed.

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