In response to chemoradiation, patients with stage I or II small cell lung cancer (SCLC) have a significantly longer overall survival than do those with stage III disease, according to a post hoc analysis of a randomized trial of chemoradiation in patients with early stages of SCLC.
The fact that overall survival is better in stage I and II than in stage III SCLC isn’t surprising. But the data confirm that stage I and II SCLC responds differently to chemoradiation than does stage III, providing a benchmark for safety and efficacy, according to the study authors.
The phase 3 CONVERT trial, from which the data were drawn, randomized patients with limited-stage SCLC to twice-daily (45 Gy in 30 fractions) or once-daily (66 Gy in 33 fractions) radiation after initiating cisplatin-etoposide chemotherapy (Lancet Oncol. 2017 Aug;18[8]:1116-25). Additional prophylactic cranial irradiation was permitted for those with an indication.
Contrary to the researcher’s hypothesis, once-daily radiation was not more effective for the primary outcome of overall survival in CONVERT, which limited enrollment to patients with local disease but did not stratify outcomes by SCLC stage. The purpose of the new post hoc analysis was to compare outcomes in those early-disease SCLC patients stratified by stage, which the authors noted is now recommended by several guidelines.
Because there were only four patients in CONVERT with stage I SCLC, those with either stage I or II SCLC, totaling 86 patients, were combined and then compared with the 423 with stage III SCLC.
At baseline, there were no significant differences between stage I/II and III groups for median age, smoking history, ECOG performance status, or dyspnea score at baseline. Similar proportions of patients completed the planned therapy.
However, the median survival was twice as long in the stage I/II group, compared with those with stage III SCLC (50 vs. 25 months), producing a hazard ratio for this outcome of 0.60 (P = .001). At 5 years, 49% of the stage I/II patients were alive, compared with 28% of the stage III patients (P = .001).
Other outcomes, such as progression-free survival at 5 years (47% vs. 26%; P = .003) also favored those with earlier-stage disease.
The incidence of adverse events associated with chemoradiation was not significantly different for the two groups, with the exception of acute esophagitis, which was less frequent in patients with earlier stage disease.
“The low incidence of severe toxic effects is a valid rationale to consider future radiotherapy dose intensification trials to improve outcomes” in patients with stage I/II disease, according to study author Ahmed Salem, MB, ChB, of the University of Manchester, England, and his coinvestigators.
The data from the post hoc analysis support guideline recommendations to stage even early and local SCLC when evaluating response to therapy in clinical trials, noted Howard (Jack) West, MD, of Swedish Cancer Institute, Seattle, in an accompanying editorial (JAMA Oncol. 2018 Dec 6. doi: 10.1001/jamaoncol.2018.5187). Dr. West suggested that such staging information might be useful when counseling patients about treatment options.
“These results imply that we may do our patients a disservice by dispensing with clinically relevant staging information that can lead to a more refined assessment of prognosis and optimal treatment,” Dr. West wrote.
SOURCE: Salem A et al. JAMA Oncol. 2018 Dec 6:e185335. doi: 10.1001/jamaoncol.2018.5335.
