Results of clinical trials evaluating chemotherapy regimens for advanced pancreatic and lung cancers “tended to correctly estimate survival for Medicare patients aged 65 to 74 years but to overestimate survival for older Medicare patients by 6 to 8 weeks,” Elizabeth B. Lamont, MD, MS, of Massachusetts General Hospital Cancer Center in Boston, and colleagues reported in the Journal of the National Cancer Institute. “These ‘real world’ results may help inform treatment discussions between older patients with these common advanced cancers and their oncologists,” the researchers wrote.
In the United States, “patients who enroll in chemotherapy trials seldom reflect the attributes of the general population with cancer, as they are often younger, more functional, and have less comorbidity,” the investigators observed. “We compared survival following three chemotherapy regimens according to the setting in which the care was delivered (ie, clinical trial vs usual care) to determine generalizability of clinical trial results to unselected elderly Medicare patients.”
Using Surveillance, Epidemiology, and End Results Program (SEER)–Medicare data, the researchers estimated survival for 14,097 patients age 65 years or older with advanced pancreatic or lung cancer who had received one of three guideline-recommended first-line chemotherapy regimens. Their survival was compared with that of 937 patients, without age restrictions, but with the same diagnosis and stage of disease, similarly treated in clinical trials. These patients treated with standard first-line chemotherapy regimens in the clinical trial setting were identified using data from the National Cancer Institute–sponsored cooperative clinical trial group Cancer and Leukemia Group B, now a part of the Alliance for Clinical Trials in Oncology.
The median age of the clinical trial patients was 9.5 years younger than the elderly Medicare patients. “For each tumor type, Medicare patients who were 75 years or older had median survivals that were 6 to 8 weeks shorter than those of trial patients,” the researchers reported.
Survival times for patients with advanced pancreatic cancer treated with single-agent gemcitabine were 4.3 months for the elderly Medicare patients vs 5.8 months (P = .03) for the clinical trial patients. Respective survival times were 7.3 vs 8.9 months (P = .91) for patients with stage IV non–small-cell lung cancer treated with carboplatin and paclitaxel and 8.2 vs 10.2 months (P ≤ .01) for patients with extensive-stage small cell lung cancer treated with cisplatin/etoposide. For younger Medicare patients, survival times were similar to those of clinical trial patients.
“In applying these findings to any age group, it is essential to recognize that there is heterogeneity in important attributes like functional status, comorbidity, and general health status. Experts in geriatric oncology therefore advocate for comprehensive geriatric assessments that take into account many of these factors and that can assist in selecting patients for treatment, including participation in clinical trials,” the authors noted. “Given the similarly in survival between Medicare patients aged 65 to 74 years and the trial patients we studied, physician selection for usual-care treatment appears to have been reasonable.” ■
Lamont EB, et al: J Natl Cancer Inst 107:336, 2014 (print January 2015).