New findings suggest that biological agents are an effective and safe first-line treatment option for elderly patients with metastatic colorectal cancer, according to data presented at the ASCO 2020 Annual Meeting (Abstract 4017). Additionally, the study demonstrated that efficacy in progression-free survival (PFS) and overall response rate (ORR) was comparable to that of younger patients.
Colorectal cancer is a leading cause of morbidity and mortality, especially among older adults. According to the NCI, over 50 percent of new colorectal cancer diagnoses are in individuals 65 years or older. With a higher rate of comorbidities and organ function impairment, these patients are at an increased for treatment-related toxicities.
"Biological agents in combination with chemotherapy are recommended as first-line treatment of metastatic colorectal cancer; however, evidence guiding appropriate management in elderly patients with metastatic colorectal cancer is lacking," noted study author Pilar Garcia-Alfonso, MD, from the Hospital General Universitario Gregorio Maranon in Madrid, Spain.
Treatment guidelines are often based on randomized clinical trials instead of real-world data, according to the study authors. And so, due to inclusion and exclusion criteria, older patients are often underrepresented in these trials.
To better understand the impact of biological agents on older adults, Garcia-Alfonso and colleagues conducted a retrospective analysis comparing efficacy and safety outcomes in older versus younger patients with metastatic colorectal cancer who received first-line biological treatment.
Methods & Findings
Researchers utilized pooled data from five Spanish TTD Collaborative Group studies of adults with advanced colorectal cancer who received first-line treatment with chemotherapy plus bevacizumab, cetuximab, or panitumumab, stratified by age (>=65 vs. < 65 years). The primary endpoints of this analysis included PFS, overall survival (OS), ORR, and safety.
To compare the baseline clinical characteristics and the percentage of patients responding to treatment in the two age groups, as well as safety, researchers used a Chi-square test. The Kaplan-Meier method was employed to determine PFS and OS. For the comparison of the curves, the log-rank test and Cox regression model were used.
A total of 999 patients from five studies were included in the analysis. Forty-eight percent (N=480) were aged >=65 years and 52 percent (N=519) were aged < 65 years, according to the study authors. Among all patients, 733 (73.37%) were treated with bevacizumab, 189 (18.92%) received cetuximab, and 77 (7.71%) were administered panitumumab.
According to Garcia-Alfonso, the baseline characteristics indicate that patients 65 years and older were similar to their younger counterparts when it came to the number of pulmonary metastases, KRAS-mutated tumors, and surgery for primary tumors.
"The median PFS did not significantly differ between patients over or equal to 65 versus [those] under 65 years-9.9 months versus 9.4 months with a HR of 1.01," reported Garcia-Alfonso. "The median overall survival was significantly shorter in older patients versus younger patients (21.3 months vs. 25 months, HR 1.21; 95% CI 1.04-1.41; P=0.0132)."
Different factors may contribute to a shorter overall survival in the elderly population, such as ECOG performance status, a lower percentage of patients receiving an active treatment of the first-line therapy, and a shorter life expectancy among elderly patients, mainly those 75 years or older, Garcia-Alfonso noted.
Additionally, there was no significant difference between older versus younger patients in ORR (59% vs. 62%), according to Garcia-Alfonso. When it comes to safety, older patients experience more treatment-related grade >=3 adverse events, including diarrhea, fatigue, nausea, vomiting, decreased appetite, and hypertension.
"In conclusion, biological agents plus chemotherapy are an effective first-line option for elderly patients with metastatic colorectal cancer, with comparable efficacy to that observed in younger patients and a manageable safety profile," said Garcia-Alfonso.
Catlin Nalley is a contributing writer.
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