Using the National Cancer Institute’s Common Terminology Criteria for Adverse Events (CTCAE), researchers from Columbia University, New York, and Fred Hutchinson Cancer Research Center, Seattle, identified six severe adverse event clusters in patients with advanced prostate cancer. The clusters “expand our understanding of the association among adverse events and may indicate that adverse events within each cluster should be treated and managed together,” the investigators reported in the Journal of Oncology Practice.
CTCAE data from a randomized clinical trial conducted by the Southwestern Oncology Group (SWOG-S9916) were used to identify severe adverse event clusters. That trial compared docetaxel plus estramustine (Emcyt) vs mitoxantrone plus prednisone in patients with advanced prostate cancer and “showed a beneficial effect on survival of docetaxel plus estramustine, making it the new standard of care for pathologically confirmed adenocarcinoma of the prostate and progressive metastatic disease of stage D1 or D2 disease,” the authors noted. “Although the original trial was conducted more than a decade ago, docetaxel treatment remains a standard of care for patients with advanced prostate cancer today. Thus, the adverse event data remain relevant.”
The new analysis included 323 patients who experienced at least one grade 3 or higher adverse event. The median age of the study cohort was 73 years; 83% were white, and 15% were African American. “The median prostate-specific antigen level at random assignment was 99.2 ng/mL,” the researchers reported.
Adverse Event Types Captured
A total of 109 distinct adverse event types with at least one grade 3 or higher event were captured using the CTCAE. These events were grouped into 92 categories, and 23 of them had more than 10 events and so were included in the cluster analysis. “Spearman rank correlations (r) among those severe adverse events within a cluster were also calculated and were expressed as an absolute value between 0 and 1, with 0 representing no correlation and 1 representing perfect correlation,” the authors explained.
Four clusters were considered to have moderate associations. These clusters were nausea, vomiting, and anorexia (n = 35, r = 0.45); anemia and transfusion (n = 20, r = 0.38); joint/bone (myalgia, arthralgia, and arthritis) and muscle weakness (n = 26, r = 0.29); and neutrophils/granulocytes, febrile neutropenia, and leukocytes/lymphopenia (n = 114, r = 0.29). “Two clusters had weak associations,” the investigators added: “fatigue/ malaise/lethargy and dehydration (n = 66, r = 0.12); and constipation, infection without neutropenia, and abdominal pain/cramping
(n = 35, r = 0.13).”
Commenting on the real-life implications of the study, the authors wrote: “Capturing adverse events using the CTCAE, which is standard practice in all clinical trials, can be used to understand the relationships among adverse events and to identify adverse events clusters when patient-reported outcomes are unavailable.”