BACKGROUND: There is no standardized assessment of symptomatic events in metastatic colorectal cancer (mCRC) despite disease symptoms that affect treatment decisions. Data from 3 first-line panitumumab in mCRC trials were retrospectively analyzed to assess whether early tumor shrinkage (ETS) and depth of response (DpR) were associated with time to occurrence of tumor-related symptoms.
PATIENTS AND METHODS: Patients with RAS wild-type mCRC from PRIME, PEAK, and Study 314 were included. ETS was defined as a reduction of ≥ 30% in the sum of the longest diameters of lesions at 8 weeks. DpR was calculated as maximum percentage change in tumor size from baseline to nadir. The proportion of patients who developed symptoms (including a composite symptomatic endpoint) during study treatment was calculated. This study was registered at ClinicalTrials.gov as PRIME (NCT00364013), PEAK (NCT00819780), and Study 314 (NCT00508404).
RESULTS: Overall, data of 659 patients were analyzed. Onset of symptoms was delayed in patients with ETS ≥ 30% versus ETS < 30% and in patients with greater DpR. In patients with symptoms at baseline who experienced ETS ≥ 30%, overall survival was similar to that seen for patients without symptoms at baseline.
CONCLUSION: Both ETS and DpR were associated with delayed onset of symptoms in RAS wild-type mCRC patients. Treatments with high cytoreductive potential may delay symptom development.