In this study, we evaluated the clinical utility of detecting KRAS mutations in circulating cell‐free (ccf)DNA of metastatic colorectal cancer patients. We prospectively recruited 94 metastatic colorectal cancer patients. Circulating cell‐free DNA was extracted from plasma samples and analyzed for the presence of seven KRAS point mutations. Using the Invader Plus assay with peptide nucleic acid clamping method and digital PCR, KRAS mutations were detected in the ccfDNA in 35 of 39 patients previously determined to have primary tumors containing KRAS mutations using the Luminex method, and in 5 of 55 patients with tumors containing wild‐type KRAS. Curative resection was undertaken in 7 of 34 patients with primary and ccfDNA KRAS mutations, resulting in the disappearance of the mutation from the cell‐free DNA in five of seven patients. Three of these patients had tumor recurrence and KRAS mutations in their ccfDNA reappeared. Epidermal growth factor receptor blockade was administered to 24 of the KRAS tumor wild‐type patients. Of the 24 patients with wild‐type KRAS in their primary tumors, three patients had KRAS mutations in their ccfDNA and did not respond to treatment with epidermal growth factor receptor (EGFR) blockade. We also detected a new KRAS mutation in five patients during chemotherapy with EGFR blockade, before disease progression was detectable with imaging. The detection of KRAS mutations in ccfDNA is an attractive approach for predicting both treatment response and acquired resistance to EGFR blockade, and for detecting disease recurrence.

Background: Liquid biopsy is a collective term that refers to the analysis of tumor-derived biomarkers isolated from biological fluids of cancer patients. Recently, many authors reported the usefulness of liquid biopsy for the management of malignancy. Summary and Key Messages: The peripheral blood of cancer patients is a pool of cells and/or cell products derived from the primary or metastatic tumor, including circulating tumor cells (CTCs), circulating free (cf) DNA or RNA, and exosomes containing proteins, nucleic acids, and lipids. CTCs are tumor cells that can be isolated from peripheral blood. Free circulating DNA with a tumor-specific mutation is called circulating tumor DNA (ctDNA). Some patients who undergo curative surgery experience recurrent disease, which can be due to the presence of minimal residual disease (MRD). Thus, MRD indicates a high risk of relapse. Detection of ctDNA or CTC after surgery is a direct proof of MRD. Molecular volume (e.g., the number of CTCs and level of ctDNA) might reflect tumor burden, thus high molecular volume may indicate poor prognosis. The most notable application of liquid biopsy in cancer is to understand spatial and temporal heterogeneities. Heterogeneity is one of the causes of refractoriness and hampers prediction of chemotherapeutic effect. Emerging mutations that are not present in primary tumors but are found in their metastases can be detected in ctDNA. Some colorectal cancer patients with wild-type RAS do not respond to epidermal growth factor receptor blockade. In a subset of these patients, RAS mutation is detected in ctDNA, indicating heterogeneity.

We recruited 56 colorectal cancer patients and compared the mutational spectrum of tumor tissue DNA, circulating cell‐free DNA (ccfDNA) and circulating tumor cell (CTC) DNA (ctcDNA) to evaluate the potential of liquid biopsy to detect heterogeneity of cancer. Tumor tissue DNA, ccfDNA, and ctcDNA were extracted from each patient and analyzed using next‐generation sequencing (NGS) and digital PCR. To maximize yields of CTC, three antibodies were used in the capture process. From 34 untreated patients, 53 mutations were detected in tumor tissue DNA using NGS. Forty‐seven mutations were detected in ccfDNA, including 20 not detected in tissues. Sixteen mutations were detected in ctcDNA, including five not detected in tissues. In 12 patients (35.3%), mutations not found in tumor tissues were detected by liquid biopsy: nine (26.5%) in ccfDNA only and three (8.8%) in ctcDNA only. Combination analysis of the two liquid biopsy samples increased the sensitivity to detect heterogeneity. From 22 stage IV patients with RAS mutations in their primary tumors, RAS mutations were detected in 14 (63.6%) ccfDNA and in eight (36.4%) ctcDNA using digital PCR. Mutations not detected in primary tumors can be identified in ccfDNA and in ctcDNA, indicating the potential of liquid biopsy in complementing gene analysis. Combination analysis improves sensitivity. Sensitivity to detect cancer‐specific mutations is higher in ccfDNA compared with ctcDNA.

BACKGROUND: Survival prediction systems such as the Palliative Prognostic Index (PPI), which includes the Palliative Performance Scale (PPS), are used to estimate survival for terminally ill patients. Oncologists are, however, less familiar with the PPS in comparison with the Eastern Cooperative Oncology Group (ECOG) performance status (PS). This study was designed to validate a simple survival prediction system for oncologists, the Performance Status–Based Palliative Prognostic Index (PS‐PPI), which is a modified form of the PPI based on the ECOG PS.METHODS: This multicenter, prospective cohort study enrolled all consecutive patients who were referred to 58 palliative care services in Japan. The primary responsible physicians rated the variables required to calculate the PS‐PPI and the PPI. Patient survival in these risk groups was compared, and the sensitivity and specificity of the PS‐PPI and the PPI were evaluated. Patients were subclassified as patients receiving care from in‐hospital palliative care teams, palliative care units, or home‐based palliative care services. Subsets of patients receiving chemotherapy were also analyzed.RESULTS: This study included 2346 patients. Survival predictions based on the PPI and the PS‐PPI differed significantly among the 3 risk groups (P < .001). The PS‐PPI was more sensitive, whereas the PPI was more specific. All areas under the receiver operating characteristic curves of both indices were >0.78 for predicting survival at all times, from 3 weeks to 180 days.CONCLUSIONS: In predicting the prognosis of patients with advanced cancer, the PS‐PPI was as accurate as the PPI. The PS‐PPI was useful for short‐ and long‐term survival prediction and for the prediction of survival for patients undergoing chemotherapy. Cancer 2017;123:1442–1452. © 2016 American Cancer Society.