4.1. Patients and Specimens Collection

All patients were recruited and treated at the National University Cancer Institute (NCIS), Singapore, between December 2014 and May 2016. WES and data analytics were performed at the National University of Singapore (NUS), Singapore. All procedures were conducted in accordance with the approved protocols and written informed consent was provided by the patients (File S1). Eligible patients were at least 21 years of age, had a histological or cytological diagnosis of advanced or metastatic solid malignancy and had recurrent disease for which tissue biopsy was indicated as part of routine clinical practice. This study was approved by the National Health Group Domain Specific Review Board IRB number 2014/00665

Each patient had 5 tumor biopsy samples obtained from one metastatic lesion using a single-pass radiologically-guided percutaneous biopsy technique. This technique involves the insertion of a coaxial needle together with its trocar into a lesion. The trocar is subsequently removed to allow for the introduction of a biopsy device that is composed of a needle with a 1.5 cm throw to facilitate multiple passes along acute angles from a single lesion via a single percutaneous access. Each biopsy sample was obtained at least 2 mm apart. One biopsy core was sent to the histopathology lab as part of routine clinical management while the remaining four tumor biopsy samples were analyzed using WES. Four patients had biopsies obtained from the lung (P3, P4, P5 and P6), four had peritoneal nodes biopsied (P1, P7, P8 and P9), three patients underwent a liver biopsy (P10, P11 and P12) and one patient each had a bone (P13) and supraclavicular lymph node (P2) biopsied. Germline samples were collected from each patient in the form of a buccal swab. If the germline sample failed quantitative QC, whole blood would be used as replacement. Samples with DNA concentration <4 ng/μL would be deemed to have failed QC. Radiological images were obtained as part of clinical care.