ERBB2 and gastroesophageal junction adenocarcinoma: This is currently being investigated in the ongoing Neoadjuvant Study Using Trastuzumab or Trastuzumab With Pertuzumab in Gastric or Gastroesophageal Junction Adenocarcinoma (EORTC INNOVATION) and FLOT vs FLOT/Herceptin/Pertuzumab for Perioperative Therapy of HER-2 Expressing Gastric or GEJ Cancer (AIO PETRARCA) perioperative studies.