ERBB2 and gastrointestinal stromal tumor: High numbers of tumor-infiltrating NK cells have been correlated with good prognosis and lower relapse rates in patients affected by HER2-positive and triple negative breast cancer, gastrointestinal stromal tumor (GIST), neuroblastoma, head and neck cancer, lung, prostate cancer and melanoma [48,49,50,51,52,53,54].