1. (a tumor that is malignant and tends to spread to other parts of the body)
malignant tumor, malignant neoplasm, metastatic tumor
synonim: nowotwór złośliwy

2. (any malignant growth or tumor caused by abnormal and uncontrolled cell division
it may spread to other parts of the body through the lymphatic system or the blood stream)
cancer, malignant neoplastic disease: : synonim: nowotwór złośliwy

malignant tumour