metastatic tumor vs malignance

metastatic tumor and malignance both are nouns.

Word	Noun	Adjective	Verb	Adverb
metastatic tumor	Yes	No	No	No
malignance	Yes	No	No	No

As nouns, malignance is a hypernym of metastatic tumor; that is, malignance is a word with a broader meaning than metastatic tumor:

metastatic tumor: a tumor that is malignant and tends to spread to other parts of the body
malignance: (medicine) a malignant state; progressive and resistant to treatment and tending to cause death

Other hypernyms of metastatic tumor include neoplasm, tumor, tumour, malignancy.

metastatic tumor (noun)	malignance (noun)
a tumor that is malignant and tends to spread to other parts of the body	quality of being disposed to evil; intense ill will
	(medicine) a malignant state; progressive and resistant to treatment and tending to cause death