metastatic tumor

NOUN
16 LETTERS · STARTS WITH M

metastatic tumor is a valid 16-letter word worth 21 points in Scrabble and 25 points in Words with Friends.

SCRABBLE WORDS WITH FRIENDS
M3E1T1A1S1T1A1T1I1C3T1U1M3O1R1
3 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 3 + 0 + 1 + 1 + 3 + 1 + 1 =21 PTS
DOUBLE WORD → 42TRIPLE WORD → 63
MEANING

What does metastatic tumor mean?