'protumoral' originates from the Latin prefix 'pro-' meaning 'for' and the Late Latin/Latin root 'tumor' meaning 'a swelling', combined with the English adjectival suffix '-al' to form an adjective.

'tumor' comes from Latin 'tumor' meaning 'a swelling'; in modern medical English 'tumor' gave rise to the adjective 'tumoral', and in recent medical usage the prefix 'pro-' was attached to produce 'protumoral' (20th–21st century formation) to describe factors that support tumors.

Initially the elements referred literally to 'for a swelling' (pro- + tumor), but in modern medical usage the combined form came to mean specifically 'promoting tumor growth' or 'supportive of tumors'.