There are 11 words that start with 'tumo'.
| tumor | tumors |
| tumour | tumoral |
| tumours | tumorous |
| tumorlike | tumorigenic |
| tumorigeneses | tumorigenesis |
| tumorigenicity | |
Note: These 11 words that start with 'tumo' are found from the USA & Canada version of the tournament Scrabble word list.