I have irregular sized bumps (5 or 6) on the back of my tongue, that are pinkish & 1 is as long as about an inch, 1 is very small. i also have a sore throat & allergies. should i be concerned(cancer)?

Not too concerned: I expect they are just your lingual tonsils or circumvallate papillae (taste buds). This can occur for many reasons, including allergies. If they remain enlarged particularly if you are a smoker or chew tobacco or drink excessively you should have a medical provider examine you.

Probably not: Bumps on the back of your tongue are common. These papillae grow to different sizes. They can be affected by allergies or irritated causing to enlarge. They may not be associated with your sore throat. Cancer in mouth can be found on the tongue but more common on sides of tongue. Tell your dentist your concern. The doctor can examine site and render a diagnosis.