Can a one year lease be broken if the unit being leased is infested by roaches?

If you were not the cause and they did not exist when you made the lease, yes because you are not getting what you contracted to pay rent for.

You should notify the landlord in writing, keeping a copy of the writing for your records, that the rental unit is infested with roaches, and that you intend to vacate the unit if the problem is not addressed in 10 days. Alternatively, you could withhold rent to the extent of money is used to address the problem yourself, after giving the landlord written notice of an opportunity to correct the infestation.