Cancellation of a trademark registration can occur within the first five years of registration for any reason that the mark could have been precluded from registration in the first place. Specifically, that includes: (1) Likelihood of confusion with petitioner's previously used or registered mark, (2) Fraud, (3) Descriptiveness, (4) Genericness, (5) Abandonment, (6) Misdescriptiveness and deceptiveness. However, fair use, trademark misuse, unfair competition, or violation of anti-trust laws are generally not considered valid grounds for cancellation.
Five years after registration, and if incontestability status has been successfully obtained, the mark can no longer be canceled on the basis that the mark lacks distinctiveness or creates a likelihood of confusion with a prior-registered mark. However, the mark can still be canceled on the basis of: (1) Genericness, (2) Abandonment, (3) Fraud, (4) The mark is forbidden, (5) The mark is an improperly used collective or certification mark, (6) The mark disparages or falsely suggests a connection with persons, institutions, beliefs, or national symbols, or (7) The mark is used to misrepresent the source of goods. Since these latter two grounds (6 & 7) appear akin to likelihood of confusion, which is supposed to be ruled out as a ground for cancellation after the five year period, they have been the subject of criticism. In any event, if you are claiming cancellation on the basis of 6 or 7, you will inevitably need to prove something more than likelihood of confusion to succeed.