Study Overview: This study tests the safety and effectiveness of a drug called T-DM1 in treating HER2-positive salivary gland cancer. T-DM1 is a combination of trastuzumab (an antibody) and DM1 (a chemotherapy drug). It targets HER2, a protein found in some cancers, to help kill cancer cells more directly. The study includes T-DM1 with radiation and chemotherapy after surgery, and for some, T-DM1 alone for a year. Key Points:

• Participation involves 1-year treatment and 3 years of follow-up visits.
• This study includes radiation, chemotherapy, and T-DM1 therapy.
• About 55 people are expected to participate, with Genentech providing the drug.

Eligibility: Participants must have specific stages of salivary gland cancer, be 18 or older, and show HER2-positive results. They must provide tissue and blood samples and have normal organ function. Women must pass a pregnancy test, and both men and women need to use contraception if of childbearing potential. Exclusions: Those with different cancer stages, prior treatments for head and neck cancer, or uncontrolled illnesses, among other factors, cannot join. This study is not FDA-approved for this cancer type but is approved for others, like certain breast cancers.