I had throat cancer the results were a complete laryngectomey im just curious how long can you have this and be undetected is 7 years possible?

Depends: Most cancers take years to develop and a good part of that time the lesions are undetectable. Once the tumor reaches the size of about 1.0 cm if may become clinically apparent. Depending on the growth rate of the tumor it may have many years for the lesion to grow from less than 1.0 mm to the 1.0 cm size.

Short or long time: Some cancers take a long time to develop. Some cancers are very aggressive and can grow quickly. Laryngeal cancer is usually squamous cell carcinomas which grow fairly quickly. Each cancer is different and it is possible but not likely you could have had an early undetectable cancer 7 years ago.

Since you had: A complete laryngectomy you probably had an advanced cancer, you probably had radiation and chemo also, yes it's possible. They're finding out now that throat cancers caused by a virus are more easily curable.