I have non displaced 5th metatarsal fracture and doc said to put cast for six weeks. is there any other way in which fracture can heal without the?

Proper Treatment: Casting a 5th metatarsal fracture is the best conservative treatment option. Another option would be a removable cam walker (boot), but it is not as stable/predictable as a cast. There is a strong tendon attachment to the base of the 5th metatarsal, and you must keep the entire foot/ankle immobilized to keep that tendon from displacing the fracture. It should heal in 6-8 weeks.

Let me explain: You have to immobilize the fracture to give it some time to heal, you could achieve this by cast or possibly by camp boat which work like a cast but you can take off for shower, this way you run the risk of the fracture may not heal or delayed healing.