I have had an asymmetrical mole for over 5 years is it cancerous,also i have dark spots all over my back and my chest ?

Most likely not: Asymmetry (irregular borders) is one of the features which makes doctors worry about a mole being malignant. However, some people do tend to grow irregular moles all over their body which are perfectly benign. If this mole has not changed in 5 years it is most likely benign. However, I do suggest you have it checked and I think you would benefit from routine skin check ups with your doctor.