Can spinal mri see lungs? or even lung cancer?

Not well: Lungs not well defined on mri. Spinal mr is limited mainly to spine and does not cover the whole area of chest.

Not really: Mri's are geared to see specific portions of anatomy, such as bone, soft tissue, vessels, etc. While other structures can be visualized with a spinal mri, it is inadequate to make a diagnosis. If something is suspected, any radiologist would immediately recommend another imaging study to better visualize the area or concern.