Hi,
I would not recommend doing either a) or b) above.
1. For within patients analysis only, one could analyze Laterality (left vs right) as the main effect. You could include Sex as a covariate.
2. Again for within patients, you can do separate analyses for all patients with left sided tumors and right sided tumors.
3. If you want an across subject (controls and patients), then you could include laterality as a covariate.