Will breast-sparing surgery affect the look of my breast?

It can(better/worse) I agree w/dr. Hoepfner's excellent answer. In addition...Oncoplastic surgery describes applying the same principles of breast surgery that plastic surgeons use without compromising cancer treatment. Using these techniques, we can often "hide" scars in natural skin folds. Some women may even opt for simultaneous breast reduction and/or lift and may actually look better after cancer surgery.
Ask your surgeon. Most surgeons who perform this surgery do so to preserve as much healthy breast tissue as possible, and preserve the cosmetic nature of the remaining breast tissue. It can depend on where the tumor is located, where the incision is made, and how much tissue needs to be removed to remove the tumor. Be sure to review the plans with your surgeon before the operation.