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Myth: Exposing a tumor to air during surgery causes cancer to spread.

Reality: Surgery doesn't cause breast cancer and it doesn't cause breast cancer to spread, as far as scientists can tell from the research so far.

Your doctor may find out during surgery that your cancer is more widespread than previously thought, however. And some animal studies have shown that removing the primary tumor sometimes enables metastatic cancers to grow, but only temporarily; this has not been demonstrated in humans.

Next: Myth: Breast implants can raise your cancer risk.