Wilson, 58, has taken a leave from the Broadway play in which she was starring, Larry David's Fish in the Dark, to have the procedure, which was done last week. She says she expects to make a full recovery.
Wilson says she only caught the cancer because she sought a second opinion.
"I have had an underlying condition of LCIS, (lobular carcinoma in situ), which has been vigilantly monitored through yearly mammograms and breast MRIs. Recently, after two surgical breast biopsies, PLCIS (pleomorphic carcinoma in situ) was discovered," she says in a statement. "I was relieved when the pathology showed no cancer.
"However, a friend who had had breast cancer suggested I get a second opinion on my pathology and my gut told me that was the thing to do," she continues. "A different pathologist found invasive lobular carcinoma. His diagnosis of cancer was confirmed by, yet, another pathologist. I share this to educate others that a second opinion is critical to your health. You have nothing to lose if both opinions match up for the good, and everything to gain if something that was missed is found, which does happen. Early diagnosis is key."
Wilson also thanked her husband, Tom Hanks, as well as family, friends and her doctors for their support.
"I am the beneficiary of advances in the field of breast cancer and reconstruction. I am getting better every day and look forward to renewed health," she tells People. "I hope this will encourage others to get a second opinion and to trust their instinct if something doesn't 'feel' right."