Boston surgeons successfully performed the first-ever penis transplant in the U.S. earlier this month, according to the New York Times.

Thomas Manning lost his penis to cancer, and the Halifax, Massachusetts, bank courier underwent a 15-hour transplant operation over May 8 and 9, receiving the penis from a deceased male.

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Dr. Curtis L. Cetrulo, a plastic and reconstructive surgeon who served as the Massachusetts General Hospital surgical team’s leader, told the Times that they’re “cautiously optmistic,” calling the experimental procedure “uncharted waters.”

“I want to go back to being who I was,” Manning told the Times from his hospital room, noting that he was comfortable speaking publicly about the transplant in hopes that it would quell the stigma around genital cancer. Though he told the Times he wasn’t quite ready to look at his new organ yet.

Manning’s penile cancer was discovered in 2012, and he underwent a partial penectomy, which left him with what the Times called “a stump about an inch long.” The physical change made life difficult for Manning: “I couldn’t have a relationship with anybody.”

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Previous penis transplants in other countries have been both successful and unsuccessful, with a South African university operation giving a man not only a new organ last year, but also the ability to father a child, according to NBC News. China also reported a transplant – though unsuccessful – in 2006.