The defender shot to fame under Jose Mourinho when he was promoted from the youth team at the age of 18, but amid injuries and management changes, spent much of the last two years in the stands.
"I was very close to joining Roma and they were the only Italian club I'd have accepted with enthusiasm, because the new management gives space to young players," Santon told the Corriere dello Sport.
"Roma enquired after me several times, proposing a loan deal, as did Newcastle. With three days of the transfer session left, the British club made the right proposal to Inter.
"I was very glad, as otherwise I risked staying at San Siro and sitting in the stands for the whole season.
"It was over at Inter. My adventure had concluded and I would not have had the opportunity to prove myself again."