The most widely reported such incident in recent years was that of Jaycee Dugard, who was freed in 2009 after 18 years of captivity behind the home of a California couple.
In another case, Ryan said last year a 43-year-old man was found and reunited with his mother after being abducted at the age of 2.
More than anything, the three victims need privacy and time with family members, said Elizabeth Smart, who was in the headlines in 2002 when she was kidnapped from her Utah home at age 14 and held captive for nine months.
"I want them to know that nothing that has happened to them will ever diminish their value and it should never hold them back from doing what they want to do," Smart told CNN's "The Situation Room."
The women should not feel pressure to speak publicly about their ordeal, Smart said, adding that time will help them heal. "It's just incredible they are walking away from this horrendous nightmare, alive and safe today," she said.
'We're hoping for a miracle'
Investigators had previously speculated that the disappearances of Berry, DeJesus and another girl, 14-year-old Ashley Summers, may have been connected. Summers' family last saw her in July 2007, when she was 14.
"We did in fact believe there was an association between the Berry case and the DeJesus case as well as the Summers case," said former FBI agent Jennifer Eakin. Eakin is now a case manager at the National Center for Missing & Exploited Children, which in 2008 held a comprehensive review of the cases with the FBI and Cleveland police.
Now the Summers family is hoping that the Cleveland investigation will yield information about Ashley, her aunt, Debra Summers, said.
"We're hoping for a miracle," she said.
Anderson, the spokeswoman for the Cleveland FBI office, said investigators will question the three women found Monday in the hope that they know something about Summers' disappearance.
Of the three brothers arrested, Ariel Castro was the only one to live at the home where the three women were apparently held, police said. The others lived elsewhere in the city.
Their uncle, Julio Castro, told CNN's "Anderson Cooper 360" on Monday that his family had grown up in the same west Cleveland neighborhood and knew the Georgina DeJesus family.
Julio Castro told CNN's Martin Savidge on Tuesday that family members were "surprised" over the developments.
"Shame on you," Julio Castro said, when asked what he would say to his nephews.