Day after day, Catholics return from sobering hospital visits and type these terms into online search programs -- "cancer" and "patron saint."

This leads them to St. Peregrine Laziosi, a 13th century Italian monk who spent his life serving the sick and destitute. Biographers note that, at age 60, he was mysteriously cured of a gangrenous growth on his right leg.

With additional computer-mouse clicks, cancer patients find prayers like this: "St. Peregrine, whom Holy Mother Church has declared patron of those suffering from cancer, I confidently turn to you for help in my present sickness. I beg your kind intercession. Ask God to relieve me of this sickness, if it be his Holy Will."

Members of ancient Christian churches grow up knowing about their own patron saints, as well as saints linked to their parishes. It's natural for Catholics to identify with saints -- like St. Patrick in Ireland -- linked to their homelands.

But there are times in life when it's natural for believers to seek "companion" saints to enter their prayer lives, said Father James Martin, author of "My Life with the Saints," a commentary on the role of saints first published in 2006.

"Even if you have no pre-existing ties to St. Peregrine, you are going to pray to him for his intercessions when you learn that you have cancer," said Martin. "That's just one of the many ways we get connected to saints at different times in our lives. Sometimes these connections are logical and sometimes they are mysterious. … 

"I tell people that when they find themselves being drawn to a particular saint, it's probably because that saint is already praying for them. In the end, this is all about the Holy Spirit and God's providence."

 It's hard to say why some saints are more popular or famous than others. The Catholic website Aleteia ("truth" or "disclosure" in Greek) recently published a feature entitled, "The top 12 saints according to Google searches."

The top online saint was St. Vincent de Paul of France, which could indicate that many people were looking for St. Vincent de Paul thrift stores. The second saint was St. Mary, the mother of Jesus -- whose online ranking may have been complicated by the myriad names she has been given over the centuries, from theological titles such as St. Mary Queen of Heaven to cultural names such as Our Lady of Guadalupe.

"It's hard to imagine that Mary could be ranked No. 2 on any list. … Mary is everywhere in the life of the church but, frankly, Catholics do tend to forget that Mary is a saint," noted former Newsweek reporter Kenneth Woodward, author of "Making Saints: How the Catholic Church Determines Who Becomes a Saint, Who Doesn't, and Why."

It was also hard to imagine St. Francis of Asissi in the fourth slot in this search-engine list, since "it seems like he's the saint for everybody, because he's just so loveable," said Woodward. "When it comes to saints, No. 1 is Francis of Asissi and there are no seconds.”

There was never one specific point in history when the concept of "patron saints" was born, he said, because the veneration of "the saints has been there from the beginning" of Christianity.

However, it did become normal in the Middle Ages for guilds and trades to find logical saints to adopt -- such as St. Peter becoming the patron saint of fishermen. Nations and cities also began claiming their own patron saints.

"There's that saying that all politics is local," said Woodward. "Well, saints can be local, too." Ironically, many missionaries became saints when they were martyred, and then "their converts would later claim them as their patron saints. … That happened over and over during church history."

Some heroes of the faith are quickly hailed as saints -- St. Pope John Paul II and St. Mother Teresa of Calcutta made the Aleteia list -- while others are recognized centuries later. The key, he said, is "not the mechanics of the process" but the story of a remarkable individual's life and faith and how believers come to identify with it.

"We are talking about the transformation of a life into a text," said Woodward. "Then that story inspires people's faith and they keep passing it on."