TOM CRUISE’s recent weight loss has sparked concern for his health, and now The ENQUIRER can reveal that the superstar is threatened by a terrifying cancer nightmare!

The hunky actor, who’s still reeling from his divorce from Katie Holmes, lives with the knowledge that he could die from the same scourge that claimed the life of his father at age 49, say sources.

Official documents, obtained by The ENQUIRER, confirm the chilling concerns of the father of three – who’s already been examined by a top cancer specialist.

“Tom turned 50 in July, and that’s a year older than the age his dad died,” said a source close to the “Jack Reacher” star. “With a young daughter to worry about, he has to be thinking about his mor­tality.”

According to the death report examined by The ENQUIRER, Cruise’s dad Thomas Mapother III died of “metastatic rectal carcinoma” on Jan. 9, 1984.

TERRIFIED by the sight of his dying father, Cruise began a desperate health regimen that in­cluded a physical exam every two weeks, revealed a biographer.

In 1994, Wensley Clark­son, author of “Tom Cruise – Unauthorized,” told The ENQUIRER: “The death of Tom’s father left the young ac­tor fearing he could eventually suffer the same illness.

“Tom’s concern with his health made him sensitive to the smallest ailment. He has a medical checkup at least twice every month of the year.

“He won’t touch fatty foods. And he began drink­ing large amounts of water with every meal after one doctor told him ‘flushing out’ his body after eating would prevent cancer.”

In 1989, five years after his father’s passing, the then-27-year-old actor consulted a cancer specialist at Cedars-Sinai Medical Center in Los Angeles.

At the time, Dr. Michael Engle­berg confirmed he examined Cruise but didn’t disclose details of what was involved.

The news was good. “He’s 100 percent healthy,” declared the physi­cian.

Tom lived with his mother, Mary Lee, after his parents divorced in 1974, but the memory of visiting his physically abu­sive dad on his deathbed left a deep impression in the Hollywood heartthrob’s mind.

“When I saw him in pain, I thought, ‘Wow, what a lonely life,’” said Cruise. “It was sad.”

Tom’s dad was a relatively younger victim for rectal cancer, because the chances increase mark­edly after the age of 50. Patients with a familial risk – those who have two or more close relatives with colorectal cancer – make up approximately 20 percent of all patients with colorectal cancer.

That puts the “Mis­sion: Impossible” star – and dad to 6-year-old daughter Suri – right in the crosshairs of the dreaded disease, according to doctors who have not treated him.

Dr. Joel Feinstein, a gastroenterologist from Los Angeles, told The ENQUIRER: “If a person has a father who was diagnosed with colorectal cancer, he has two to three times the risk of getting the dis­ease as the general population.

“In its early stages, it is a highly curable form of cancer. But once it has metastasized, which occurs in over 25 percent of the cases we see, the prognosis is poor. Once the cancer has spread to other organs of the body, the patient, on the aver­age, lives less than a year.”

Dr. Jerome Spunberg, a top radiation oncologist in West Palm Beach, Fla., agreed, saying: “In my opinion, Tom is at an increased risk of developing  rectal cancer because his father died from the disease.”

And Dr. Walter Gaman, a family physician with Healthcare Associates in Irving, Texas, added: “It’s a very serious type of cancer and does spread easily.”

Colorectal cancer is the third leading cause of cancer-related deaths in the U.S. and is ex­pected to kill 51,690 Americans this year alone, according to the American Cancer Society.

While Cruise appears to be in good health, friends say they became concerned when he stepped out in November looking surprisingly gaunt.

Tom’s family had previously voiced concerns when he quickly dropped 15 pounds after Katie Holmes filed for divorce in June.

“His clothes just hang off him,” a source said at the time. “I don’t think he’s looking after himself.”