A father’s job is to protect his children — both from themselves and from forces yet unknown.

As a father of three, Marcus Dunn knows there are some tests his children will face that will define their lives, tests they can’t prepare for and likely won’t see coming.

But for all the worry he’s faced through the years guiding his children toward adulthood, it’s the test Dunn himself took in his doctor’s office two years ago that may save the lives of his two sons, who are now in their mid- to late-20s. That was when Dunn learned he had prostate cancer, increasing the risk his sons could one day have it as well.

“Oh they know … you’d better believe they know to get themselves checked out and get tested when the time comes,” Dunn said. “This thing runs in families, so they need to educate themselves and be prepared. I hate to think of it that way, but as their father I’ve got to.”

As an African-American in his 50s, Dunn’s doctor suggested he also have a prostate exam as part of his annual physical, which included a prostate specific antigen (PSA) blood test. It’s a decision that’s come under increased scrutiny in recent years as some urologists and medical associations are at odds about when men, no matter their race, should be tested for prostate cancer and whether or not the PSA test should be used at all.

Dunn was oblivious to the controversy.

“I didn’t know much of anything about PSA tests or prostate cancer,” said the 53-year-old, who lives in Anniston. “I did what my doctor suggested … and I’m glad I did.

The test showed Dunn’s PSA levels were elevated. PSA is a protein produced by cells of the prostate gland, and PSA is often elevated in men with prostate cancer.

The subsequent biopsy discovered cancer cells, but Dunn took his time — nearly eight months — before choosing to have robotic prostatectomy in April of last year.

“I wanted to be informed, to do my homework and to pray on it. It was a hard decision because of all the side effects, and I was worried. This is my manhood, my sex life we’re talking about,” said Dunn. “I decided that I wasn’t gonna let cancer come after me. I was gonna go after it … that’s the way to beat this thing.”

According to the National Cancer Institute, about 16 percent of men will receive a prostate cancer diagnosis in their lifetimes, nearly 3 percent of whom will die from it. And while Dunn and millions of other men believe the PSA test was vital in catching their prostate cancer early, there is a debate taking place within the medical community challenging the testing.

“In the field of urology, it’s extremely controversial,” said Anniston urologist Dr. Lawrence Rosen, who recently attended a conference on PSA testing that stirred emotional reactions from doctors on both sides of the issue. “We have a long history of men for whom the PSA has saved their life and they all had major or minor levels, but the current thoughts are that there are many false positives, meaning that the PSA might be elevated and (the patient) might choose to do a biopsy, only to discover that there was no cancer.”

While the PSA is a simple blood test, the subsequent biopsy — in which roughly a dozen “cores” are taken from the prostate with a needle — is more involved, painful and can lead to side effects such as bleeding, or in some cases, infection or urinary difficulties. In a statement published in May 2012, the U.S. Preventative Task Force found that “ a substantial percentage of men who have asymptomatic cancer detected by PSA screening have a tumor that either will not progress or will progress so slowly that it would have remained asymptomatic for the man's lifetime,” meaning many men can have prostate cancer but may never feel any effects from it.

The PSA test was originally developed as a way to tell whether prostate cancer was returning in men who’d already been treated. Prostate cancer disrupts prostate cells and causes the release of PSA into the blood.

By 1991, PSA testing had become a routine part of yearly physicals in men who showed no sign or family history of prostate cancer. But several factors besides cancer can attribute to an elevated PSA, and its accuracy has caused PSA testing to fall out a favor among many urologists in recent years.

Leading the charge in opposition to recommended PSA testing is Richard J. Ablin, who discovered the antigen that led to the PSA test. In his book, “The Great Prostate Hoax: How Big Medicine Hijacked the PSA Test and Caused a Public Health Disaster,” Ablin blames the medical profession for allowing pharmaceutical companies to play a role in diagnosing the health of men.

“Think of PSA as oil,” Ablin writes, referring to the various drugs used to treat such side effects as erectile dysfunction. “If the test were made irrelevant, an industry would crumble. You don’t have to be a conspiracy theorist to grasp what the stakeholders will do to keep this industry booming.

“There’s no right answer, but the last-ditch defense by the PSA-to-biopsy-to-treatment proponents saying ‘We must do something’ does not engage the issue in a constructive way. It simply uses fear to fuel the prostate cancer industry.”

Yet it’s hard to argue the value of a test many men believe could save their lives.

At 47 years old, Victor Price of Heflin gets a prostate exam and PSA test every year. The only motivation Price needs to be tested now lies in a small family plot just outside of Gainsville, Fla.

“I do it because of my dad,” he said. “If he’d gotten tested sooner, he might still be alive. I don’t wanna make that mistake no matter what some doctors may say. I want to be around for my family. That’s the one thing I learned from dad.”

Martin Price died in 2009 at the age of 77. His prostate cancer went undetected until it spread to his bones. Though Martin and his son “weren’t very close,” Victor watched his father wither away and die in terrible pain from a cancer that, with a yearly prostate exam and PSA test, could have been detected and treated in time. Prostate cancer, by its nature, is slow growing; if caught before it breaks out beyond the prostate, it’s very treatable, either with chemotherapy, radiation or the removal of the prostate.

“Dad didn’t do any of that,” Price said. “I don’t know if he was scared or too busy or just didn’t think it was a big deal, but whatever the reason … he was wrong.”

The American Urologic Association, in a clinical guideline released last year, said men should only consider getting a PSA test between the ages of 55 and 69 if they have signs or symptoms of prostate cancer or have an immediate family history of prostate cancer.

Price had his last PSA test in early April, registering a 0.3 with no signs or symptoms of cancer. He’s spending this Father’s Day in Disney World with his wife and three daughters.

“Testing is the one thing my dad taught me,” he said. “And that’s something I’m grateful for.”