According to a recent study the regular test for prostrate cancer screening may not be accurate in the case of obese men. The study, published online Friday in the journal BJU International, suggested that men who were obese were likely to suffer more harm than benefit from treatment for prostrate cancer which could leave them more vulnerable to the disease.

Dr. Stephen Freedland, an associate professor of urology and pathology at the Duke University Prostate Center, and an author of one of the studies said, "Obese men are more likely to be diagnosed with an aggressive form of the disease."

This reasoning was based on the fact that blood tests look for elevated levels of the protein prostate-specific antigen (PSA), which indicate an increased cancer risk and often these are not as reliable in the case of obese men.

Freedland said, "Our assumption is that these men have more blood volume, so PSA gets diluted. By the time obese men get to elevated levels, the cancer is more advanced."

When the PSA reading is 4 or higher, prostrate cancer is suspected. Currently men who are 50 years and older are recommended annual PSA screenings, which assess their possible risks and benefits. "I'm not sure that we should check obese men more often," Freedland said.

"But we should have a higher [PSA] index of suspicion of what is not normal -- 3.4 rather than 4; for really obese men, 3.2."

Another study on similar lines was conducted by Duke, which found excess weight influenced the outcome of surgery for prostate cancer. A BMI of 35 or more in men made them nearly 60 percent more likely to have a recurrence of the cancer as compared to thinner men.  

Dr. Jayakrishnan Jayachandran, a urology oncology fellow at the Duke Prostate Cancer Center said the reason is "the difficulty of operating on obese men in general. The prostate is a narrow thing to operate on, and when there is a big wad of fat in your way, if the abdominal wall is thick, it becomes a technical issue."

This basically means that not all the cancer can be removed and that results in a reoccurrence after some time. "The only thing we can think of is that when you operate on obese people, you have to be more careful," he said.

Jayachandran added, "We are not screening these obese men effectively and are not doing as good a job surgically as could be done."

The U.S. Preventive Services Task Force have recommended that doctors stop screening men who were 75 or older for prostrate as they were likely to have a life expectancy of less than ten years, which was less than the time prostrate cancer would take to kill them.

Dr. James Mohler from Roswell Park Cancer Institute said that the PSA blood test developed at Roswell Park had shown a sharp decline in prostrate cancer mortality.

"We all know that every 75-year old does not enjoy the same health and the same life expectancy. It's naive to think that you can simplify something to this level.” He added that “PSA has allowed us to decrease to tumor volumes like this that are sometimes curable, to small little nodules that are almost always curable."

Timely screening can predict whether you have a slow growing tumor or an aggressive one.  A low PSA level for years that rapidly rises could suggest an aggressive tumor though the only way of knowing for sure is by performing a biopsy. Though many older men may not want a biopsy the option should be given to them.

Dr. Mohler continues, "They probably need to know whether they have prostate cancer or not, because if they have an aggressive prostate cancer, they're probably going to choose to be treated. What you don't want to do is deny the healthy 74-year-old curative treatment if they need to be cured; if they are found to have an aggressive cancer."