A "Double Whammy" for Detecting Prostate Cancer in African American Men
Because of the groundbreaking research of urologist Ted Schaeffer, M.D., Ph.D., scientists know that prostate cancer is more aggressive in men of African descent than it is in Caucasian men. They also know, thanks to Schaeffer, that not only is cancer more aggressive in these men; it's harder to find. Schaeffer discovered that African American men are twice as likely as Caucasian men to have aggressive cancers develop in the anterior area of the prostate.
They discovered that not only are the cancers different, but the difference is potentially dangerous.
"If you think of the prostate as a house, and the rectum as the basement, we come up through the basement with the biopsy needle," says Schaeffer. In most Caucasian men, prostate cancer is located in the posterior part of the prostate, "immediately adjacent to the rectum — so it's basically on the first floor. But in African American (AA) men, aggressive cancers are hiding up in the attic, which is much more difficult to sample on an ordinary prostate biopsy. For this reason, many AA men are misclassified as having indolent disease — they are falsely reassured that their cancer is not the kind to worry about — and their diagnosis of aggressive cancer is delayed."
Building on this work, Schaeffer has explored whether these cancers themselves are different — not just in location, but in their molecular makeup. In other words, "are the fundamental building blocks different in tumors that begin in the posterior location?" To find out, Schaeffer and colleagues examined the genetic codes of more than 100 prostate cancers from both anterior and posterior locations, in both AA and Caucasian men. (Caucasian men can develop anterior tumors that are aggressive, but they are more common in AA men.) They discovered that not only are the cancers different, but the difference is potentially dangerous.
"We found that these anterior cancers make less PSA than the posterior tumors do, and that anterior cancers are less dependent on male hormones for their growth than posterior tumors are. This was true in men of both races, but had the strongest association in AA men." The problem, Schaeffer says, is that "we use PSA levels as a screening tool to look for cancers. So that this may be a 'double whammy' for men with anterior cancers: First, anterior cancers are already harder to detect with traditional prostate biopsies. Second, if they make less PSA, men with these tumors may not be offered a biopsy at the earliest possible stage," because a doctor might look at the PSA number and think all is well.
"We don't yet have a biomarker that is capable of specifically picking up an anterior tumor, but this is certainly a dream of mine," Schaeffer adds. "However, the advent of MRI-ultrasound fusion biopsies shows significant promise in picking up these hard-to-find cancers." Schaeffer believes that all men who have had a negative prostate biopsy should undergo an MRI scan, to make sure there isn't an anterior tumor lurking in the prostate's attic. But "men of African descent with an elevated PSA may want to consider getting an MRI as a first step."