A research report released last evening (and which will be presented at the annual meeting of the American Society of Clinical Oncology in early June) is bound to raise hopes that we have—at long last—found a test that can effectively diagnose ovarian cancer when it is in its early stages and most curable.
The problem is that ovarian cancer is usually diagnosed at a later stage when it is more difficult to treat and cure. Finding a test that will detect ovarian cancer early when it is treatable and curable has been referred to by many as the “holy grail” of cancer early detection.
But if we are to learn anything from the recent prostate cancer screening controversy, it is that we must proceed with caution before jumping into the fray with both feet. Otherwise, we may find ourselves 20 years from now asking the same questions about this ovarian cancer test that we are now asking about the real value of the PSA test.
In the past, ovarian cancer has been called “silent” since so many women were diagnosed late in the course of the disease, ostensibly because there were no typical symptoms.
But that really isn’t always the case.
Recent research has reminded doctors and patients alike that women with ovarian cancer frequently have symptoms for many months before being diagnosed. These symptoms, such as difficulty eating, bloating, urinary frequency and vague abdominal discomfort are common and frequently dismissed or attributed to other less serious conditions. Maintaining increased awareness and vigilance regarding these symptoms could lead to earlier diagnosis and more effective treatment according to experts and advocates.
Looking for an effective test that could screen for ovarian cancer and find it early has been a major research goal in medicine for many years. Sadly, for women at average risk, we simply haven’t been successful in finding one. There have been some false starts, but nothing that has withstood the test of time and proven to be truly effective in singling out early ovarian cancer when examined in large clinical trials.
The current study used a well-established and widely available blood test called CA-125. It is a protein (called a “tumor marker”) that circulates in blood and is elevated in patients with ovarian cancer. Unfortunately, it is not absolutely specific for ovarian cancer, which means that it can be increased in other cancers and conditions such as pregnancy, benign fibroids and ovarian cysts among others.
The logic of the research is reasonably straight forward—so much so that it is interesting that it has taken us this long to get to this point. The theory is that if the CA-125 level in the blood increases, then the woman is more likely to have ovarian cancer. The problem is that the test also increases in other conditions, and sometimes for reasons that no one can find out.
This is not the first time CA-125 has been used in a research study to find out if it can work as a tool to screen for ovarian cancer in women at average risk. In prior studies, the test did diagnose ovarian cancer in some women, but also missed ovarian cancer in other women and led to surgery in some women where no cancer was present.
So, bottom line, past research has suggested that this test—although useful in the diagnostic workup of an existing ovarian mass or to follow a woman with ovarian cancer—is not believed to be sufficiently accurate to be recommended for routine use by large numbers of women at average risk to detect early ovarian cancer.
In the current study, the investigators measured CA-125 blood levels annually from about 3200 women between the ages of 50 and 74. Based on the age of the woman, the level of the CA-125 test, and if it changed over time, they determined which women were possibly at higher risk for ovarian cancer. They referred those women to a gynecologic oncologist for further evaluation. That doctor then decided whether or not the woman needed surgery for possible ovarian cancer.
85 women over the course of the study were referred for evaluation. Eight had surgery, and of those 3 had early stage ovarian cancer, 2 had borderline ovarian cancers, and 3 had benign ovarian tumors. According to a press release, two women had borderline ovarian cancers that were not picked up by the screening test.
At first glance, these are exciting results, in that 3 women had their cancers diagnosed at an early stage when the treatment was simpler and the outlook excellent for a full recovery.
To the authors’ credit, they were cautious in their assessment of the impact of these results. As noted in the same press release mentioned above, one of the lead scientists on the study was noted to observe that “while encouraging, the findings are neither definitive, nor immediately practice-changing…A large randomized prospective screening trial still needs to be conducted.”
Those comments are very important in putting this study into perspective.
I have no doubt there will be reports in the press and on the web stating this research shows that CA-125 is a great test to detect ovarian cancer early. Unfortunately,
prior studies simply haven’t supported that notion for women at average risk.
For example, I came across one study reported on our website in June of 1999 where 22,000 women were part of a study somewhat similar to the one currently reported. In that trial, women were randomly assigned to either no CA-125 test or having the test done every year for three years.
It turned out in that study that there were numerous times the CA-125 was “false positive”, which means the test was elevated but there was no cancer. Some women who were part of the “tested” group developed ovarian cancer that was not picked up by the blood test.
That said, the women diagnosed with ovarian cancer who underwent screening lived about 6 years after diagnosis, while women who were followed without testing and developed ovarian cancer lived about 3 ½ years.
The bottom line of that research was that the test was simply not sufficiently discriminating to be of benefit when used by millions of women. There were too many women who underwent surgery because of the test where no cancer was found and too many women where the test did not detect cancer to make it worthwhile in reducing deaths from ovarian cancer.
So before we get too excited, let’s take a step back and realize that we still have a long way to go before we have an effective screening test for the early detection of ovarian cancer in women at average risk. More studies need to be done, and in fact the authors of the current report stress that they plan to move forward with those studies, including examining other tumor markers to see if they help improve the results of the current program.
We have a tendency in this country to hear news about “new science” and believe that it provides all of the answers. We tend to discount the limitations of our science and knowledge, especially when it comes to making a devastating cancer curable. Such has been the case with prostate cancer over the past 20+ years, where it has taken us that long to find out that the PSA test—although it may prevent deaths from prostate cancer—may not be as perfect as we once thought.
Let’s not make the same mistake with ovarian cancer. Is there reason to be encouraged? Absolutely. But there is still a long road to travel before we validate the concept that CA-125 is in fact the answer to our prayers for the early detection of this devastating disease.
So the research must continue to get the right answers, and find out if this test really works in helping to save lives from ovarian cancer while not harming women in the process with unnecessary surgeries, anxieties and unanswered questions as to why a test is elevated when no cancer is detected.
In the meantime, become educated about the symptoms of ovarian cancer and know what to do if you develop new symptoms that don’t go away. That still remains our best line of defense. It’s not perfect by a long measure, but it is still an important part of taking care of your health if you are a woman.