Dr. Kevin Most: Blood tests for cancer, screenings and eclipse eye safety
Last week we touched on Eddie Olczyk and his battle with Colon Cancer at the age of 50. The reason to discuss that topic was to keep everyone informed of a changing trend in colon cancer and to also remind everyone about the importance of screening for colon cancer and really for all cancers where we have early detection options. We touched on his case specifically as he had just reached the age for screening when his cancer was diagnosed and it appears it was beyond the simple superficial stage as surgery and chemotherapy were reported as his treatment.
We have discussed the importance of screen as well as the controversies around screening for cancer of all types. There have been changes in recommendations often and it adds to the confusion which is troublesome. The reason for increased clarity is that we need the individual to be aware of what should be on their health checklist.
We need individuals to be more active in their health to prevent or identify illness earlier versus waiting for illness to occur and then hope we have the proper treatment available. The controversy has been noted in Prostate Cancer and the use of PSA blood testing, Breast cancer and the timing and frequency of mammograms, Lung cancer and who should be receiving CT scans after a smoking history and as we discussed last week the increasing trend of colon cancer occurring before the screening is even recommended. As doctors we are often trained to follow one recommendation only to have it change dramatically, leaving us with the change in practice pattern as well as the duty to educate our patients about the change.
The screening we use can be expensive, difficult to find and often an overall hassle for the patient. Because of these reasons screening is often put off, neglected or flat out refused by patients. The overall goal of any screening is to identify patients early in the disease process which allows for less invasive treatment and, better outcomes, lower cost and less disruption to the patient that extensive disease would cause. We balance that with the yield of the screening as well as the cost of screening. With all screening we may find what we call a false positive. That is a test that comes out as positive when in fact the disease or condition is not present. The false positive can cause anxiety as well as unnecessary test or procedures.
We study all screening processes and try to advance on them. Take Breast Cancer for example, the days of a simple mammogram on film are long gone, we now have digital images that can be manipulated and magnified, no longer with a handheld magnifying glass, we have MRI imaging which allows for 3 dimensional identification of tumors versus the single plane we used to have. This is called tomosynthesis, and during this multiple images are taken of the breast and then reconstructed into a 3 D picture. In lung cancer the yield for using a chest x ray to capture a lung cancer was low and often when noted too late to act on. Now we have screening using low dose Ct scans for individuals between 55-80 years old who had a 30 pack year history and have quit within the last 15 years. This again has changed dramatically since I was in residency. Each of the changes hope to detect cancer early and allow for extended life with less invasive treatment.
So hopefully that gives you a little insight into the background of screening.
Last week a study came out that hopefully shows the next generation of screening and how the research and advancement of medicine can have a huge impact in lives. The exciting news is that there have been great advancements in using a simple tube of blood to identify cancer in early stages. We have had the ability to do blood tests on advanced cancer and use the level of these tumor markers to assure us of the treatment or identify a treatment failure. This study coming from researchers at Johns Hopkins, identified DNA from tumors in the circulating blood and were able to identify it in early stage cancers. , They found this DNA in stage 1 and stage 2 cancers using this blood test. What they did is take 138 patients who had stage 1 and 2 cancer and ran the blood test looking for this DNA change. They were able to identify it in 86 of 138 patients. Using this technique you had patients with clearly diagnosed cancers and then ran the blood test and got the results they found. Remember above when we discussed the impact of “false positives”? Well they also ran the test on 44 healthy individuals and it did not find this DNA in those individuals.
The interesting thing is that they ran this tests on patients with different types of cancer, including colon, lung, breast and ovarian. The success of identifying the patient with the blood test ranged from 60-70%. The tests are essentially “liquid biopsies” and are being studied in many hospitals and universities around the world. This study however is the first to show such promising results. When we look back at last week’s discussion and Eddie Olczyk, this test actually identified stage 1 colon cancer with a 70% accuracy. Blood tests like this can be game changers. Consider a simple blood test that is done every year that could act as an early detection for lung cancer, colon cancer, breast cancer and ovarian cancer. We would have people lining up for the tests instead of the constant prompting and rule changing guidelines we have now.
The thought of a simple blood draw eliminating the need for mammograms would have women lining up as fast as they could. Being told you have your choice between a blood test or a colonoscopy could lead to more psychiatric evaluations but again the line would be out the door. One of the bigger impacts will be on the cancers that are often identified to late such as ovarian cancer, this is often diagnosed well after it has advanced.
This has the potential to be earthshattering. The next steps are to look at other cancers and start clinical trials to validate the study as well as how can the process be commercialized beyond the research lab. This technology may end up being one of the greatest medical discoveries of the century.
It may be the study that has the biggest impact not only in the health of individuals but also allow us to see a large decrease in the cost of health care. Think about the cost of surgery and chemotherapy being eliminated for many cancers, the pain and suffering from those procedures as well. We know the life expectancy in every cancer is extended when we find the cancer in stage one. Watch for more on this as we know it will advance much more quickly based on the results of this study.