If you follow the news regarding advancements in melanoma detection and treatment as much as I do, you may have seen the news story that researchers in Australia have been working on developing a blood test that could identify early-stage melanoma. This is really exciting news because as we all know, the earlier you detect melanoma, the better the odds of long-term survival.
So, let’s clear up something right now… I know there are some people who think that running blood tests can tell the doctors exactly what’s wrong with someone. Some cases, this is true. For example, you can check the levels of iron present in the blood and based on the results, make a definitive diagnosis of anemia. And if a doctor suspects you have leukemia, that can be discovered through a blood test. However for many diseases, including most forms of cancer, a blood test won’t provide this information.
There are blood tests that can provide information about tumor markers present in the blood. It will not surprise you to learn that these are called tumor marker tests. They measure the level of a chemical that some tumors produce. The bad news is that normal cells also can produce these chemicals. The use of these tests as a diagnostic tool causes some controversy as a result. But a doctor may ask for one of these tumor marker tests to help determine what’s going on in a patient and guide next steps. Here are the tests that can be ordered and the cancers that may be present:
- prostate-specific antigen (PSA) for prostate cancer,
- cancer antigen 125 (CA 125) for ovarian cancer,
- calcitonin for medullary thyroid cancer,
- alpha-fetoprotein (AFP) for liver cancer, and
- human chorionic gonadotropin (HCG) for germ cell tumors, such as testicular cancer and ovarian cancer
OK, so we know that even when you’re looking at specific chemicals in the blood, you may not always get an accurate diagnosis of cancer. And there isn’t a blood panel workup that can screen for a variety of different cancers (yet). So why am I excited about the new test being developed Down Under?
This test looks for antibodies that the immune system would create in the presence of melanoma. If you’ve ever had a viral infection like the flu, your body has created antibodies as a result of that infection. Same thing with melanoma, your body recognizes the melanoma cells as an invader and mounts an immune system attack to deal with the melanoma, creating specific antibodies. Now because of the ability of cancer cells to evade the immune system, it doesn’t mean that your immune system can keep up with the cancer. Obviously the immune system, while an incredible feat of nature, isn’t perfect. HIV is a virus that successfully manages to evade the best efforts of the human immune system. And your immune system can sometimes target your own healthy tissue and cause diseases like lupus, IBS, and psoriasis.
OK, so we’ve got these antibodies in our blood as a result of melanoma. How does that translate into action? The researchers screened 245 blood samples, some from melanoma patients and some from healthy volunteers. They were able to identify people with melanoma with 79% accuracy and people without melanoma with 84% accuracy. That’s pretty good but most want to see 90% accuracy before they would say it’s a success. The researchers are next working on a trial with a larger pool of participants to refine the accuracy. According to the team, if all goes well, the blood test could be available in the next 5 years.
That would be great if we could see a level for melanoma antibodies in a standard blood screening, just like you get results for cholesterol, glucose, and iron levels. That would go a long way towards helping people discover melanoma earlier and get lifesaving treatment earlier.
Since my blog is focused on melanoma, I didn’t really talk about the other development that happened earlier this year. A group of researchers developed an experimental blood test to potentially detect cancers of the ovary, liver, stomach, pancreas, esophagus, colorectum, lung and breast. They did this by assessing the levels of circulating proteins in the blood and mutations in cell-free DNA. Basically, they looked at these 8 different proteins and combined that with DNA markers. The test had widely varying rates of accuracy for the different types of cancer and the earlier stages of the cancers had much lower levels of accuracy. So there’s a long, long way to go to get to the point where we could see this deployed in doctors’ offices. But the fact that there is so much research in this area is promising. Maybe not in my lifetime, but maybe someday, discovering you have an early stage cancer by a blood test can be a reality, saving the time you would normally take just trying to get an answer on what’s wrong with you and use that to get treatment instead.