Tag: preventative medicine

Guardant Health (GH) and Exact Sciences (EXAS)

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March 15th 2024

An article published in NY times on 3/13/24 titled “A Blood Test Shows Promise for Early Colon Cancer Detection” shared news about a blood test for colon cancer screening. 

Let’s look at the results of this ECLIPSE trial published in NEJM: 

This blood test missed 87% of advanced precancerous lesions which makes it less useful in early screening. There is also a trend in the data showing the blood test is less effective in detecting early stage cancers (the sensitivity for clinical stage I colorectal cancer was 55% while and sensitivity for clinical stage I, II, or III colorectal cancer was 81%).

While a colonoscope is able to visualize the precancerous polyps and remove them (performing diagnosis and treatment at the same time), the blood test seems to be detecting cancer but at a later stage. If I were the patient I would do the colonoscope. As a physician I would still recommend patients to get a colonoscopy, only when the patient is resistant to the ideas of performing colonoscopy I will recommend for the patient to get a fecal or blood test. Fecal test is more sensitive and more specific partly due to the sample being closer to the tissue (Per Blue-C trial, the next-generation Cologuard test has a sensitivity of 93.9% for colorectal cancer and specificity of 92.7% in a population of asymptomatic adults 40 years of age or older while ECLIPSE trial is conducted in a population of 45 years or old). 

Now how much promise does it carry for the trial sponsor Guardant Health? It has to be FDA approved first and be reimbursable by insurance companies and government insurance plans such as Medicaid or Medicare and consumer or primary care physicians have to be willing to order the tests. The current major selling point for Guardant health’s blood based screening test is high patient compliance.

Exact Sciences published a trial in NEJM in 2014: in asymptomatic persons at average risk for colorectal cancer, it detected significantly more cancers than did FIT but had more false positive results. This test is called Cologuard with a cost of $581 to $681. Now 10 years later Cologuard revenue is about 2 billions annually with a trend to grow.

Of notice, Epi ProColon test made by a Germany company Epigenomics AG (FSE: ECX) was approved by FDA but was not granted Medicare payment. It cited the criteria for a blood-based screening test need to have both sensitivity greater than or equal to 74% and specificity greater than or equal to 90% in the detection of colorectal cancer compared to the recognized standard (accepted as colonoscopy at this time).

Whole body MRI

Whole-body MRI (WBMRI) is a diagnostic imaging technique that covers the entire body, providing detailed images of multiple organ systems and tissues. While WBMRI is not used as a routine screening tool for the general population, it has specific applications in certain clinical situations. Guidelines for the use of whole-body MRI may vary by country and professional organizations, but here are some common applications:

1. Multiple myeloma: WBMRI is often recommended for the initial staging of multiple myeloma and assessment of treatment response, as it can detect bone marrow involvement and bone lesions throughout the body.

2. Lymphoma: WBMRI may be used for staging certain types of lymphoma, including Hodgkin’s and non-Hodgkin’s lymphoma, and for assessing treatment response.

3. Metastatic disease: WBMRI can be useful for detecting metastases (cancer that has spread) from known primary tumors, especially when the primary cancer is known for producing diffuse metastatic patterns.

4. Bone metastases: WBMRI may be used to detect bone metastases from various primary cancers, such as breast, prostate, and lung cancer, as it provides high-resolution images of bone marrow and surrounding soft tissues.

5. Inherited tumor syndromes: WBMRI can be used for surveillance in patients with certain inherited tumor syndromes, such as Li-Fraumeni syndrome or von Hippel-Lindau disease, to detect early signs of cancer throughout the body.

6. Pediatric oncology: WBMRI may be used in pediatric oncology for staging, treatment response assessment, and surveillance due to its ability to provide comprehensive imaging without ionizing radiation exposure.

7. Inflammatory and autoimmune diseases: WBMRI can be used to assess the extent of certain systemic inflammatory or autoimmune diseases, such as vasculitis, sarcoidosis, and systemic lupus erythematosus (SLE).

8. Skeletal abnormalities: WBMRI may be used to evaluate the extent of certain skeletal abnormalities, such as Paget’s disease or fibrous dysplasia.

It is important to note that whole-body MRI should only be used when medically necessary, as determined by your healthcare provider. The appropriateness of WBMRI will depend on the specific clinical situation, the benefits of obtaining comprehensive imaging, and potential risks or limitations. Whole-body MRI is not recommended as a routine screening tool for the general population due to concerns about overdiagnosis, unnecessary testing, and cost-effectiveness.

However, whole-body MRI has its own limitations: the protocol for whole body MRI is not more effective than targeted protocol for specific part of body, for example, whole body MRI may not substitute cardiac MRI. For some body parts such as lungs, CT could be a better modality. For cancer screening, invasive methods such as colonoscopy and papsmear is unlikely be replaced.

I think this is a very promising technology that may have significant development in the future. It’s possible that eventually, everyone will undergo a whole-body MRI once a year as part of their annual checkup or even several times a year. It’s like what is depicted in science fiction movies – a full-body scan followed by numerous diagnostic results. Of course, for now, it is still quite expensive – costing a few thousand dollars per scan, unless for specific medial reasons it is not covered by health insurance, so not everyone has the financial capability to undergo the procedure whenever they want or as many times as they want.