Can a liquid biopsy detect AKL-positive NSCLC at 62?

Question

Hello doctor,

My dad is 62 and was recently told he might have ALK-positive non-small cell lung cancer after a CT scan showed a 1.25-inch mass in his left lobe. The pulmonologist mentioned something called a “liquid biopsy,” or blood test, to check for mutations, but we are a little confused about how this differs from the regular tissue biopsy they have already scheduled.

His platelet level is below normal at 98,000, and the doctor mentioned that there is a risk of bleeding from the procedure with these figures. According to one of his friends who is working in the laboratory, a blood test for detecting mutations for lung cancer can be used to identify ALK gene changes without any procedure at all.

My dad also has COPD, and his FEV1 is around 58%, which makes any invasive procedure riskier. He is also on blood thinners for a heart stent that was placed last year.

Can a blood biopsy reliably detect ALK fusion in lung cancer, and is it accurate enough to start targeted therapy like Alectinib or Lorlatinib without doing a tissue biopsy at all? And how long do results usually take, and is it generally covered?

Please advise.

Thank you.

Answer 1

Hello,

Welcome to icliniq.com.

Thank you so much for sharing your concern with me.

From what you have described, a mass in the lung measuring around 1.25 inches with suspicion of ALK (anaplastic lymphoma kinase)-positive non-small cell lung cancer raises an important question about how best to confirm the mutation safely, especially in a patient who has COPD (chronic obstructive pulmonary disease), reduced lung function, low platelets, and is taking blood thinners.

In most cases, tissue biopsy is regarded as the standard diagnostic procedure used for confirmation and mutation analysis for lung cancer. It provides the lab technician with a direct access to the cancerous cells and performs further analysis. Nevertheless, there are some cases where it may be better to look at other methods of diagnosis because of the bleeding risk.

A liquid biopsy is a blood test that looks for tiny fragments of tumor DNA (deoxyribonucleic acid) circulating in the bloodstream. These fragments can carry mutations such as ALK gene rearrangements.

The advantage is that it only requires a simple blood sample and does not involve procedures like bronchoscopy or needle biopsy, which can carry some bleeding risk in someone with platelet counts around 98,000 or in patients on blood thinners.

In clinical practice, I have seen patients with similar concerns where liquid biopsy was used first to obtain mutation information while planning the safest approach for tissue confirmation.

If a liquid biopsy detects an ALK rearrangement, that result is usually considered reliable, and oncologists may start targeted therapy such as Alectinib or Lorlatinib based on that finding. The limitation is mainly with negative results.

Sometimes tumors do not release enough DNA into the blood, so the mutation may not appear in the test even if it is present in the tumor. For that reason, if the blood test is negative but clinical suspicion remains high, doctors still try to obtain a tissue biopsy later when it is safer.

The turnaround time for most liquid biopsy panels is usually about one to two weeks, depending on the laboratory performing the analysis. Many tertiary cancer centers now use these tests routinely, though coverage depends on the healthcare system and insurance policy.

In many regions, they are increasingly supported because they help guide targeted treatment decisions when tissue sampling is difficult.

I hope it helps with your query.

Thank you.