To avoid this unnecessary panic, we must first understand what exactly are pulmonary nodules? With the popularization of CT and physical examinations, more and more people are discovering that they have pulmonary nodules during examinations, and the age of onset is getting younger and younger. When many people see the test results, their first reaction is "lung cancer." Research shows that pulmonary nodules and "lung cancer" are not the same thing. At this stage, about 20% of healthy people have pulmonary nodules.

What are pulmonary nodules? In fact, nodule is just a descriptive word in imaging, not the nature of the lesion, which means it is not a medical diagnosis! In imaging, chest CT examination finds round-like lesions with increased density less than 3cm in diameter are usually described as nodules, with diameters less than 1cm called "small nodules" and less than 0.5cm called "micronodules".

But this does not mean that "nodule patients" can sit back and relax! Because some patients with pulmonary nodules may indeed be lung cancer patients. Therefore, what everyone is most concerned about, and what doctors have to do, is how to identify whether the nodules are benign or malignant, and then give corresponding diagnosis and treatment suggestions.

Figure 1 Pulmonary nodules

“Looks” different

Pulmonary nodules can be divided into three types

Although they are all called pulmonary nodules , but according to their different “appearances”, pulmonary nodules can generally be divided into three types: pure ground-glass nodules, partially solid ground-glass nodules and pure solid nodules.

The first type is Gross glass nodule (GGN) or ground glass shadow (Gross glass, opacity, GGO)

The so-called ground glass is just like in our daily life The frosted glass you see is like a layer of obstruction, but you can still see the lung tissue behind the glass.

Figure 2 Pure ground glass nodule

The second type of nodule, Solid Pulmonary Nodule (SPN)

From the CT image, The nodules are highly dense and completely opaque, and the black lung tissue can no longer be seen. This is a solid nodule.

Figure 3 Solid nodule

The third type, mixed gross glass nodule (mGGN)

This type of nodule In the "middle" of the first two, it appears as a mixture of ground glass and solid nodules on CT images, and there is also a solid component in the ground glass shadow.

Figure 4 Mixed ground-glass nodules

Three types of nodules, which may be benign or malignant. Benign ones include spherical pneumonia, tuberculosis, benign hamartoma, and fibroplasia. Malignant nodules often have some special symptoms that will be written on your CT report sheet, such as "burr sign", "lobulation sign", "pleural traction sign", "microvascular sign", "spinous process sign, etc."

One of the golden rules for treating diseases is "early detection, early diagnosis, and early treatment", especially for cancer! How to make a more accurate diagnosis? This is also a matter of concern to everyone.

Case: It is difficult to distinguish between "good and evil", so "lung cancer autoantibody testing" is required

51-year-old Li, male, was found to have nodules in the lungs and chest during a physical examination in 2020 CT: Ground-glass nodule in the right lower lung, about 7 mm in size, with low-density shadow within it. Then he went to our hospital for treatment. The results of the first CT scan and the follow-up CT scan after 3 months could not distinguish whether the nodule was benign or malignant.

It is difficult to evaluate the nature of the nodule with CT alone, and the patient himself is also quite anxious, so he was advised to do a blood test for "lung cancer autoantibody detection". The results showed: SOX2 positive; GBU4-5 positive. The joint diagnosis by the two parties was highly suspicious of lung tumors, and the patient quickly chose surgery. The pathological examination results after surgical resection showed: micro-invasive lung cancer (dorsal segment of right lower lung).

What is lung cancer autoantibody testing?

"Lung cancer autoantibody detection" is an emerging ultra-early lung tumor screening project introduced by the Department of Nuclear Medicine in recent years. It only requires drawing a tube of blood and can be combined with CT to effectively conduct the initial diagnosis of lung cancer. Under the influence of various carcinogens in the human body, our immune system recognizes these tumor cells, responds, and produces corresponding antibodies against the specific antigens on these tumor cells. These antibodies are called "autoantibodies."

Figure 5 Serum tumor markers

Due to the high specificity and sensitivity of the antigen-antibody reaction, even if there is interference from a large amount of albumin and other proteins in the serum, it can Accurately detected at very low concentrations.

This test selects seven highly specific lung cancer-related targets. Each target is independent and non-crossing, namely: GAGE7, CAGE, MAGE-A1, SOX2, GBH4-5, PGP9.5, P53. These seven targets can be divided into five groups according to different signaling pathways, namely P53 tumor suppressor gene, CTA, transcription factors, helicases, and deubiquitinating enzymes. The representative signaling pathways are: acquisition of cell immortality, abnormal proliferation signals, abnormal transcription signals, genome instability, and abnormal proteolysis. Any positive indicator indicates that the tumor cells have strong biological activity, rapid proliferation, and easy invasion and metastasis.

Six multi-center studies have shown that lung cancer serum antibodies combined with chest CT can assist in the early diagnosis of lung cancer, with a positive accuracy rate of 95%. Studies have shown that "lung cancer autoantibody detection" can detect the occurrence of lung cancer 3-5 years earlier than CT.

How do the general population choose among pulmonary nodule screening examinations?

Among low- and medium-risk groups, LDCT (low-dose spiral CT) is not a routine recommended screening method. Non-invasive and radiation-free lung cancer autoantibody detection can be used as a baseline screening method (that is, first use the lung cancer itself Antibody test screening, and those who are positive will undergo LDCT screening). Avoid missed diagnosis of non-high-risk groups and improve the early diagnosis rate of lung cancer.

For high-risk groups, the national CT screening guidelines recommend LDCT (low-dose spiral CT) as a routine screening method. However, the false positive rate of CT is high. Lung cancer autoantibody detection can be used as a supplementary detection method to reduce the false positive rate. It can also reduce small cell lung cancer and other early-stage lung cancer that are easily missed by CT. To sum up, the most correct attitude towards pulmonary nodules is: "Don't ignore it, don't be nervous".

Figure 6 Lung cancer screening flow chart

From: Department of Thoracic Surgery, Shuguang Hospital Affiliated to Shanghai University of Traditional Chinese Medicine