What is a pulmonary nodule? In fact, nodules are only a descriptive word in imaging, not the nature of lesions, that is to say, they are not medical diagnosis! In imaging, circular lesions with density increase less than 3cm in diameter found by chest CT are usually described as nodular lesions, those with diameter less than 1cm are called "small nodules" and those with diameter less than 0.5cm are called "small nodules".
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 we are most concerned about, and what doctors should do, is how to distinguish whether nodules are benign or malignant, and then give corresponding suggestions for diagnosis and treatment.
Figure 1 pulmonary nodules
"looks" are different
Pulmonary nodules can be divided into three types.
Although they are all called pulmonary nodules, according to the "appearance", pulmonary nodules can generally be divided into three types: pure ground glass nodules, partial solid ground glass nodules and pure solid nodules.
First, ground glass nodule (GGN) or ground glass shadow (GGO).
The so-called ground glass, like the ground glass we see in our lives, is covered with a layer, but we can still see the lung tissue behind the glass.
Figure 2 Pure wool glass node
The second type of nodule is solid nodule (SPN).
From the CT image, the nodule is dense and completely opaque, and no black lung tissue can be seen, which is a solid nodule.
Fig. 3 Solid nodules
Thirdly, mixed glass nodule (mGGN).
This kind of nodule is located in the "middle" of the first two. On CT images, it is a mixture of ground glass and solid nodules, and there are solid components in the shadow of ground glass.
Fig. 4 Mixed ground glass nodules
Three kinds of nodules may be benign or malignant. Benign includes spherical pneumonia, tuberculoma, hamartoma and fibroplasia. Malignant nodules often have some special manifestations, such as burr sign, lobulation sign, pleural traction sign, microvascular sign, spinous process sign and so on.
There is a golden rule to treat diseases, that is, "early detection, early diagnosis and early treatment", especially cancer! Then how can the diagnosis be more accurate? This is also a matter of concern to everyone.
Case: "Good" and "evil" are inseparable, so "lung cancer autoantibody test" should be done.
5 1 year-old Li, male, found pulmonary nodules in physical examination in 2020. Chest CT: Ground glass nodule of the right lower lung, about 7mm in size, with low density shadow. After visiting our hospital, the results of the first CT report and the follow-up results after 3 months can't distinguish whether the nodule is benign or malignant.
It is difficult to evaluate the nature of nodules by CT alone, and patients themselves are very anxious. Therefore, it is suggested that they draw blood for "lung cancer autoantibody test". The results showed that SOX2 was positive; GBU4-5 was positive. Both sides jointly diagnosed a highly suspected lung tumor, and the patient quickly chose surgery. After surgical resection, pathological examination showed that: (right lower lung posterior segment) pulmonary micro-invasive lung cancer.
What is lung cancer autoantibody detection?
"Detection of lung cancer autoantibodies" is a new project of ultra-early lung tumor screening launched by nuclear medicine department in recent years. Only one tube of blood needs to be drawn, and combined with CT, the initial diagnosis of lung cancer can be effectively carried out. Under the influence of various carcinogenic factors, our immune system recognizes these tumor cells and reacts to produce corresponding antibodies against specific antigens on these tumor cells. These antibodies are called "autoantibodies".
Fig. 5 Serum tumor markers
Because the antigen-antibody reaction has high specificity and sensitivity, it can be accurately detected at a very low concentration even if there is a large amount of protein interference in serum.
Seven highly specific lung cancer-related targets were selected, each of which was independent and non-intersecting, namely: GAGE7, CAGE, MAGE-A 1, SOX2, GBH4-5, PGP9.5 and P53. These seven targets can be divided into five groups according to different signal pathways, namely P53 tumor suppressor gene, CTA, transcription factor, helicase and ubiquitination enzyme. Representative signal pathways include cell immortalization, abnormal proliferation signal, abnormal transcription signal, genomic instability and abnormal protein hydrolysis. Any positive index means that tumor cells have strong biological activity, rapid proliferation and easy invasion and metastasis.
Six multi-center studies show that the positive accuracy of lung cancer serum antibody combined with chest CT in early diagnosis of lung cancer is 95%. Studies have shown that "lung cancer autoantibody detection" found lung cancer 3-5 years earlier than CT.
How do the general population choose in the screening of pulmonary nodules?
Low-dose spiral CT (LDCT) is not a routine recommended screening method for low-risk population. Non-invasive and non-radiation detection of lung cancer autoantibodies can be used as a baseline screening method (that is, lung cancer autoantibodies are screened first, and then LDCT is used to screen positive people). 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. The false positive rate of CT is high, so the detection of lung cancer autoantibodies can be used as an auxiliary detection method to reduce the false positive rate, and at the same time, it can also reduce the early lung cancer that is easily missed by CT. To sum up, our most correct attitude towards pulmonary nodules is: "Don't ignore it, don't be nervous".
Fig. 6 Flow chart of lung cancer screening
Since: Department of Thoracic Surgery, Shuguang Hospital affiliated to Shanghai University of Traditional Chinese Medicine.