Multiplication time is an important method of clinical value.By comparing twiceimageDuring inspectiontubercleVolume changetumourGrowth rate.The doubling time is the time required to double the nodule volume.In the past, chest X-ray film and CT were used to directly measure the diameter of pulmonary nodules, and the data were taken into the volume calculation formula V=л/6 × ab2, and the doubling time VDT=t × log2/log (Vt/V0), so as to obtain the doubling time of the nodules and tumors.The tumor volume calculated based on the measurement of the diameter and line of the chest X-ray nodules is less accurate than the measurement of the diameter and line of CT (especially HRCT).
Multiplication time is an important method of clinical value.The tumor growth rate was calculated by comparing the changes of nodule volume during two imaging examinations.The doubling time is the time required to double the nodule volume.In the past, chest X-ray film and CT were used to directly measure the diameter of pulmonary nodules, and the data were taken into the volume calculation formula V=л/6 × ab2, and the doubling time VDT=t × log2/log (Vt/V0), so as to obtain the doubling time of the nodules and tumors.The tumor volume calculated based on the measurement of the diameter and line of the chest X-ray nodules is less accurate than the measurement of the diameter and line of CT (especially HRCT).
A method for measuring tumor doubling time
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MDCT is commonly used for volume measurement or similar technology, which can measure the volume of nodules directly and accurately, and is conducive to accurate measurement of doubling time.However, when there are many blood vessels or satellite lesions near the hilum, pleura and periphery of the nodule, the MDCT volume direct measurement method has a certain deviation. At this time, the CT diameter measurement method is better.In general, MDCT volume measurement is more precise and accurateSolitary pulmonary noduleIt is the best measurement method, especially suitable for tracking observation of small pulmonary nodules, which is conducive to the qualitative determination of nodules and the determination of curative effect.
Distribution of tumor doubling time
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In the past, the doubling time of nodules was measured based on chest X-ray films. It was generally believed that the doubling time of tumors was 30~400 days. Less than 30 days often indicated acute inflammation, while more than 400 days usually indicated acute inflammationBenign tumorOr granulomatous lesions.Lung tumors with a doubling time of more than 150 days were classified as chronic growth tumors, while those with a doubling time of less than 150 days were classified as fast-growing tumors.The tumor doubling time was 223d for adenocarcinoma, 104 days for squamous cell carcinoma, and 80 days for small cell lung cancer,Large cell lung cancer79d；212 days for stage I lung cancer, 119 days for stage II lung cancer, 126 days for stage III lung cancer, and 149 days for stage IV lung cancer.However, the distribution of tumor doubling time of pulmonary nodules measured by CT is quite different from that measured by chest X-ray, which changes the traditional view in the past, especially for small adenocarcinoma of the lung, which is first found by CT but not easily displayed by chest X-ray, its tumor doubling time is longer.Hesegawa et al studied lung cancer screened by low-dose CT, and found that the tumor doubling time was different for nodules with different densities on CT: 813 days for ground glass density nodules, 457 days for mixed density nodules, and 149 days for solid nodules;The tumor doubling time of smokers was 292 days, while that of non-smokers was 607 days, indicating that smoking can accelerate the rapid growth of tumors;536 days for nodules with diameter less than 10 mm, 466 days for nodules with diameter between 10 mm and 15 mm, 325 days for nodules with diameter between 16 mm and 20 mm, and 299 days for nodules with diameter greater than 20 mm, suggesting that the larger the tumor, the faster the tumor growth;The chest X-ray film can show the tumor for 250 days, and can not show the tumor for 536 days;533 days for adenocarcinoma and 129 days for squamous cell carcinoma,small cell lung cancer97d.
Pathological basis affecting tumor doubling time
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The doubling time of lung tumor is directly related to its pathological growth characteristics, histological type and differentiation degree.Generally speaking, the doubling time of lung adenocarcinoma is longer than that of squamous cell carcinoma, small cell lung cancer and other tissue types;The well differentiated lung cancer doubled longer than poorly differentiated or undifferentiated lung cancer;The time of tumor multiplication in Hilic growth is shorter than that in Lepidic growth.In recent years, low-dose CT screening for early lung cancer or clinical CT examination occasionally found that the focus was mostly small nodules, especially peripheral small lung adenocarcinoma (≤ 20mm), which often showed ground glass density (GGO) nodules, which could be combined with consolidation or solid components. Pathologically, tumor cells in the GGO generation grew along the alveolar wall, accompanied by residual air containing alveolar tissue.
Adenocarcinoma also replaced squamous cell carcinoma as the most commonPeripheral lung cancer。Noguchi et al. observed the histopathology of 236 cases of peripheral small adenocarcinoma with diameter ≤ 20mm, and found 6 subtypes based on the growth characteristics of the tumor:
Type A: localized alveolar carcinoma, about 7.2%;
Type B: localized alveolar carcinoma with alveolar collapse, about 7.2%;
Type C: localized alveolar carcinoma with fibroblastic hyperplasia, about 59.7%;
Type D: poorly differentiated adenocarcinoma, about 18.6%;
Type E: tubular adenocarcinoma, about 3.8%;
Type F: papillary adenocarcinoma with compression and destructive growth, about 3%.
Small adenocarcinoma of lung type A and B withoutLymph node metastasisThe 5-year survival rate was 100%, which was considered as early carcinoma in situ;Type C is the further development of type A and B, which is an early invasive cancer;D. Type E and F small adenocarcinoma of the lung are small progressive tumors with poor clinical prognosis.A. Type B and C tumors belong to the type of ambush wall growth tumor, while type D, E and F tumors belong to the type of solid growth tumor[1]。
CT findings of lung cancer are closely related to its pathological growth characteristics.Yang et al. conducted a comparative study on HRCT and histopathology of 59 peripheral small lung adenocarcinoma displayed by low-dose CT, and found that there were four types: type I was a pure GGO nodule, accounting for 31%, with a size of (10.7 ± 3.7) mm and a CT value of (- 590 ± 90) Hu. Pathological findings showed that tumor cells grew along the alveolar wall, without alveolar collapse.Type II is a low-density heterogeneous nodule, accounting for 25%, with a size of (11.3 ± 3.3) mm and a CT value of (- 360 ± 90) Hu. Pathological manifestations are that tumor cells grow along the alveolar wall, accompanied by scattered alveolar collapse.Type III is central high-density with peripheral GGO nodules, accounting for 17%, with a size of (15.2 ± 3.6) mm, a CT value of (- 440 ± 130) Hu, a central area of - 150 Hu, and a peripheral area of - 610 Hu.Pathological manifestation: tumor centerElastic fibreHyperplasia, accompanied by alveoli collapse, tumor cells in the surrounding area grew in a wall hugging manner, without alveoli collapse.Type IV is a homogeneous soft tissue density nodule, accounting for 27%, with a size of (14.5 ± 2.7) mm and a CT value of (10 ± 30) Hu. Pathological manifestations are solid growth of the tumor without air containing alveolar tissue.The HRCT classification of Yang et al. has good consistency with the pathological subtype of small lung adenocarcinoma of Noguchi et al., 94% of type A tumors show type I nodules, 71% of type B tumors show type II nodules, 29% of type C tumors show type III nodules, 50% of type C tumors show type IV nodules, and 100% of type D, E, and F tumors show type IV nodules.
The CT features of lung cancer can predict its clinical prognosis to a certain extent.Yang et al. also evaluated the tumor doubling time of adenocarcinoma, and found that type A and B tumors contain GGO components, and the tumor doubling time is more than one year, and the tumor grows slowly;Type D, E and F are solid components, and the tumor doubling time is mostly less than one year. The tumor grows slowly.Kim et al. reported 227 cases of bronchoalveolar carcinoma and adenocarcinoma. The higher the content of GGO, the better the prognosis of patients. The results showed that the proportion of GGO was higher than that of noneLymph node metastasis, distant metastasis and no tumor recurrence were positively correlated (P values were 0.017, 0.007 and 0.020, respectively).Aoki et al. reported that the proportion of GGO in 17 cases of small adenocarcinoma was more than 50%, without lymph node metastasis and postoperative recurrence.In conclusion, the higher the proportion of GGO components in nodules of peripheral small adenocarcinoma on HRCT, the more tumor cells grow along the alveolar wall in pathology (mainly in type A and B), the longer the tumor doubling time, the lower the lymph node metastasis rate, and the better the clinical prognosis.On the contrary, the lower the proportion of GGO in the nodule, the more solid the pathology is (seen in type D, E and F). The shorter the tumor doubling time is, the higher the lymph node metastasis rate is, and the clinical prognosis is relatively poor[2]。
The value of tumor doubling time in the diagnosis of lung cancer
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CT screening for lung cancer or clinical CT examination often finds small pulmonary nodules, whose pathology is tumor, inflammatory granuloma or tuberculoma. Accurate characterization is a challenge for chest imaging diagnostic physicians.Generally speaking, the small nodules found by CT scanning should be first scanned by HRCT, and then image post-processing, including 3D reconstruction.Based on the size, shape, edge, internal structure (GGO, calcification, fat, vacuole sign and bronchial weather syndrome), CT value and peripheral lung tissue of the nodules, a comprehensive analysis can be made for most nodulesQualitative diagnosisHowever, sometimes the initial HRCT diagnosis of small lung cancer is difficult, and follow-up observation is needed.Imaging tracking involves the selection of observation interval.This problem is more important. On the one hand, it is necessary to reduce the economic burden of patients and the X ray radiation dose. On the other hand, it is necessary to diagnose small lung cancer as soon as possible and remove it in time to improve the 5-year survival rate of patients.It is a scientific method to determine the follow-up review time based on the tumor multiplication time. Pure GGO nodules should be reviewed by CT in April to June, while those with GGO combined with solid components should be reviewed by CT in February to March, and pure solid nodules should be reviewed by CT in January to February.In addition, because smoking also affects the tumor doubling time of the nodules, it is advisable to recheck CT for smokers' pulmonary nodules in 1 to 2 months, while non-smokers should recheck CT in 3 to 4 months.In CT tracking, if the nodule increases or the size of the nodule does not change but the density increases, it should be highly suspected of being lung cancer, and surgical resection is recommended.
In conclusion, with the development and progress of imaging technology, the measurement of tumor doubling time has become more precise and accurate, changing the past understanding of tumor doubling time distribution of lung cancer.Early small adenocarcinoma of the lung showed pure GGO nodules or partial GGO nodules on HRCT. The tumor doubling time was longer, often more than 400 days, and the clinical prognosis was good.Understanding the new characteristics of tumor doubling time will be helpful for CT trackingQualitative diagnosisAnd differential diagnosis.
