BRONCHIAL ARTERIAL PATTERNS IN PULMONARY METASTASIS

The epidemiology and biology of pulmonary metastases

Our goal in this chapter is to explore the complex processes of metastasis and why there is a predisposition for this to occur in the lung. In addition, we aim to describe the incidence of pulmonary metastases in various contexts and based on the origin of the primary tumor. There are unique characteristics of the pulmonary system that make metastases more likely to occur in the lung than anywhere else in the body. Some of these characteristics include receiving the entire cardiac output every minute, having the densest capillary bed in the body, and being the first reservoir of most lymphatic drainage entering the venous system. There are multiple postulated routes of metastasis to the pulmonary system including hematogenous and lymphatic routes with early or late dissemination. The vascularization of pulmonary metastases is variable and complex, often recruiting supply from bronchial and pulmonary origin. There are also many biochemical factors in the tumor microenvironment that play a key role in the development of lung metastases including vascular endothelial growth factor (VEGF), interleukin-8 (IL-8), very late antigen 4 (VLA-4) and intercellular adhesion molecule 1 (ICAM-1). Studies vary widely in reported rates of pulmonary metastases due to differences in clinical study design, however, it is commonly accepted that up to half of autopsies performed on patients who died of malignancy have pulmonary metastases. In a surgical series describing the incidence of primary cancer types with resected pulmonary metastases the most common sites were thyroid, colon, breast, genitourinary tract, skin, liver, breast, and adrenal glands.

Microflow imaging of contrast-enhanced ultrasound for evaluation of neovascularization in peripheral lung cancer

The aim of this study was to investigate the role of microflow imaging (MFI) of contrast-enhanced ultrasound (CEUS) for evaluating microvascular architecture of different types of peripheral lung cancer (PLC) and to explore the correlated pathological basis.Ninety-five patients with PLC were enrolled in this study. Two radiologists independently evaluated the microvascular architecture of PLC with MFI. The interobserver agreement was measured with Kappa test. The diagnosis value of MFI was calculated. With pathological analysis, the correlation between MFI and microvascular density (MVD)/microvascular diameter (MD) was evaluated.Of the 95 PLCs, MFI were mainly classified "dead wood" (27.4%, 25.3%), "vascular" (47.4%, 49.5%), and "cotton" (20.0%, 20.0%) patterns by the 2 readers. Kappa test showed a good agreement between the 2 readers (Kappa = 0.758). The "dead wood" can be regarded as a specific diagnostic factor for squamous carcinoma; the sensitivity, specificity, and accuracy was 62.9%, 93.3%, and 82.1%, respectively. The "vascular" and "cotton" patterns correlated well with adenocarcinoma and SCLC (small cell lung cancer); diagnostic sensitivity, specificity, and accuracy were 86.7%, 65.7%, and 78.9%, respectively. MVD of "dead wood" was lower than "vascular" and "cotton," while MD was bigger than the other 2 patterns (P < 0.05). There was a good correlation between MFI and histopathological types of PLC as well as between MFI and MVD/MD (P < 0.05).MFI has the advantage to display the microvascular architecture of PLCs and might become a promising diagnostic method of histopathological types of PLC. MFI features also correlated well with its pathological basis, including MVD and MD.

Y90-radioembolization of lung metastases via the bronchial artery: a report of 2 cases

We report successful Y90-radioembolization of the lung applying Y90-resin microspheres via the bronchial artery in two patients with diffuse colorectal and renal cancer metastases, respectively. The deposition of radioactive Y90-resin-microspheres was technically feasible and resulted in a reasonable absorbed dose in the tumors. However, open questions remain regarding dosimetry and safe dose exposure to the lung. The technique warrants thorough investigation before clinical use. A Phase I trial to evaluate safety and preliminary efficacy is under preparation.

JTE-522, a selective COX-2 inhibitor, interferes with the growth of lung metastases from colorectal cancer in rats due to inhibition of neovascularization: A vascular cast model study

The lung is a frequent site of metastasis from colorectal cancer, but angiogenesis of lung metastases has not been clarified. Some COX-2 inhibitors prevent tumor growth, although the inhibitory mechanism at the metastatic site is obscure. We investigated the microvascular structure of small lung metastases and the effect of JTE-522, a selective COX-2 inhibitor, on the angiogenesis of pulmonary metastases from colorectal cancer in rats. The tail veins of 25 male F344/DuCrj rats, aged 5 weeks, were injected with a tumor suspension containing 5 x 10(6) RCN-9, a rat colon cancer cell line. Three weeks later, pulmonary vascular resin corrosion casts were taken and the vascularity of metastases was studied using stereo and scanning electron microscopes. We investigated the effect of 0, 10 and 30 mg/kg/day of JTE-522 on the angiogenesis of pulmonary metastases in 3 groups of 5 male rats out of 25. JTE-522 reduced the diameter of tumor vessels as well as the number and size of metastatic tumors. The diameter of tumor vessels and the size of lung metastases significantly and positively correlated with neovascularization in the control group, but not in the JTE-522-treated groups. JTE-522 also affected type of vasculature of metastases, which differed depending on their size. JTE-522 interfered with the growth of hematogenous metastatic tumors by disrupting neovascularization. However, JTE-522 may have some important mechanisms other than inhibition of neovascularization. JTE-522 may be one of the therapeutic agents for the treatment of hematogenous metastasis of colorectal cancer.