Method for treating locally advanced pelvic tumors

Abstract

FIELD: surgery; oncology; interventional radiology.SUBSTANCE: used to treat locally advanced pelvic tumors. Computed tomography with intravenous contrast enhancement is performed, an individual topographic model of the pelvic vessels is created, compared with the topographic model of the obligate pelvic vessels, and collateral arterial branches are identified. The coefficient of variability is calculated as the ratio of the number of collateral branches to the total number of segments in the internal iliac artery system. If the coefficient of variability is higher than 0.15, a high risk of incomplete embolization with preservation of collateral blood flow is predicted and the scope of endovascular intervention is expanded with additional chemoembolization of the identified arterial branches before performing organ-preserving surgery.EFFECT: method improves treatment effectiveness and reduces the risk of postoperative complications by specifically blocking additional sources of blood supply to the tumor and creating a high local concentration of the chemotherapy drug in the area of the pathological lesion.1 cl, 1 ex

Description

[0001] The invention relates to medicine, in particular to surgery, oncology, interventional radiology, and can be used to treat locally advanced pelvic tumors.

[0002] A known method for treating locally advanced pelvic tumors involves surgical intervention that includes pelvic exenteration. The technique involves radical removal of the tumor conglomerate as a single block with surrounding tissues. [Kostyuk I. P., Vasiliev L. A., Kostin A. A., Kaprin A. D. Multivisceral resections in the complex treatment of pelvic tumors / / Bulletin of the National Medical and Surgical Center named after N. I. Pirogov. 2016. No. 1 – pp. 108–116].

[0003] Another method for treating locally advanced pelvic tumors is also known, using external beam or contact radiation therapy. This technique is based on irradiating the tumor with ionizing radiation in order to achieve local disease control. [Startseva Zh. A., Lushnikova P. A., Sukhikh E. S. External beam radiation therapy as an alternative to brachytherapy for locally advanced cervical cancer / / Siberian Journal of Oncology. 2025, No. 2. – P. 162–168].

[0004] A disadvantage of surgical treatment is the inability to perform organ-preserving surgery in most patients with locally advanced pelvic tumors. A fundamental limitation of radiation therapy for locally advanced pelvic tumors is the development of massive tumor disintegration during irradiation, leading to the formation of multiple pelvic fistulas and severe intoxication syndrome.

[0005] The closest method to the claimed one is the treatment of locally advanced pelvic tumors using selective embolization of the main arteries. It involves performing selective angiography followed by the introduction of embolizing particles into the arterial vessels for devascularization of the tumor conglomerate [Babaeva N. A., Antonova I. B., Aleshikova O. I., Ivashina S. V., Shakhbazyan K. R., Bolshakova S. A., Ovodenko D. L., Ashrafyan L. A. Selective embolization and chemoembolization of the uterine arteries as a stage of treatment of patients with locally advanced cervical cancer (clinical examples) / / Bulletin of the Russian Scientific Center of Roentgenology and Radiology. 2017. No. 3 – p. 8].

[0006] The main drawback of the prototype method is its ability to stop bleeding without reducing tumor volume or assessing the necrotic component. The technique does not provide a preliminary quantitative assessment of the degree of tumor tissue necrosis and does not take into account collateral arterial blood flow. The lack of control over the volume of necrotic tumor tissue during embolization increases the risk of surgical complications in the postoperative period due to the massive release of tissue breakdown products in patients.

[0007] This method does not establish threshold values ​​for determining the advisability of endovascular intervention. This technique is used to achieve a local cytotoxic effect; however, it does not provide a preliminary quantitative assessment of the tumor's necrotic component, which precludes predicting the advisability of hyperthermic perfusion or the risk of developing a systemic inflammatory response.

[0008] Failure to take into account the presence of third-order branches creates unfavorable conditions for preserving viable residual tissue during reconstructive and organ-preserving surgeries to improve the quality of life of patients with locally advanced pelvic tumors.

[0009] A disadvantage of the method is also the lack of the ability to plan the scope of the intervention taking into account the characteristics of the tumor and the distribution of patients into risk groups for an unfavorable course of the postoperative period.

[0010] The objective of the present invention is to improve the effectiveness of treatment and reduce the risk of postoperative complications.

[0011] The technical result of the stated problem is achieved by the fact that in the method for treating locally advanced pelvic tumors, including chemoembolization of the internal iliac arteries, computed tomography with intravenous contrast enhancement is performed, an individual topographic model of the pelvic vessels is created, compared with the topographic model of the obligate pelvic vessels and collateral arterial branches are identified, the coefficient of variability is calculated as the ratio of the number of collateral branches to the total number of segments in the internal iliac artery basin, with a variability coefficient value above 0.15, a high risk of incomplete embolization with preservation of collateral blood flow is predicted and the scope of endovascular intervention is expanded by additional chemoembolization of the identified arterial branches before performing organ-preserving surgery.

[0012] Calculation of the branching variability coefficient as the ratio of the number of additional arterial branches to the total number of visualized segments is based on the established pattern according to which the presence of multiple additional arterial blood supply pathways creates conditions for maintaining tissue viability after chemoembolization of the main blood supply trunks.

[0013] Using a quantitative coefficient instead of subjective visual assessment allows for an objective assessment of the potential expansion of the intervention and a standardized treatment approach for patients with different vessel branching patterns. The choice of a coefficient threshold value above 0.15 is justified by the fact that exceeding this threshold corresponds to the presence of additional collaterals amounting to more than 15% of the total number of segments, which is clinically significant for maintaining tumor blood supply and does not result in sufficient reduction of the tumor conglomerate volume.

[0014] The method is as follows. During preoperative preparation of patients with locally advanced pelvic tumors, computed tomography with intravenous contrast is performed. Scanning is performed in the arterial phase 25-30 seconds after the administration of an iodine-containing preparation at a dose of 1.5 ml per 1 kg of body weight. The thickness of the reconstructed slices should not exceed 1 mm to ensure sufficient detail of small-caliber vascular structures. The obtained data in DICOM format is imported into 3D Slicer version 5.8.1 with the preinstalled VMTK, Extra Markups, and Segment Editor extensions. Semi-automated segmentation of the arterial bed from the aortic bifurcation to the femoral arteries is performed. In the first step, the density range of contrasted arteries is determined by point estimation in Hounsfield units (HU), after which threshold segmentation from 70 to 300 units is applied to create a working zone.Using the Paint tool, vessels are manually drawn, including the internal iliac arteries and their branches, according to the classification of locally advanced pelvic tumors. Using the VMTK module, a topological graph model (Network Model) is extracted, representing the vascular tree as branching nodes and connecting edges, ignoring spatial coordinates. The resulting structure is exported in VTK or STL format for subsequent analysis. Using developed Python scripts in 3D Slicer, automated alignment of individual models is performed, producing a model reflecting the obligate arterial branches present in all patients, regardless of individual anatomical features.

[0015] When examining a specific patient, the individual vascular topography is compared with the topography of the obligate pelvic vessels, and collateral arterial branches are then identified. The coefficient of variation is calculated as the ratio of the number of collateral branches to the total number of segments in the internal iliac artery system. A coefficient value greater than 0.15 predicts a high risk of incomplete tumor embolization, and the extent of endovascular intervention is expanded to ensure complete coverage of the tumor site and to reduce the tumor volume before performing organ-preserving surgery.

[0016] Example. Patient M., 59 years old. Admitted to the Mariinsky Hospital in St. Petersburg on October 20, 2022. She was diagnosed with locally advanced cervical cancer with bladder wall invasion (stage IVA, T4N1M0), complicated by the formation of a vesicovaginal fistula and recurrent bleeding. A decision was made to perform chemoembolization of the internal iliac arteries using the proposed method. The count revealed 8 additional branches, with a total of 42 identified. The calculated coefficient of variation was 0.19, which exceeded the threshold of 0.15. Based on this threshold, a high risk of incomplete embolization was predicted. During the procedure, bilateral chemoembolization of the main trunks was performed with additional catheterization and chemoembolization of the 8 identified additional branches. The use of this method made it possible to reduce the size of the tumor process, perform organ-preserving surgery on the bladder, and avoid performing anterior pelvic exenteration.

[0017] The claimed method is an effective and reproducible treatment for locally advanced pelvic tumors. It enables quantitative prediction of the risk of incomplete devascularization and personalization of the extent of endovascular intervention, taking into account individual topological variability of the arterial bed. The method is accessible to oncologic surgeons, endovascular surgeons, and interventional radiologists and requires no additional equipment other than standard computed tomography. The use of a quantitative coefficient eliminates the subjectivity of visual assessment and ensures high reproducibility between operators. Implementation of this method increases the effectiveness of endovascular treatment by reducing tumor burden in the pelvis.

Claims

A method for treating locally advanced pelvic tumors, including chemoembolization of the internal iliac arteries, characterized in that computed tomography with intravenous contrast enhancement is performed, an individual topographic model of the pelvic vessels is created, compared with a topographic model of the obligate pelvic vessels and collateral arterial branches are identified, the coefficient of variability is calculated as the ratio of the number of collateral branches to the total number of segments in the internal iliac artery basin, with a value of the coefficient of variability above 0.15 a high risk of incomplete embolization with preservation of collateral blood flow is predicted and the scope of endovascular intervention is expanded with additional chemoembolization of the identified arterial branches before performing organ-preserving surgery.