Computerized System for Staging Peritoneal Surface Malignancies
Peritoneal surface malignancies (PSMs) are usually staged using Sugarbaker’s Peritoneal Cancer Index (PCI) and completeness of cytoreduction score (CC-s). Although these staging tools are essential for selecting patients and evaluating outcome after cytoreductive surgery (CRS) plus hyperthermic intraperitoneal chemotherapy (HIPEC), both scoring models lack some anatomic information, thus making staging laborious and unreliable. Maintaining Sugarbaker’s original concepts, we therefore developed a computerized digital tool, including a new anatomic scheme for calculating PCI and CC-s corresponding closely to patients’ real anatomy. Our new anatomic model belongs in a web-based application known as the PSM Staging System, which contains essential clinical and pathological data for the various PSMs currently treated.
The new digital tool for staging PSM runs on a personal computer or tablet and comprises male and female colored anatomic models for the 13 endoabdominal regions, with borders defined according to real anatomic landmarks. A drag-and-drop tool allows users to compute the PCI and CC-s, making it easier to localize and quantify disease at diagnosis and throughout treatment, and residual disease after CRS.
Once tested online by registered users, our computerized application should provide a modern, shareable, comprehensive, user-friendly PSM staging system. Its anatomic features, along with the drag-and-drop tool, promise to make it easier to compare preoperative and postoperative PCIs, thus improving the criteria for selecting patients to undergo CRS plus HIPEC. By specifying the size, site, and number of residual lesions after CRS plus HIPEC, our digital tool should help stratify patients into outcome classes.
KeywordsMinimal Residual Disease Peritoneal Cancer Index Anatomic Model Digital Tool Hyperthermic Intraperitoneal Chemotherapy
The currently available PCI and CC-s classifications, according to Sugarbaker, leave room for improvement. The poorly informative two-dimensional anatomic model for scoring the PCI fails to reflect the patient’s real anatomy, as seen by the radiologist or surgeon. Although Sugarbaker himself later listed the anatomic structures involved in the 13 abdominopelvic regions,16 the model lacked depth, the anatomic structures contained in a specific abdominal region overlapped, and imaginary lines subdivided the regions. Hence, the problem remained unsolved. The PCI applied in this way therefore tends to make assessment more laborious and probably yields less reliable diagnostic and surgical findings on the extent of disease. Similar limitations apply to the CC-s because it completely lacks an anatomic model and therefore gives no information on the sites of residual disease or their number.
Despite keeping Sugarbaker’s original concepts, the foregoing shortcomings prompted us to facilitate PSM staging by optimizing the same anatomical model for applying the PCI and CC-s. With this concept in mind, we aimed to develop a computerized scheme containing images with a three-dimensional effect suitable for use during diagnosis or therapy and corresponding as closely as possible to the patient’s real anatomy. We included this model in a new web application known as the PSM Staging System, which contains the main clinical and pathological data for the various PSMs currently treated (www.psmss.net). The digital technology used in the new anatomic model should help localize and quantify, with greater precision, the extent of peritoneal disease (PCI) in diagnostic and surgical settings, specifying the size and number of lesions. Using the same anatomic model, the same digital tool also specifies the size and number of residual lesions after CRS, as well as the site of residual disease. Both user-friendly features aim to make the PCI and CC-s easier to mark and more reliable, therefore facilitating information exchange among physicians involved in treating PSMs. By providing a single web application for radiologists and surgeons, we also wanted to make it easier to compare preoperative and surgical disease staging, thereby improving patient selection criteria. With a more realistic anatomic model, we finally sought to extend current prognostic information correlating the PCI and CC-s according to the specific anatomic sites.
Computerized Peritoneal Surface Malignancy Staging System
Web Application Technical Specifications
The PSM staging system is a web-based application accessible through a network that uses a standard web browser as the user terminal and therefore runs on traditional network protocols. To ensure fully secure data management, a data encryption protocol allows safe communication from the source to the recipient (end-to-end) in transfer control protocol/internet protocol (TCP/IP) networks supplying authentication, data integrity, and full data transport-level encryption. The PSM staging system is written in a cross-platform language (HTML5), with the user’s interface code specified in remote. This solution substantially affects functioning; the major advantage is that the web application has no influence whatsoever on the device’s memory capacity or on its ability to calculate data, given that the core processor and user’s interface are on a remote server. Through their supplied password, authenticated users, once connected to the system, will be able to input data for new patients or update their pre-existing data. Using a simple drag-and-drop system, the user will be able to indicate the extent, site, and number of malignant implants present at diagnosis and therapy, or eventually as residual lesions after surgery, positioning them within the anatomic model, and the system will record all the data inserted on cloud. All data inserted can be visualized and compared, and also exported as a PDF document in a completely anonymous manner. No recorded information will in any way be traceable back to the patient. The system will be optimized for use on a tablet (including iPad, Galaxy Tab, Xperia, and Nexus 9) or computer [personal computer (PC), Apple], and updated to run on all the latest-generation web browsers.
Our computerized, web application for staging PSM fulfills an unmet need for a modern, shareable, comprehensive, user-friendly staging system for a life-threatening, although in selected cases nowadays, treatable disease. Our web-based system has another advantage; it collects the main information for each patient, including clinical features (performance status, histology, disease settings), extent of disease at diagnosis and at surgery (PCI), and residual disease after surgery (CC-s), and distinguishes these features according to the various PSM origins.
The colored images with a three-dimensional effect in our anatomic model also help to describe more accurately the spatial extent of PSM. Having the most precise information possible on the extent and sites involved by malignant spread is an essential requisite for planning therapy and assessing outcome.
Despite keeping Sugarbaker’s original concepts, subdividing the various abdominal regions according to real rather than imaginary boundaries, and describing them in detail, as well as including the user-friendly drag-and-drop feature, makes computing the PCI an easier task and should provide more reliable findings. The new subdivision, distinguishing the abdominal wall apart from the other regions, received strong support from publications, indicating abdominal wall disease as being responsible for high postoperative morbidity, and identifying it as an independent prognostic variable.17,18 Visualizing the various abdominal regions in detail allows the physician to far more precisely localize malignant disease in each anatomic site, thus defining the relationship between the organs and structures involved and outcome, a problem so far addressed only for the small bowel.10 In general, these advantages could also help to overcome the reported drawbacks in Sugarbaker’s original PCI.16,19,20 These new features, as well as the drag-and-drop tool, should make it easier to compare the PCI computed in the preoperative setting from diagnostic imaging or at laparoscopy with the PCI computed by the surgeon at surgical exploration, thus improving the patient selection criteria. Although the main, currently used imaging techniques [computed tomography (CT), magnetic resonance imaging (MRI), and positron emission tomography (PET)/CT] achieve high reliability indexes when undertaken by radiologists experienced in this field, intraoperative assessment tends to disclose malignant implants that diagnostic imaging before CRS has missed or underestimated, especially in specific abdominal regions.21,22 The problem on how to select patients with PSM to undergo surgery acquires especial importance in patients with PSM from colorectal and gastric cancer, given the reportedly high incidence of open–close procedures.14,23
A distinctive innovation in our PSM staging system is that for LS1 and LS2 we explicitly specify the number of lesions found in a given abdominal region. Although these data leave the PCI classification unchanged, knowing the number of lesions present in each region could provide important, previously unavailable information that could help guide therapy and indicate the patient’s outcome.
By using the same anatomic model and specifying the size, site, and number of residual lesions after CRS, our digital tool addresses the major, so far under-investigated problem related to the completeness of cytoreduction.24, 25, 26 Despite the strict selection criteria usually applied in the more accredited experienced centers, and regardless of the type of PSM, minimal residual disease is a frequent event in patients treated with CRS plus HIPEC and is directly proportional to the PCI.26 Even though minimal residual disease (CC1), with the exception of PSMs from gastric cancer,13,26 is usually considered an acceptable result after CRS plus HIPEC, the outcome depends on several variables, including the biologic aggressiveness of the original PSM, perfusion variables, and chemosensitivity.27,28 Given that survival rates differ significantly between CC0 and CC1 for PSM of gastric or colorectal origin, and differ less in mesothelioma and pseudomyxomas,3,6,13,29 the completeness of cytoreduction is a dynamic concept. Whenever CC0 and CC1 scores yield minor differences in survival, our tool can supply extra, previously unavailable information about the number and sites of residual disease, thus stratifying patients into outcome classes, as others have already suggested for peritoneal mesothelioma.30,31 In patients with minimal residual disease, our digital tool can therefore provide indications for iterative CRS plus HIPEC,32,33 and help in planning further chemotherapy sessions.
Among the possible limitations related to our computerized PSM staging system is convincing those who are used to applying conventional staging classifications and concentrating their efforts on therapy to accept and use a modern digital anatomic tool. These drawbacks will eventually become evident as the surgical groups involved in treating PSM begin to use our online web application. An immediate future direction is to update our anatomic PSM staging system according to the latest research on integrated anatomic–biologic prognostic models.20,34,35
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