Research Article	Contribution of PET/CT in Determining Lymph Node Metastasis Before Low Anterior Resection Aşağı Anterior Rezeksiyon Öncesi Lenf Nodu Metastazının Belirlenmesinde PET/BT'nin Katkısı *Meriç Emre BOSTANCI^1[ID], Zekiye HASBEK^2[ID], Onur MAHMUTOĞLU^3[ID], Kürşat KARADAYI^4 [ID] Abstract The aim of this study was to evaluate the sensitivity of ^18F-FDG (fluorodeoxyglucose) PET/CT (positron emission tomography / computed tomography) imaging performed for primary staging prior to surgery performed with the low anterior resection technique in detecting the presence of lymph node metastases detected in the mesorectal area. In our retrospective study, 44 patients who were operated for colorectal cancer in our Surgical Oncology Department between June 15, 2015 and June 15, 2020 and who underwent ^18F-FDG PET/CT for preoperative staging were included. The demographic data of the patients were obtained from the records were taken during routine clinical interrogations before both surgery and PET/CT scan, and from the automation system records of our hospital. While 12 (27.3%) of the patients had vascular invasion, 32 (72.7%) did not. While 15 (34.1%) of the patients had perineural invasion, 29 (65.9%) did not. Histopathologically, the rates of lymph node metastasis were high in patients with vascular invasion and perineural invasion (p=0.005 and p=0.012, respectively). There was no significant relationship between the SUVmax value of the primary tumor in PET/CT and the presence/absence of lymph node metastasis histopathologically determined (p=0.405). The median tumor size of the primary mass lesion was 4 cm (15-150 mm). No significant correlation was found between tumor size and presence/absence of lymph node metastasis (p=0.587). Sensitivity of CT is 68.7%, specificity 44.4%, accuracy 55.8%, positive predictive value 52.3%, negative the predictive value was 61.5%; whereas the sensitivity of ^18F-FDG PET/CT was found to be 78.9%, specificity 50%, accuracy 63.6%, positive predictive value 55.5%, negative predictive value 76.4%. In conclusion, despite advanced imaging techniques, it will not be possible to be sure of the presence/absence of metastatic lymph nodes without radical surgery. We think that PET/CT imaging has also an important place in determining distant lymph node metastases other than regional lymph node spread. Keywords: Low Anterior Resection, Lymph Node Metastasis, PET/CT. Özet Bu çalışmada amacımız, aşağı anterior rezeksiyon tekniği ile yapılan cerrahi operasyon öncesi primer evreleme amacıyla yapılan ^18F-FDG (florodeoksiglikoz) PET/BT (pozitron emisyon tomografi / bilgisayarlı tomografi) görüntülemesinin mezorektal alanda tespit edilen lenf nodu metastazlarının varlığını tespit etmedeki duyarlılığını değerlendirmektir. Retrospektif olan çalışmamıza 15 Haziran 2015 ve 15 Haziran 2020 tarihleri arasında Cerrahi Onkoloji Bilim Dalımızda kolorektal kanser nedeniyle opere edilen, cerrahi öncesi evreleme amacıyla ^18F-FDG PET/BT yapılan 44 hasta dahil edildi. Hastalara ait demografik veriler hem cerrahi hem de PET/BT çekimi öncesi rutin klinik sorgulamalar sırasında yapılan kayıtlardan ve hastanemiz otomasyon sistemi kayıtlarından elde edildi. Hastalardan 12’sinde (%27.3) damar invazyonu varken, 32’sinde (%72.7) yoktu. Hastalardan 15’inde (%34.1) perinöral invazyon varken, 29’unda (%65.9) yoktu. Histopatolojik olarak damar invazyonu ve perinöral invazyonu olan hastalarda lenf nodu metastazı görülme oranları yüksekti (p=0.005 ve p=0.012, sırasıyla). PET/BT’de primer tümöre ait SUVmax değeri ile histopatolojik olarak tespit edilen lenf nodu metastazı varlığı/yokluğu arasında anlamlı ilişki bulunmadı (p=0.405). Primer kitle lezyonunun median tümör boyutu 4 cm (15-150 mm) idi. Tümör boyutu ile lenf nodu metastazı varlığı/yokluğu arasında da anlamlı ilişki bulunmadı (p=0.587). BT’nin sensitivitesi %68.7, spesifitesi %44.4, doğruluğu %55.8, pozitif prediktif değeri %52.3 ve negatif prediktif değeri %61.5 iken; ^18F-FDG PET/BT’nin sensitivitesi %78.9, spesifitesi %50, doğruluğu %63.6, pozitif prediktif değeri %55.5 ve negatif prediktif değeri %76.4 olarak bulunmuştur. Sonuç olarak, gelişmiş görüntüleme tekniklerine rağmen radikal cerrahi yapılmadan metastatik lenf nodu varlığından/yokluğundan emin olunamayacaktır. PET/BT görüntülemenin bölgesel lenf nodu yayılımı dışında uzak lenf nodu metastazlarının belirlenmesinde de önemli bir yeri olduğunu düşünmekteyiz. Anahtar kelimeler: Aşağı anterior rezeksiyon, Lenf nodu metastazı, PET/BT. Introduction According to Globocan 2018 data, colorectal cancers (CRC) constitute 10.2% of all cancers, and cancers developing from the rectum and rectosigmoid region constitute approximately thirty percent of all colorectal cancers [1]. Quality oncological surgical treatment is essential for optimal treatment responses in these cancers, and the type of surgical treatment varies depending on the location of the tumor. The rectum is roughly divided into three parts as the upper, middle and lower rectum. While the lower rectum is extraperitoneal, only the anterior face is covered by the peritoneum in the middle rectum. In the upper rectum, the anterior and lateral faces are covered with the peritoneum. Low anterior resection (LAR) is one of the standard surgical techniques used in the surgical treatment of cancers located in the middle rectum and 1/3 of the upper rectum. The LAR technique is a surgical technique that defines the transabdominal removal of tumor tissue after resection of the rectum in which the anastomosis level remains below the peritoneal reflection. With this technique, the sigmoid colon and its meso are dissected so that it is 2 cm below the tumor. Rectum and entire mesorectum are resected. The splenic flexure and left half of the transverse column are freed by dissections to reduce the tension that may occur in the anastomosis. When the colorectal anastomosis is performed with the help of a circular stapler, the rings removed from the stapler tip are controlled. It is very important for the safety of the anastomosis that these rings are completely circular and contain all layers in the intestinal wall. In case of tension in the anastomosis, when it is not sure that the ends of the anastomosis are vascularized, and in cases such as anastomosis in the distal area very close to the anal canal, the patient can be opened a loop ileostomy or colostomy as anastomosis protection [2,3]. Nowadays, there is a significant decrease in the local recurrence rates of these cancers thanks to multidisciplinary approaches and the algorithms of adjuvant and neoadjuvant treatments besides oncological surgery. Despite this, high local recurrence rates are still reported due to incomplete resection [4]. Unlike many other types of cancer, surgical treatment plays an important role in colorectal cancers, especially in the invasive group, even in advanced stages, due to the risks of obstruction, hemorrhage and perforation. It is important to evaluate the presence/absence of extramesorectal lymph node metastases in rectal cancers both before and after surgery and neoadjuvant therapy. In fact, the actual staging of colorectal cancers is usually done according to the pathological examination of the specimens removed after surgery. Our aim in this study is to evaluate the sensitivity of 18F-FDG (fluorodeoxyglucose) PET/CT (positron emission tomography / computed tomography) imaging performed for primary staging prior to surgery performed with the low anterior resection technique in detecting the presence of lymph node metastases detected in the mesorectal area. To read more, see the pdf format of the article ...
DOI: 10.46683/jmvi.2024.89
Article in English
^1Department of Surgical Oncology, Sivas Numune Hospital, Sivas, Türkiye. ^2Department of Nuclear Medicine, Sivas Cumhuriyet University Faculty of Medicine, Sivas, Türkiye. ^3Sivas Provincial Health Directorate, Republic of Türkiye Ministry of Health, Sivas, Türkiye. ^4Department of Surgical Oncology, Sivas Cumhuriyet University Faculty of Medicine, Sivas, Türkiye.
*Corresponding author Meriç Emre Bostancı; MD., Department of Surgical Oncology, Sivas Numune Hospital, Sivas, Türkiye. E-mail: drmericemrebostanci@gmail.com
Received: 27.03.2024 Accepted: 11.04.2024 Published: 12.04.2024
Cite as: Bostancı ME, Hasbek Z, Mahmutoğlu O, Karadayı K. Contribution of PET/CT in Determining Lymph Node Metastasis Before Low Anterior Resection. J Mol Virol Immunol 2024; 5(2): 34-39.
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