The Primary Research Of Imging And Molecular Pathology In Distal Spread Of Rectal Cancer

BackgroundAccording to the studies on the anatomy and pathophysiology of rectrum and rectal cancer. Dr. Heald introduced the concept of mesorectrum and total mesorectal excision(TME) which is one of the largest improvements in the outcome of rectal cancer in 1980s'. TME with its large decline in local recurrence rate, has become the new standard of operative management for rectal cancers, replacing conventional resection technique. Recent reports revealed that the distal spread was rarely in the rectal cancer. Studies on resected rectal specimens suggest that distal spread in the mesorectum were rarely and often limited in a short distance to the macroscopic primary tumor. The resection margins were small furthermore. More and more low rectal cancer was performed preserve-sphincter excision. New concept that patients without infiltration of the external sphincter should be performed this conservative surgery is accepted by most surgeons. However, many investigators doubted that the preserve-sphincter excision for low rectal cancer might result in unclarified selection process. As a result, the resection margin is still argued at present.There are several approaches to pre-operation evaluation for rectal cancer excision. But imageologic evaluation is of most importment. The development of instrument and the exploitation of medical software led us to get more exact understand the pre-operation situation for rectal cancer. Relatively speaking,PET/CT scan was of most value in the cancer diagnosis, pre-operation staging and follow-up of post-operation. However, that if PET/CT imaging impacts on the distal spread of rectal cancer and the preserve-sphincter excision has still no yet reported literaturely. The purpose of this study is to examine the extent and significance of microscopic distal spread from a clinicopathologic viewpoint and PET/CT imaging and to determine the safety and optimal distal margin of resection in the sphincter reserving operation.Materials and methodsThe preparation of the rectal specimens45 cases with mid-low rectal cancer were examined and marked with two deep venous ducts on the anal margin of the tumor. The venous duct was about 0.5~1cm long. The distance between two markers was measured from PET/CT imaging. After TME surgery, the operative specimen was examined and cut lengthwise along the opposite side of the tumor. Gently drag the specimen and keep the distance between two markers as the same of the measurement from the PET/CT imaging. Pinning out the specimen, collected from the primary cancer and from normal mucosa at 10cm proximal the cancer margin as the positive and negative control. The various distal portion section with 0.5cm long to the cancer margin also collected from the distal cancer margin to 0.5cm, 0.5cm~1cm, 1cm~1.5cm, 1.5cm~2.0cm and 2.0cm~2.5cm. Ascertaining the point where SUV is 2.5 in the operative specimen. Obtained the PET/CT positive portion section from the cancer margin to the point and the distal negative portion section for the same length to the point. All samples were routinely fixed and imbedded.The routine pathology examination on distal tissue of rectal cancer1.The routine pathology examination were taken for all tissue portion and positive and negative portion using routine H.E stain technique.2.Molecular pathology examination on distal tissue of rectal cancerP53 and CD34 express were detected and compared adopting immunohistochenical stain.(1)P53 and CD34 expression in rectal cancer and distal mucosa to cancer marginP53 expression in rectal cancer and distal mucosa to cancer marginCD34 expression in rectal cancer and distal mucosa to cancer margin(2)Expression of P53 and distribution of CD34 expression in different kinds of rectal cancer P53 expression in different kinds of rectal cancerCD34 expression in different kinds of rectal cancer(3)The relationship between the size of the tumor and expression of P53 and CD34 in each tissueThe relationship between the size of the tumor and expression of P53 in each tissueThe relationship between the size of the tumor and expression of CD34 in each tissue(4)Expression of P53 and CD34 in each rectal cancer stagingExpression of P53 in each rectal cancer stagingExpression of CD34 in each rectal cancer staging PET/CT imaging of rectal cancer1. PET/CT imaging of rectal cancer and reconstruction2. Ascertainment of the distal PET positive portion to cancer margin3. Expression of P53 and CD34 in PET/CT positive and negative portion4. The relationship between the length of PET positive portion and oncology of rectal cancer ResultsThe routine pathology examination on distal tissue of rectal cancerIn 45 cases, the distal spread was founded in only one case in first 5mm distal portion.P53 and CD34 expression in rectal cancer and distal mucosa to cancer margin1. P53 expression in rectal cancer and distal mucosa to cancer marginP53 expression in rectal cancer was significantly higher than that in distal mucosa to cancer margin. It decreased in distal mucosa along the anal direction. But it was still founded in the negative control rectal tissue. P53 expression was not significantly different between in more than 1.5cm distal rectal mucosa and in negative control rectal tissue.2. CD34 expression in rectal cancer and distal mucosa to cancer marginMVD in rectal cancer was significantly higher than that in distal mucosa to cancer margin. It decreased in distal mucosa along the anal direction. But CD34 was still founded in the negative control rectal tissue. MVD was not significantly different between in more than 1cm distal rectal mucosa and in negative control rectal tissue. The distribution curve of P53 expression was similar to that of MVD in rectal cancer and in distal mucosa. But the degree of decreasing between P53 expression and MVD was not the same. P53 expression was normal in more than 1.5cm distal rectal mucosa and MVD in more than 1cm distal rectal mucosa.Expression of P53 and distribution of CD34 expression in different kinds of rectal cancer1. P53 expression in different kinds of rectal cancerP53 expression in each portion tissue was not associated with differentiation of rectal cancer.2. CD34 expression in different kinds of rectal cancerThe distribution of MVD in each portion tissue was not associated with differentiation of rectal cancer. The relationship between the size of the tumor and expression of P53 and CD34 in each tissue1.The relationship between the size of the tumor and expression of P53 in each tissue P53 expression in each portion tissue was not correlated with size of the rectal cancer2.The relationship between the size of the tumor and expression of CD34 in each tissueMVD in less than 0.5cm distal rectal mucosa between larger size tumor which was more than 3cm and smaller size tumor was significantly different. It was higher in larger size tumor than in small size tumor. However, it in more than 0.5cm distal rectal mucosa was not associated with size of tumor. The distribution of MVD was a little different with that of P53 expression.Expression of P53 and CD34 in each rectal cancer staging1. Expression of P53 in each rectal cancer stagingExpression of P53 in rectal caner and each distal portion tissue was not correlated with stage of the rectal cancer2. Expression of CD34 in each rectal cancer stagingMVD in rectal caner and each distal portion tissue was not correlated with stage of the rectal cancer PET/CT imaging of rectal cancer1. Ascertainment of the distal PET positive portion to cancer marginThe distance from cancer anal margin to the distal positive portion where SUV was 2.5 is 4mm~12mm, averagely 7.0±2.0mm.2.Expression of P53 and CD34 in PET positive and negative portionExpression of P53 and CD34 in PET positive portion was significantly higher than PET negative portion3. The relationship between the length of PET positive portion and oncology of rectal cancerThe length of distal PET positive portion was not associated with size, kind and staging of rectal cancer.ConclusionsAccording to pathologic detection, the distal spread was found only in few cases.The morphological and histochemical abnormality was found in distal mucosa of rectal cancer. The distribution of P53 expression and MVD was not completely similar to each other.Expression of P53 and CD34 in PET positive portion was significantly higher than PET negative portion Bath morphological and histochemical significant abnormality located in 1.5cm distal mucosa. The preoperative evaluation of particular parameters related to DIS enabled the accurate selection of rectal cancer to which the two-centimeter rule of distal clearance can be applied.PET/CT imaging might be a woundless and macroscopic parameter to predict resection margin and to expand the indication of sphincter preservation for low rectal adenocarcinoma patients.