Resection margins in modern rectal cancer surgery

Required distal mesorectal resection margin in partial mesorectal excision: a systematic review on distal mesorectal spread

BACKGROUND

The required distal margin in partial mesorectal excision (PME) is controversial. The aim of this systematic review was to determine incidence and distance of distal mesorectal spread (DMS).

METHODS

A systematic search was performed using PubMed, Embase and Google Scholar databases. Articles eligible for inclusion were studies reporting on the presence of distal mesorectal spread in patients with rectal cancer who underwent radical resection.

RESULTS

Out of 2493 articles, 22 studies with a total of 1921 patients were included, of whom 340 underwent long-course neoadjuvant chemoradiotherapy (CRT). DMS was reported in 207 of 1921 (10.8%) specimens (1.2% in CRT group and 12.8% in non-CRT group), with specified distance of DMS relative to the tumor in 84 (40.6%) of the cases. Mean and median DMS were 20.2 and 20.0 mm, respectively. Distal margins of 40 mm and 30 mm would result in 10% and 32% residual tumor, respectively, which translates into 1% and 4% overall residual cancer risk given 11% incidence of DMS. The maximum reported DMS was 50 mm in 1 of 84 cases. In subgroup analysis, for T3, the mean DMS was 18.8 mm (range 8-40 mm) and 27.2 mm (range 10-40 mm) for T4 rectal cancer.

CONCLUSIONS

DMS occurred in 11% of cases, with a maximum of 50 mm in less than 1% of the DMS cases. For PME, substantial overtreatment is present if a distal margin of 5 cm is routinely utilized. Prospective studies evaluating more limited margins based on high-quality preoperative magnetic resonance imaging and pathological assessment are required.

The extent of distal intramural spread of colorectal cancer cell study of it's relationship with histological grading, stage of disease and CEA level

BACKGROUND

The free margin of distal resection is an attempt to prevent local recurrence of the tumor and prolong survival. The recommended length of distal resection margin are varied among the researchers. This study was done to know the correlation between extents of distal intramural spread (DIS) and histology grading, stage and CEA levels of colorectal cancer.

METHODS

The design of the study was a cross sectional. Sample was patients diagnosed with colon or rectal adenocarcinoma in the period of September 2017-March 2018 and underwent resection at Dr.Kariadi Hospital. Resected fresh tissue tumors were directly measured for the distal resection margin and histopathologic examination done by anatomical pathologists. This study has been approved by the ethics committee of Dr.Kariadi Hospital/Faculty of Medicine Diponegoro University. The relationship between DIS length to histology grading, tumor stage and CEA level were analyzed using Spearman's correlation test.

RESULTS

The subjects of this study were 26 patients with colorectal cancer consisted of 15 men and 11 women. The average age of the patients was 53,04 years. The locations of the tumor were 17 in the rectum and 9 in the colon. The length DIS were between 1,07 and 11,49 mm. The longer DIS were occurred when the grading histology worsens, the tumor stage increases and the higher CEA levels with correlation coefficient were r = 0,77 (p < 0,001); r = 0,66 (p < 0,001) and r = 0,44 (p = 0,024) respectively. For the rectal location, the DIS length range were 0,28-10,36 mm. The longer DIS when grading histology worsens r = 0,59 (p = 0,012) and an increased tumor stage r = 0,73 (p = 0,001). The DIS length of the rectum was not proven to correlate with elevated CEA levels r = 0,14 (p = 0,588).

CONCLUSION

Histological grading, tumor stage and CEA levels can be predictors of distal intramural spread (DIS) colorectal cancer. The strongest correlation were between DIS and histologic grading. Thus, in mid and lower third of the rectal cancer, the histologic grade examination is strongly recommended. Based on this study, it is recommended that in rectal cancer undergoing sphincter preserving surgery distal resection sould be more than 2 cm from the tumor margin.

Transanal Total Mesorectal Excision for Treatment of Carcinoma in the Middle or Lower Third Rectum: the Technical Feasibility of the Procedure, Pathological Results, and Clinical Outcome

We are trying to illustrate operative, short-term, and pathological outcomes of transanal total mesorectal excision (TaTME) as a surgical procedure for patients who are suffering cancer in the lower or middle rectum. This study included 25 consecutive patients who underwent TaTME for the mid and low cancer rectum. The primary outcome measures included frequency of postoperative (PO) bleeding, leakage, ileus, days to regain bowel function, days for Foley's removal, and erectile function. The secondary outcome measures included operation time, status of resection margins, number, the quality of TME, and duration PO hospital stay. No recorded intraoperative complications. The mean hospital stay was 6.9 ± 2.6 days. The mean duration need for urinary catheter removal and flatus passage were 2.4 ± 2.1 and 1.5 + 0.9 days, respectively. The mean IPSS was returned to normal 12 months after surgery. The mean distal margin distance was 1.9 ± 1.1. Circumferential margin distance was > 1 mm in 23 (92%) patients. The mesorectum was complete in 22 (88%) patients. The survival rate was 88% over 3 years. TaTME could be considered as a safe, feasible, and effective surgical modality for patients who had mid and lower rectal tumors with an excellent pathological outcome.

The impact of margin status determined by the one-millimeter rule on tumor recurrence and survival following pancreaticoduodenectomy for pancreatic ductal adenocarcinoma

PURPOSE

The tumor-node-metastasis (TNM) classification defines R1 as the presence of tumor cells at the resection margin, while the current Royal College of Pathologists guidelines for pancreaticoduodenectomy specimens regard the presence of tumor cells within 1 mm from the resection margin as R1 (the "1-mm rule"). The aims of this study were to investigate the resection margin status of pancreatic head cancer retrospectively according to both the TNM and 1-mm rule classifications, and to evaluate the postoperative survival and tumor recurrence patterns.

METHODS

A total of 117 patients with pancreatic head cancer were the subjects of this study.

RESULTS

R1^{1-mm rule} resection was associated with a significantly worse disease-free survival (DFS) than R0^{1-mm rule} resection (p = 0.0259), while R1^TNM had no impact on DFS. R1^{1-mm rule} resection margin status correlated with the incidence of tumor recurrence in the liver (p = 0.0483). In a multivariate analysis, R1^{1-mm rule} resection was the independent variable for predicting poor DFS (hazard ratio 1.71; p = 0.0289).

CONCLUSIONS

R1 resection margin status determined by the 1-mm rule may be an independent indicator for predicting disease recurrence, especially liver metastasis. These results may be useful for selecting the appropriate adjuvant therapy protocol and conducting strict surveillance in PDAC patients.

Recurrences in stage II rectal carcinoma after curative resection alone: from the viewpoint of angiogenesis

Background

Angiogenesis plays a pivotal role in malignant tumor progression. The count of blood microvessels of the tumor has been recognized as an indicator of malignant potential of the tumors and provides the ability to predict tumors recurrence. The role endoglin in the Dukes B rectal cancer is still unexplored. The aims of this study were to examine immunohistochemical expression of endoglin in resected rectal cancer and investigate the relationship of tumor recurrence and other clinicopathological variables to the endoglin-assessed microvessel density of the tumor tissue and distal resection margins.

Methods

The study included 95 primary rectal adenocarcinomas, corresponding to 95 distal and 95 proximal resection margin specimens from surgical resection samples. Tumor specimens were paraffin embedded, and immunohistochemical staining for the CD105 endothelial antigen was performed to count CD105-MVD. For exact measurement of the CD105-MVD used, a computer-integrated system Alphelys Spot Browser 2 was used.

Results

The MVD was significantly higher in the tumor samples compared with the distal resection margins (p < 0.0001) and the proximal resection margins (p < 0.0001). There was no significant difference in the MVD between distal and proximal resection margins (p = 0.147). The type of surgical resection was a significant factor for determining the recurrence of tumors (p = 0.0104). There was no significant effect of patients’ age, gender, tumor location, grade of differentiation, histological tumor type, and the size and depth of tumor invasion on the recurrence of the tumor. The recurrence rate was significantly higher in the low CD105-MVD group of patients than in the high CD105-MVD group of patients (log rank test, p = 0.0406). Result of the multivariate analysis showed that the type of surgery (p = 0.0086), MVD tumors (p = 0.0385), and MVD of proximal resection margin (p = 0.0218) were the independent prognostic factors for the recurrent tumors.

Conclusions

CD105-assessed MVD could help to identify patients with more aggressive disease and increased risk of developing tumor recurrence after surgical treatment in stage II rectal cancer (RC).

A Review of the Long-Term Oncologic Outcomes of Robotic Surgery Versus Laparoscopic Surgery for Colorectal Cancer

The goal of this review was to compare long-term oncologic outcomes of robotic versus laparoscopic resection of colorectal cancer. A literature search was performed using PubMed, EMBASE, Cochrane, and Medline (2002-2014). Search terms: laparoscopic, robotic, rectal, colon, surgery, oncologic, and outcomes. Studies comparing overall and disease free survival of robotic versus laparoscopic surgery for colorectal cancer were included. Meta-analysis was performed using OpenMeta[Analyst] for Windows 8. Five studies were identified reporting on overall survival, disease free survival, lymph node extraction, and distal and circumferential resection margin. Three hundred and seventeen patients underwent robotic resection and 368 underwent laparoscopic resection, with similar demographics. Operative times were longer with robotic resections, with no difference in estimated blood loss (EBL) or length of stay. The disease stage was distributed similarly in both groups. Similar numbers underwent neo-adjuvant therapy. Laparoscopic resection was associated with 3.2 mm larger distal resection margins (p = 0.04) and 2.2 more lymph nodes removed (p = 0.001), but with equivalent circumferential resection margin status. Disease-free and overall survival was equivalent. Robotic and laparoscopic surgery for colorectal cancer offer comparable overall and disease free survival. Laparoscopic surgery offered a slight advantage in operative time, distal margin, and lymph node yield. Larger, prospective trials are needed to confirm the equivalence of these approaches.

Robotic versus laparoscopic total mesorectal excision for rectal cancer: a meta-analysis of eight studies

BACKGROUND

Robotic surgery has been used successfully in many branches of surgery, but there is little evidence in the literature on its use in rectal cancer (RC). We conducted this meta-analysis of randomized controlled trials (RCTs) and non-randomized controlled trials (NRCTs) to evaluate whether the safety and efficacy of robotic total mesorectal excision (RTME) in patients with RC are equivalent to those of laparoscopic TME (LTME).

METHODS

Pubmed, Embase, Cochrane Library, Ovid, and Web of Science databases were searched. Studies clearly documenting a comparison of RTME with LTME for RC were selected. Operative and recovery outcomes, early postoperative morbidity, and oncological parameters were evaluated.

RESULTS

Eight studies were identified that included 1229 patients in total, 554 (45.08 %) in the RTME group and 675 (54.92 %) in the LTME group. Compared with LTME, RTME was associated with lower conversion rate (OR 0.23, 95 % CI [0.10, 0.52]; P = 0.0004), lower positive rate of circumferential resection margins (CRM) (2.74 % vs 5.78 %, OR 0.44, 95 % CI [0.20, 0.96], P = 0.04), and lesser incidence of erectile dysfunction (ED) (OR 0.09, 95 % CI [0.02, 0.41]; P = 0.002). Operation time, estimated blood loss, recovery outcome, postoperative morbidity and mortality, length of hospital stay, number of lymph nodes harvested, distal resection margin (DRM), proximal resection margin (PRM), and local recurrence had no significant differences between the two groups.

CONCLUSIONS

RTME is safe and feasible and may be an alternative treatment for RC. More international multicenter prospective large sample RCTs investigating the long-term oncological and functional outcomes are needed to determine the advantages of RTME over LTME in RC.

Anastomotic Leakage after Anterior Resection for Rectal Cancer with Mesorectal Excision: Incidence, Risk Factors, and Management

We investigated risk factors and prognostic implications of symptomatic anastomotic leakage after anterior resection for rectal cancer, and the influence of a diverting stoma. Our retrospective review of prospective collected data analyzed 475 patients who underwent anterior resection for rectal cancer. Uni- and multivariate analysis was made between anastomotic leakage and patient, tumor, and treatment variables, either for the overall group (n = 475) and in the midlow rectal cancer subgroup (n = 291). Overall rate of symptomatic leakage was 9 per cent (43 of 475) with no related postoperative mortality. At univariate analysis, significant factors for leak were a tumor less than 6 cm from the anal verge (13.7 vs 6.6%; P = 0.011) and intraoperative transfusions (16.9 vs 4.3%; P = 0.001). Similar results were observed in the midlow rectal cancer subgroup. At multivariate analysis, no parameter resulted in being an independent prognostic factor for risk of leakage. In patients with a leakage, a temporary enterostomy considerably reduced the need for reoperation (12.5 vs 77.8%; P < 0.0001) and the risk of a permanent stoma (18.7 vs 28.5%; P = 0.49). The incidence of anastomotic failure increases for lower tumors, whereas it is not influenced by radiotherapy. Defunctioning enterostomy does not influence the leak rate, but it mitigates clinical consequences.

Sphincter preservation in distal CT2N0 rectal cancer after preoperative chemoradiotherapy

BACKGROUND

Preoperative chemoradiotherapy is usually not indicated for cT2N0 rectal cancer. Abdominoperineal resection is the standard treatment for distal rectal tumors. The aim of the study was to evaluate the actual sphincter-preservation rate in patients with distal cT2N0 rectal cancer given neoadjuvant chemoradiotherapy.

METHODS

Data were retrospectively collected for all patients who were diagnosed with distal cT2N0 rectal cancer at a tertiary medical center in 2000-2008 and received chemoradiotherapy followed by surgery (5-7 weeks later).

RESULTS

Thirty-three patients (22 male) of median age 65 years (range, 32-88) were identified. Tumor distance from the anal verge ranged from 0 to 5 cm. R0 resection with sphincter preservation was accomplished in 22 patients (66%), with a 22% pathological complete response rate. Median follow-up time was 62 months (range 7-120). There were no local failures. Crude disease-free and overall survival were 82% and 86%, respectively. Factors associated with sphincter preservation were tumor location (OR=0.58, p=0.02, 95% CI=0.37-0.91) and pathological downstaging (OR=7.8, p=0.02, 95% CI=1.35-45.85). Chemoradiotherapy was well tolerated.

CONCLUSION

High rates of sphincter preservation can be achieved after preoperative chemoradiotherapy for distal cT2N0 rectal cancer, with tolerable toxicity, without compromising oncological outcome.

Interval to surgery after neoadjuvant treatment for colorectal cancer

The current standard treatment of low-lying locally advanced rectal cancer consists of chemoradiation followed by radical surgery. The interval between chemoradiation and surgery varied for many years until the 1999 Lyon R90-01 trial which compared the effects of a short (2-wk) and long (6-wk) interval. Results showed a better clinical tumor response (71.7% vs 53.1%) and higher rate of positive and pathologic tumor regression (26% vs 10.3%) after the longer interval. Accordingly, a 6-wk interval between chemoradiation and surgery was set to balance the oncological results with the surgical complexity. However, several recent retrospective studies reported that prolonging the interval beyond 8 or even 12 wk may lead to significantly higher rates of tumor downstaging and pathologic complete response. This in turn, according to some reports, may improve overall and disease-free survival, without increasing the surgical difficulty or complications. This work reviews the data on the effect of different intervals, derived mostly from retrospective analyses using a wide variation of treatment protocols. Prospective randomized trials are currently ongoing.

Robotic versus laparoscopic total mesorectal excision for rectal cancer: a meta-analysis

BACKGROUND

Robotic surgery has been used successfully in many branches of surgery; but there is little evidence in the literature on its use in rectal cancer (RC). We conducted this meta-analysis that included randomized controlled trials and nonrandomized controlled trials of robotic total mesorectal excision (RTME) versus laparoscopic total mesorectal excision (LTME) to evaluate whether the safety and efficacy of RTME in patients with RC are equivalent to those of LTME.

MATERIALS AND METHODS

Pubmed, Embase, Cochrane Library, Ovid, and Web of Science databases were searched. Studies clearly documenting a comparison of RTME with LTME for RC were selected. Operative and recovery outcomes, early postoperative morbidity, and oncological parameters were evaluated.

RESULTS

Eight studies were identified that included 1229 patients in total, 554 (45.08%) in the RTME and 675 (54.92%) in the LTME. Meta-analysis suggested that the conversion rate to open surgery in RTME was significantly lower than in LTME (P = 0.0004). There were no significant differences in operation time, estimated blood loss, recovery outcome, postoperative morbidity and mortality, length of hospital stay, and the oncological accuracy of resection and local recurrence between the two groups. The positive rate of circumferential resection margins (P = 0.04) and the incidence of erectile dysfunction (P = 0.002) were lower in RTME compared with LTME.

CONCLUSIONS

RTME for RC is safe and feasible, and the short- and medium-term oncological and functional outcomes are equivalent or preferable to LTME. It may be an alternative treatment for RC. More multicenter randomized controlled trials investigating the long-term oncological and functional outcomes are required to determine the advantages of RTME over LTME in RC.

Total mesorectal excision: a comparison of oncological and functional outcomes between robotic and laparoscopic surgery for rectal cancer

BACKGROUND

Long-term data from the CLASICC study demonstrated the oncologic equivalence of laparoscopic and open rectal cancer surgery despite an increased circumferential resection margin involvement in the laparoscopic group in the initial report. Moreover, laparoscopic total mesorectal excision (TME) may be associated with increased rates of male sexual dysfunction compared to conventional open TME. Robotic surgery could potentially obtain better results than laparoscopy. The aim of this study was to compare the clinical and functional outcomes of robotic and laparoscopic surgery in a single-center experience.

METHODS

This study was based on 100 patients who underwent minimally invasive anterior rectal resection with TME. Fifty consecutive robotic rectal anterior resections with TME (R-TME) were compared to the first 50 consecutive laparoscopic rectal resections with TME (L-TME).

RESULTS

Median operative time was 270 min in R-TME and 275 min in L-TME. No conversions occurred in the R-TME group whereas six conversions occurred in the L-TME group. The mean number of harvested lymph nodes was 16.5 ± 7.1 for R-TME and 13.8 ± 6.7 for L-TME. The circumferential margin (CRM) was <2 mm in six L-TME patients, whereas no one in R-TME group had a CRM <2 mm. The International Prostate Symptom Score (IPSS) scores were significantly increased 1 month after surgery in both the L-TME and R-TME groups, but they normalized 1 year after surgery. Erectile function worsened significantly 1 month after surgery in both the groups but it was restored completely 1 year after surgery in the R-TME group and partially in the L-TME group.

CONCLUSIONS

Robotic TME is oncologically safe and adequate for rectal cancer treatment, showing better results than laparoscopic TME in terms of CRM, conversions, and hospital length of stay. Better recovery in voiding and sexual function is achieved with the robotic technique.

Microscopically positive margins for primary gastrointestinal stromal tumors: analysis of risk factors and tumor recurrence

BACKGROUND

Little is known about the outcomes of patients with microscopically positive (R1) resections for primary gastrointestinal stromal tumors (GIST) because existing retrospective series contain small numbers of patients. The objective of this study was to analyze factors associated with R1 resection and assess the risk of recurrence with and without imatinib.

STUDY DESIGN

We reviewed operative and pathology reports for 819 patients undergoing resection of primary GIST from the North American branch of the American College of Surgeons Oncology Group (ACOSOG) Z9000 and Z9001 clinical trials at 230 institutions testing adjuvant imatinib after resection of primary GIST. Patient, tumor, operative characteristics, factors associated with R1 resections, and disease status were analyzed.

RESULTS

Seventy-two (8.8%) patients had an R1 resection and were followed for a median of 49 months. Factors associated with R1 resection included tumor size (≥ 10 cm), location (rectum), and tumor rupture. The risk of disease recurrence in R1 patients was driven largely by the presence of tumor rupture. There was no significant difference in recurrence-free survival for patients undergoing an R1 vs R0 resection of GIST with (hazard ratio [HR] 1.095, 95% CI 0.66, 1.82, p = 0.73) or without (HR 1.51, 95% CI 0.76, 2.99, p = 0.24) adjuvant imatinib.

CONCLUSIONS

Approximately 9% of 819 GIST patients had an R1 resection. Significant factors associated with R1 resection include tumor size ≥ 10 cm, location, and rupture. The difference in recurrence-free survival with or without imatinib therapy in those undergoing an R1 vs R0 resection was not statistically significant at a median follow-up of 4 years.

Violation of treatment guidelines -- hazard for rectal cancer patients

AIM

The aim of this study was to evaluate temporal trends in treatment and outcome in rectal cancer diagnosed during 1980-2004 at Levanger Hospital.

MATERIALS AND METHODS

A protocol for prospective registration of rectal cancer treated with total mesorectal excision including operative strategy, radiotherapy and surveillance was established at Levanger Hospital in 1980. In this study, all rectal cancer patients treated during 1980-2004 were included.

RESULTS

More patients received preoperative radiotherapy during 2000-2004, but otherwise there were no significant differences in presentation or treatment during 1980-2004. The 5-year local recurrence rate after resection with curative intent was 4.5% (0-9.7), 18.7% (10.3-27.1) and 2.2% (0-6.7) in 1980-1989, 1990-1999 and 2000-2004 (p = 0.006), respectively. Out of a total of 23 cases of local recurrence, treatment guidelines, mainly with regard to radiotherapy, were violated in 19 cases. The 5-year overall survival after resection with curative intent was 65% (95% confidence interval [CI] 55-76) during 1980-1989, 58% (49-68) in 1990-1999 and 71% (59-83) in 2000-2004 (n.s). The 5-year relative survival was 83% (95% CI 69-95) during 1980-1989, 71% (59-81) in 1990-1999 and 84% (69-98) in 2000-2004 (n.s).

CONCLUSION

Rectal cancer patients experienced excellent outcomes in the period 1980-1989 and 2000-2004. Due to violations of treatment guidelines, the rate of local recurrence was much too high in the period 1990-1999. This article illustrates the importance of continuous quality assurance in the treatment of rectal cancer to maintain optimized outcomes for the patients.

Patterns of local recurrence in rectal cancer after a multidisciplinary approach

Improvements in surgery and the application of combined approaches to fight rectal cancer have succeeded in reducing the local recurrence (LR) rate and when there is LR it tends to appear later and less often in isolation. Moreover, a subtle change in the distribution of LRs with respect to the pelvis has been observed. In general terms, prior to total mesorectal excision the most common LRs were central types (perianastomotic and anterior) while lateral and posterior forms (presacral) have become more common since the growth in the use of combined treatments. No differences have been reported in the current pattern of LRs as a function of the type of approach used, that is, neo-adjuvant therapies (short-term or long-course radiotherapy, or chemoradiotherapy versus extended lymphadenectomy, though there is a trend towards posterior or presacral LR in patients in the Western world and lateral LR in Asia. Nevertheless, both may arise from the same mechanism. Moreover, as well as the mode of treatment, the type of LR is related to the height of the initial tumor. Nowadays most LRs are related to the advanced nature of the disease. Involvement of the circumferential radial margin and spillage of residual tumor cells from lymphatic leakage in the pelvic side wall are two plausible mechanisms for the genesis of LR. The patterns of pelvic recurrence itself (pelvic subsites) also have important implications for prognosis and are related to the potential success of salvage curative approach. The re-operability for cure and prognosis are generally better for anastomotic and anterior types than for presacral and lateral recurrences. Overall survival after LR diagnosis is lower with radio or chemoradiotherapy plus optimal surgery approaches, compared to optimal surgery alone.

Detection limits of intraoperative near infrared imaging for tumor resection

BACKGROUND AND OBJECTIVES

The application of fluorescent molecular imaging to surgical oncology is a developing field with the potential to reduce morbidity and mortality. However, the detection thresholds and other requirements for successful intervention remain poorly understood. Here we modeled and experimentally validated depth and size of detection of tumor deposits, trade-offs in coverage and resolution of areas of interest, and required pharmacokinetics of probes based on differing levels of tumor target presentation.

METHODS

Three orthotopic tumor models were imaged by widefield epifluorescence and confocal microscopes, and the experimental results were compared with pharmacokinetic models and light scattering simulations to determine detection thresholds.

RESULTS

Widefield epifluorescence imaging can provide sufficient contrast to visualize tumor margins and detect tumor deposits 3-5  mm deep based on labeled monoclonal antibodies at low objective magnification. At higher magnification, surface tumor deposits at cellular resolution are detectable at TBR ratios achieved with highly expressed antigens.

CONCLUSIONS

A widefield illumination system with the capability for macroscopic surveying and microscopic imaging provides the greatest utility for varying surgical goals. These results have implications for system and agent designs, which ultimately should aid complete resection in most surgical beds and provide real-time feedback to obtain clean margins.

Positive mobilization margins alone do not influence survival following pancreatico-duodenectomy for pancreatic ductal adenocarcinoma

OBJECTIVE

To determine the prognostic influence of residual tumor at or within 1 mm of the mobilization margins (R1Mobilization) compared with transection margins (R1Transection) following pancreaticoduodenectomy for pancreatic ductal adenocarcinoma (PDAC).

BACKGROUND

The prognostic strength of R1 status increases with frequency of margin positivity and is enhanced by protocol driven pathology reporting. Currently, margins are treated uniformly with tumor at or close to any margin considered of equal prognostic significance. The resection involves a mobilization phase freeing the posterior margin and anterior surface then a transection phase requiring lympho-vascular division forming the medial resection and pancreatic transection margin. The comparative assessment of the relative importance of tumor involvement of these different margins has not previously been investigated.

METHODS

Retrospective analysis of 148 consecutive resections for PDAC from 1996-2007 was performed. The individual (pancreatic transection, medial, posterior, and anterior surface) margins were separately identified and analyzed by a senior pathologist. An R1 resection was defined as microscopic evidence of tumor < or = 1 mm from a resection margin. R1Mobilization tumor extension included both R1Anterior and R1Posterior cases; while R1Transection included pancreatic neck/body transection, R1Medial and adjacent transection margins.

RESULTS

R1 status was confirmed in 109 patients (74%). The medial (46%) and posterior (44%) margins were most commonly involved. R1 status was found to an independent predictor of poor outcome (P < 0.001). R1Mobilization involvement only (n = 48) was associated with a significantly longer median survival of 18.9 months (95% CI, 13.7-24.8) versus 11.1 months (95% CI, 7.1-15.0) for those with R1Transection tumor involvement (n = 61) (P < 0.001). There was no significant difference in the survival of the R1Mobilization compared with R0 group (P = 0.52).

CONCLUSIONS

Following pancreaticoduodenectomy for PDAC, involvement of the transection margins in contrast to mobilization margins defines a group whose outcome is significantly worse. This may impact upon the allocation of adjuvant therapy within the setting of randomized controlled trials.

Endocavitary thermal therapy by MRI-guided phased-array contact ultrasound: experimental and numerical studies on the multi-input single-output PID temperature controller's convergence and stability

PURPOSE

Endocavitary high intensity contact ultrasound (HICU) may offer interesting therapeutic potential for fighting localized cancer in esophageal or rectal wall. On-line MR guidance of the thermotherapy permits both excellent targeting of the pathological volume and accurate preoperatory monitoring of the temperature elevation. In this article, the authors address the issue of the automatic temperature control for endocavitary phased-array HICU and propose a tailor-made thermal model for this specific application. The convergence and stability of the feedback loop were investigated against tuning errors in the controller's parameters and against input noise, through ex vivo experimental studies and through numerical simulations in which nonlinear response of tissue was considered as expected in vivo.

METHODS

An MR-compatible, 64-element, cooled-tip, endorectal cylindrical phased-array applicator of contact ultrasound was integrated with fast MR thermometry to provide automatic feedback control of the temperature evolution. An appropriate phase law was applied per set of eight adjacent transducers to generate a quasiplanar wave, or a slightly convergent one (over the circular dimension). A 2D physical model, compatible with on-line numerical implementation, took into account (1) the ultrasound-mediated energy deposition, (2) the heat diffusion in tissue, and (3) the heat sink effect in the tissue adjacent to the tip-cooling balloon. This linear model was coupled to a PID compensation algorithm to obtain a multi-input single-output static-tuning temperature controller. Either the temperature at one static point in space (situated on the symmetry axis of the beam) or the maximum temperature in a user-defined ROI was tracked according to a predefined target curve. The convergence domain in the space of controller's parameters was experimentally explored ex vivo. The behavior of the static-tuning PID controller was numerically simulated based on a discrete-time iterative solution of the bioheat transfer equation in 3D and considering temperature-dependent ultrasound absorption and blood perfusion.

RESULTS

The intrinsic accuracy of the implemented controller was approximately 1% in ex vivo trials when providing correct estimates for energy deposition and heat diffusivity. Moreover, the feedback loop demonstrated excellent convergence and stability over a wide range of the controller's parameters, deliberately set to erroneous values. In the extreme case of strong underestimation of the ultrasound energy deposition in tissue, the temperature tracking curve alone, at the initial stage of the MR-controlled HICU treatment, was not a sufficient indicator for a globally stable behavior of the feedback loop. Our simulations predicted that the controller would be able to compensate for tissue perfusion and for temperature-dependent ultrasound absorption, although these effects were not included in the controller's equation. The explicit pattern of acoustic field was not required as input information for the controller, avoiding time-consuming numerical operations.

CONCLUSIONS

The study demonstrated the potential advantages of PID-based automatic temperature control adapted to phased-array MR-guided HICU therapy. Further studies will address the integration of this ultrasound device with a miniature RF coil for high resolution MRI and, subsequently, the experimental behavior of the controller in vivo.

Multicolor fluorescent intravital live microscopy (FILM) for surgical tumor resection in a mouse xenograft model

Background

Complete surgical resection of neoplasia remains one of the most efficient tumor therapies. However, malignant cell clusters are often left behind during surgery due to the inability to visualize and differentiate them against host tissue. Here we establish the feasibility of multicolor fluorescent intravital live microscopy (FILM) where multiple cellular and/or unique tissue compartments are stained simultaneously and imaged in real time.

Methodology/Principal Findings

Theoretical simulations of imaging probe localization were carried out for three agents with specificity for cancer cells, stromal host response, or vascular perfusion. This transport analysis gave insight into the probe pharmacokinetics and tissue distribution, facilitating the experimental design and allowing predictions to be made about the localization of the probes in other animal models and in the clinic. The imaging probes were administered systemically at optimal time points based on the simulations, and the multicolor FILM images obtained in vivo were then compared to conventional pathological sections. Our data show the feasibility of real time in vivo pathology at cellular resolution and molecular specificity with excellent agreement between intravital and traditional in vitro immunohistochemistry.

Conclusions/Significance

Multicolor FILM is an accurate method for identifying malignant tissue and cells in vivo. The imaging probes distributed in a manner similar to predictions based on transport principles, and these models can be used to design future probes and experiments. FILM can provide critical real time feedback and should be a useful tool for more effective and complete cancer resection.