Resectional surgery for malignant disease of abdominal digestive organs is not surgery of the organ itself, but also that of the mesenteric organ

Despite large strides in molecular oncology, surgery remains the bedrock in the management of visceral cancer. The primacy of surgery cannot be understated and a mesenteric (i.e. ontogenetic) approach is particularly beneficial to patients. Heald greatly advanced the management of rectal cancer with his description of the anatomical foundation of total mesorectal excision (TME), dramatically improving outcomes worldwide with this mesenteric-based approach. Moreover, complete mesocolic excision (CME) based on similar principles is becoming popular. Introduced by Hohenberger, CME resembles TME insofar as it emphasises strictly anatomical dissection along embryological planes to detach an intact (i.e. “complete”) mesentery with peritoneal envelope. CME also incorporates “central” vascular ligation (CVL) which broadly correlates with the “D3 lymphadenectomy” of Eastern literature. As many surgeons already practise anatomical and mesenteric-based surgery, it is unclear how the putative benefits of CME (including CVL) arise. Herein, we argue that these may relate to a more extensive resection of the mesentery, and thus mesenteric tumour deposits within the connective tissue lattice of the mesentery, and not necessarily the lymphadenectomy alone. We believe the connective tissue interface between the bowel wall and mesentery provides an alternative mode of spread of pathogenic elements. Whilst this remains a suggestion only, it would explain the histological independence of tumour deposits and why a greater mesenterectomy could be associated with benefits in survival. If this argument holds, it follows that resectional surgery for digestive organ malignancy is not surgery of the organ itself (or lymphatics only), but also that of the contiguous mesentery.

The relationship between mesorectal grading and oncological outcome in rectal adenocarcinoma

AIM

The prognostic association between mesorectal grading and oncological outcome in patients undergoing resection for rectal adenocarcinoma is controversial. The aim of this retrospective chart review was to determine the individual impact of mesorectal grading on rectal cancer outcomes.

METHOD

We compared oncological outcomes in patients with complete, near-complete and incomplete mesorectum who underwent rectal excision with curative intent from 2009 to 2014 for Stage cI-III rectal adenocarcinoma. We also assessed the independent association of mesorectal grading and oncological outcome using multivariate models including other relevant variables.

RESULTS

Out of 505 patients (339 men, median age of 60 years), 347 (69%) underwent a restorative procedure. There were 452 (89.5%), 33 (6.5%) and 20 (4%) patients with a complete, near-complete and incomplete mesorectum, respectively. Local recurrence was seen in 2.4% (n = 12) patients after a mean follow-up of 3.1 ± 1.7 years. Unadjusted 3-year Kaplan-Meier analysis by mesorectal grade showed decreased rates of overall, disease-free and cancer-specific survival and increased rates of overall and distant recurrence with a near-complete mesorectum, while local recurrence was increased in cases of an incomplete mesorectum (all P < 0.05). On multivariate analyses, a near-complete mesorectum was independently associated with decreased cancer-specific survival (hazard ratio 0.26, 95% CI 0.1-0.7; P = 0.007). There were no associations between mesorectal grading and overall survival, disease-free survival, overall recurrence or distant recurrence (all P > 0.05).

CONCLUSION

Mesorectal grading is independently associated with oncological outcome. It provides unique information for optimizing surgical quality in rectal cancer.

Colorectal surveillance after segmental resection for young-onset colorectal cancer: is there evidence for extended resection?

AIM

Although sporadic colorectal cancer (CRC) usually occurs in patients aged over 50, recent evidence suggests that the incidence is increasing in younger patients. Such patients are theoretically at high risk of metachronous neoplasia and may be candidates for extended prophylactic colectomy. This study aimed to define the risk of metachronous cancer/adenomas during follow-up of younger patients who underwent segmental colectomy for CRC.

METHOD

A CRC database was used to identify patients aged under 50 who underwent surgery for CRC between 1994 and 2010. Patients diagnosed with hereditary cancer or inflammatory bowel disease were excluded. The primary end-points were frequency of extended resection and the rates of metachronous cancer and high-risk adenomas during follow-up.

RESULTS

There were 284 young patients with a resectable primary tumour, of whom 280 (98.6%) underwent segmental resection, 3 (1%) extended resection and 1 (0.4%) local resection. Endoscopic follow-up was available for 150 of the patients who had segmental colectomy, with a mean age of 42.6 (±5.8) years at diagnosis and median follow-up time of 68 months (interquartile range 45-105). Out of these 150 patients, 4 (2.7%) developed metachronous colonic adenocarcinoma at 24, 71, 151 and 228 months after index surgery. Thirty additional patients had at least one adenoma identified during surveillance, and three had sessile serrated polyps. Out of the three patients undergoing extended resection, none had metachronous cancer or advanced adenomas at an average follow-up of 17 years.

CONCLUSION

A segmental colectomy or proctectomy is adequate treatment for patients presenting with CRC under the age of 50.

Assessment of a novel, full-thickness incisional biopsy model to restage rectal tumours after neoadjuvant chemoradiotherapy: results of an ex vivo pilot study

BACKGROUND

There is currently no reliable means to restage rectal cancers after neoadjuvant chemoradiation. Recent histological evidence shows that the epicentre for residual cancer cells is focussed directly underneath any residual mucosal abnormality (RMA). This proof-of-concept study aimed to determine the utility of a novel, minimally invasive method of incisional biopsy as a restaging tool. A secondary aim was to compare its performance to clinical response assessment.

METHODS

After surgical resection, 0.5 × 0.5 cm, full-thickness incisional biopsy was performed in 15 rectal cancers. Of these, 13 had RMA and 2 had mucosal cCR but a palpable intramural abnormality. In all patients, a full-thickness incisional biopsy was taken through the centre of these areas. The ypT stage of the incisional biopsy and the final total specimen were compared. Complete mucosal clinical response was deemed to have occurred when either no residual tumour or only a flat mucosal scar remained.

RESULTS

Incisional biopsy correctly identified all patients that had been downstaged to ypT0; however, it also falsely identified 5 of 10 patients (50%) with yp residual disease as ypT0. Overall performance of incisional biopsy to detect residual cancer was 50% sensitivity, 100 % specificity, 100% PPV, and 50% NPV with an accuracy of 66%. A complete mucosal clinical response occurred in only one of five patients downstaged to ypT0 (20% sensitive). It also occurred in one patient, which was ultimately staged as ypT3.

CONCLUSION

This prospective data demonstrates that incisional biopsy is not suitable as a stand-alone method to restage rectal cancer after CRT. Alternate or complementary means of restaging are needed.

Genotype-defined cancer risk in juvenile polyposis syndrome

Background

Germline mutations in SMAD4 and BMPR1A disrupt the transforming growth factor β signal transduction pathway, and are associated with juvenile polyposis syndrome. The effect of genotype on the pattern of disease in this syndrome is unknown. This study evaluated the differential impact of SMAD4 and BMPR1A gene mutations on cancer risk and oncological phenotype in patients with juvenile polyposis syndrome.

Methods

Patients with juvenile polyposis syndrome and germline SMAD4 or BMPR1A mutations were identified from a prospectively maintained institutional registry. Medical records were reviewed and the clinical patterns of disease were analysed.

Results

Thirty-five patients had germline mutations in either BMPR1A (8 patients) or SMAD4 (27). Median follow-up was 11 years. Colonic phenotype was similar between patients with SMAD4 and BMPR1A mutations, whereas SMAD4 mutations were associated with larger polyp numbers (number of patients with 50 or more gastric polyps: 14 versus 0 respectively). The numbers of patients with rectal polyps was comparable between BMPR1A and SMAD4 mutation carriers (5 versus 17). No patient was diagnosed with cancer in the BMPR1A group, whereas four men with a SMAD4 mutation developed gastrointestinal (3) or extraintestinal (1) cancer. The gastrointestinal cancer risk in patients with juvenile polyposis syndrome and a SMAD4 mutation was 11 per cent (3 of 27).

Conclusion

The SMAD4 genotype is associated with a more aggressive upper gastrointestinal malignancy risk in juvenile polyposis syndrome.

Depth and lateral spread of microscopic residual rectal cancer after neoadjuvant chemoradiation: implications for treatment decisions

AIM

The aim of this study was to determine the distribution of residual tumour within the bowel wall in relation to residual mucosal abnormalities (RMAs) and surrounding normal mucosa in patients with rectal cancer who underwent neoadjuvant chemoradiation followed by curative surgery.

METHOD

Archived pathological slides from a cohort of 60 patients with residual tumour were retrieved. The incidence, distance and depth of tumour spread (ypT) under RMAs and adjacent normal mucosa were reviewed and recorded.

RESULTS

Histological sections containing both RMA and adjacent normal mucosa were available for 45 of 60 patients with ypT1 (n = 6), ypT2 (n = 18) and ypT3 (n = 21) disease. The maximal depth of invasion, as measured by ypT stage, was found underneath the RMA in 44 of 45 (98%) patients. Microscopic tumour spread lateral to the RMA and under adjacent normal mucosa was found in 32 of 45 (71%) patients. The median and maximum distances of lateral spread for ypT1 tumours were 0 and 4 mm; for ypT2 were 2.5 and 9 mm; and for ypT3 were 4 and 9 mm respectively.

CONCLUSION

Lateral tumour spread under normal mucosa adjacent to RMAs is a common finding and extended up to 9 mm in this study. The epicentre for maximum depth of invasion was directly underneath the RMAs in nearly all cases. These data have clinical and technical implications if local excision is to be considered.

Gene expression profile is associated with chemoradiation resistance in rectal cancer

AIM

Patients with rectal cancer who achieve a complete pathological response after preoperative chemoradiation (CRT) have an improved oncological outcome. Identifying factors associated with a lack of response could help our understanding of the underlying biology of treatment resistance. This study aimed to develop a gene expression signature for CRT-resistant rectal cancer using high-throughput nucleotide microarrays.

METHOD

Pretreatment biopsies of rectal adenocarcinomas were prospectively collected and freshly frozen according to an institutional review board-approved protocol. Total tumour mRNA was extracted and gene expression levels were measured using microarrays. Patients underwent proctectomy after completing standard long-course CRT and the resected specimens were graded for treatment response. Gene expression profiles for nonresponders were compared with those of responders. Differentially expressed genes were analyzed for functional significance using the Ingenuity Pathway Analysis (IPA) software.

RESULTS

Thirty-three patients treated between 2006 and 2009 were included. We derived 812-gene and 183-gene signatures separating nonresponders from responders. The classifiers were able to identify nonresponders with a sensitivity and specificity of 100% using the 812-gene signature, and sensitivity and specificity of 33% and 100% using the 183-gene signature. IPA canonical pathway analysis revealed a significant ratio of differentially expressed genes in the 'DNA double-strand break repair by homologous recombination' pathway.

CONCLUSION

Certain rectal cancer gene profiles are associated with poor response to CRT. Alterations in the DNA double-strand break repair pathway could contribute to treatment resistance and provides an opportunity for further studies.

BRAF mutation is associated with distinct clinicopathological characteristics in colorectal cancer: a systematic review and meta-analysis

AIM

Colorectal cancer is a heterogeneous disease with multiple underlying genetic mutations resulting in different phenotypes. Mutation in the v-Raf murine sarcoma viral oncogene homolog B1 (BRAF) proto-oncogene is an important event in the methylator pathway. There is no consensus, however, on the clinicopathological characteristics associated with BRAF mutation.

METHOD

A comprehensive search for published studies examining the effect of BRAF mutation on colorectal cancer was performed. Random effects methods were used to combine data.

RESULTS

Data were retrieved from 21 studies describing 9885 patients. BRAF associated colorectal cancer is associated with proximal tumour location (OR 5.222, 95% CI 3.801-7.174, P < 0.001), T4 tumours (OR 1.761, 95% CI 1.164-2.663, P = 0.007) and poor differentiation (OR 3.816, 95% CI 2.714-5.365, P < 0.001) and is negatively associated with male sex (OR 0.623, 95% CI 0.505-0.769, P < 0.001), age of diagnosis under 60 years (OR 0.453, 95% CI 0.280-0.733, P = 0.001) and rectal cancer (OR 0.266, 95% CI 0.122-0.422, P < 0.001).

CONCLUSION

BRAF mutation appears to be associated with distinct, unfavourable clinicopathological characteristics in colorectal cancer.

Results from an American Society of Colon and Rectal Surgeons survey on the management of young-onset colorectal cancer

BACKGROUND

Young patients with colorectal cancer (CRC) present a diagnostic and clinical challenge. The aim of our study was to survey the approaches to preoperative evaluation and clinical management of young patients with CRC by colorectal surgeons in North America.

METHODS

A standard electronic survey was sent to the members of the American Society of Colon and Rectal Surgeons. The survey polled management decisions in various clinical scenarios for CRC patients less than 50 years old. Survey responses were collated and analyzed.

RESULTS

One hundred ninety surgeons responded and 140 completed the entire survey (response rate 10%). Eighty percent of surgeons would offer preoperative genetic testing if the patient's family met the Amsterdam criteria compared to only 67% if the criteria were not met. Of those offering preoperative tumor testing, 48% test microsatellite instability, 19% mismatch repair protein expression by immunohistochemistry, and 24% offer both. Decisions regarding the extent of the resection for cancer were dependent on family history: Most members (86%) would perform a segmental colectomy for CRC in a patient without family history. Eighty-four percent of respondents would offer a total abdominal colectomy if preoperative tests indicated Lynch syndrome. When questioned about MYH-associated polyposis, only 27% recognized the appropriate diagnosis.

CONCLUSIONS

Among the American Society of Colon and Rectal Surgeons, family history influences preoperative testing and surgical management decisions. A significant portion of surgeons do not offer preoperative genetic testing, despite implications on operative management, postoperative surveillance, and screening of family members.

Serrated polyp detection rate during screening colonoscopy

AIM

The adenoma detection rate is an important quality indicator for colonoscopy, but recently, serrated polyps of the large bowel have been recognized as important premalignant lesions. As they are often more difficult to see than adenomas, the detection rate of serrated polyps is set to become a more stringent indicator of quality in colonoscopy than adenoma detection rate. Here we aim to provide preliminary data on serrated polyp detection.

METHOD

This is a retrospective review of prospectively collected data. Colonoscopies were stratified by one of six colorectal surgeons, each of whom had performed more than 1000 colonoscopies. Exams were separated by indication and the number of patients with at least one adenoma or one serrated polyp recorded. Time of withdrawal in normal examinations was noted.

RESULTS

Eighteen thousand and three colonoscopies were included. Average completion rate was 96.3 ± 1.2%. Mean serrated detection rate for all examinations was 20.6 ± 4.8% and for screening examinations only was 13.9 ± 5.0%. Corresponding means for adenoma detection were 31.5 ± 6.7% and 20.7 ± 4.1%, respectively. Simple regression of overall adenoma detection rate versus overall serrated detection rate was not significant (R = 0.571, P = 0.237), but was significant for screening exams (R = 0.854, P = 0.031). There was a strong relationship between time of withdrawal and serrated detection rate (screening, R = 0.908, P = 0.012; overall, R = 0.956, P = 0.003).

CONCLUSION

Taking time to withdraw the colonoscope is essential for maximum detection of serrated polyps. The ability to find adenomas does not necessarily correlate with an ability to find serrated polyps.

Serrated polyps: new classifications highlight clinical importance

AIM

Many lesions previously classified as hyperplastic polyps and therefore thought to be innocuous have been reclassified as sessile serrated adenomas/polyps (SSA/Ps), establishing their place in the serrated pathway and underscoring their malignant potential. The clinical relevance of this new nomenclature is incompletely defined. This study examines the incidence and characteristics of colorectal SSA/Ps and describes other associated colorectal neoplasia.

METHOD

A single institution pathology database was searched for the diagnosis of SSA/Ps between January 2004 and October 2007. SSA/Ps found by colonoscopy were included. Patient demographics, SSA/P characteristics and associated colonoscopic findings were retrospectively recorded.

RESULTS

A total of 585 SSA/Ps were removed during 519 colonoscopies in 483 patients performed by 64 different endoscopists. This represented an overall incidence of SSA/Ps per colonoscopy of 2.1% in the 28,054 colonoscopies performed during the study period. The median SSA/P size was 0.8 cm (range 0.2-4.5) and 188 (69%) were ≥ 1.0 cm. Of the 585 SSA/Ps, 366 (63%) were right-sided, 129 (22%) were in the left colon and 90 (15%) were in the rectum. Also, 439 synchronous polyps of other histology (mainly adenomas and hyperplastic polyps) were found during the same 519 colonoscopies.

CONCLUSION

SSA/Ps are rare lesions found during colonoscopy that may coexist with small hyperplastic polyps. Because SSA/Ps are part of the serrated oncogenic pathway, all, even those appearing to be hyperplastic, should be removed or biopsied for diagnosis. Careful review of historical lesions with application of new definitions may redefine risk for malignancy.

Clinical implications of acellular mucin pools in resected rectal cancer with pathological complete response to neoadjuvant chemoradiation

AIM

Approximately 20% of rectal cancers treated with neoadjuvant chemoradiation achieve a pathological complete response (pCR), which is associated with an improved oncological outcome. However, in a proportion of patients with a pCR, acellular pools of mucin are present in the surgical specimen. The aim of this study was to evaluate the clinical implications of acellular mucin pools in patients with rectal adenocarcinoma achieving a pCR after neoadjuvant chemoradiation followed by proctectomy.

METHOD

A single-centre colorectal cancer database was searched for patients with clinical Stage II and Stage III rectal adenocarcinoma who achieved a pCR (i.e. ypT0N0M0) after neoadjuvant chemoradiation followed by proctectomy between 1997 and 2007. Patients were categorized according to the presence or absence of acellular mucin pools in the resected specimen, and groups were compared. Patient demographics, tumour and treatment characteristics, and oncological outcomes were recorded. Primary outcomes were 3-year local and distant recurrences, and disease-free and overall survivals.

RESULTS

Two hundred and fifty-eight patients with clinical Stage II or Stage III rectal adenocarcinoma were treated by neoadjuvant chemoradiation. Fifty-eight of these patients had a 58 pCR. Eleven of the 58 patients with a pCR had acellular mucin pools in the surgical specimen. The median follow up was 40 months. The groups were statistically similar with respect to demographics, chemoradiation regimens, distance of tumour from the anal verge, clinical stage and surgical procedure. No patient had local recurrence. Patients with acellular mucin pools had increased distant recurrence (21%vs 5%), decreased disease-free survival (79%vs 95%) and decreased overall survival (83%vs 95%) rates, although none of these differences was statistically significant.

CONCLUSION

The presence of acellular mucin pools in a proctectomy specimen with a pCR does not affect local recurrence, but may suggest a more aggressive tumour biology.

Genetic and epigenetic classifications define clinical phenotypes and determine patient outcomes in colorectal cancer

BACKGROUND

A molecular classification of colorectal cancer has been proposed based on microsatellite instability (MSI), CpG island methylator phenotype (CIMP), and mutations in the KRAS and BRAF oncogenes. This study examined the prevalence of these molecular classes, and differences in clinical presentation and outcome.

METHODS

Demographics, tumour characteristics and survival were recorded for 391 subjects with colorectal cancer. Tumour DNA was analysed for MSI (high (MSI-H) or microsatellite stable (MSS)), CIMP (high (CIMP-H) or no (CIMP-neg)) and BRAF and KRAS mutations. Clinical differences between four phenotypes were examined.

RESULTS

Most tumours were MSS/CIMP-neg (69.8 per cent), with a nearly equal distribution of MSI-H/CIMP-H, MSI-H/CIMP-neg and MSS/CIMP-H types. MSS/CIMP-neg tumours were less likely to be poorly differentiated (P = 0.009). CIMP-H tumours were more common in older patients (P < 0.001). MSI-H/CIMP-H tumours had a high frequency of BRAF mutation and a low rate of KRAS mutation; the opposite was true for MSS/CIMP-neg tumours (P < 0.001). The four molecular phenotypes tended towards divergent survival (P = 0.067 for stages 1-III). MSI-H cancers were associated with better disease-free survival (hazard ratio 2.00 (95 per cent confidence interval 1.03 to 3.91); P = 0.040).

CONCLUSION

Colorectal cancers are molecularly and clinically heterogeneous. These different molecular phenotypes may reflect variable prognosis.

Fever evaluations after colorectal surgery: identification of risk factors that increase yield and decrease cost

PURPOSE

This study was designed to evaluate the yield and cost of fever evaluations in average-risk inpatients after elective colorectal surgery.

METHODS

A 12-month, retrospective study was performed on patients who developed a postoperative fever > or = 38 degrees C after elective colorectal surgery. A positive fever evaluation was defined as a blood culture, urine culture, chest x-ray, or abdominal CT result that led to a change in patient management. Logistic regression, Fisher's exact test, and chi-squared test were used; odds ratios were calculated.

RESULTS

Of 133 patients, 26 percent had a positive evaluation. Blood culture, urine culture, chest x-ray, and CT were positive in 3, 8, 7, and 46 percent, respectively. Risk factors for a positive fever evaluation were temperature > or = 38.5 degrees C, fever evaluation after postoperative Day 6, and a clinical manifestation of systemic inflammatory response syndrome other than fever (all, P < 0.01). The cost per positive fever evaluation for the entire group, patients with 2 risk factors, or patients with 3 risk factors was $5,600, $4,200, and $2,140, respectively.

CONCLUSIONS

The current approach to fever evaluation after elective colorectal surgery is low yield and costly. High fever, late postoperative fever, and systemic inflammatory response syndrome are risk factors for a positive fever evaluation after colorectal surgery.

Laparoscopic adrenalectomy for pheochromocytoma

BACKGROUND

Laparoscopic adrenalectomy is a safe and effective treatment for most surgical diseases of the adrenal gland. However it has been suggested that catecholamine effects associated with pheochromocytoma render the laparoscopic approach a more challenging and a more morbid procedure. The purpose of this study was to compare the operative characteristics and outcomes of laparoscopic adrenalectomy for pheochromocytoma to those of aldosteronoma and incidentaloma.

METHOD

Patient records and operative reports were retrospectively reviewed for demographics, diagnoses, operative management, and outcomes for patients undergoing laparoscopic adrenalectomy between June 1994 and July 2002 at two academic medical centers. A total of 74 patients were included and analyzed by diagnosis. Differences were considered statistically significant at p < 0.05.

RESULTS

Twenty-eight patients with pheochromocytoma, 27 with aldosteronoma, and 19 with incidentally discovered nonfunctioning adrenal masses underwent laparascopic adrenalectomy. Patients undergoing resection for pheochromocytoma trended toward more operative blood loss (150 ml) compared to aldosteronoma (88 ml) and incidentaloma (75 ml). Eight patients were converted to an open procedure for a 10.8% conversion rate. The mean operative time was 171 min and there was a 10.8% perioperative complication rate. The mean hospital stay was 3.4 days. These results were not statistically significant between diagnostic groups.

CONCLUSION

Despite concern about increased operative times and morbidity associated with pheochromocytoma, our experience supports that laparoscopic adrenalectomy may be performed as safely as, and achieve outcomes similar to, those for other diseases.

Validation of delayed sentinel lymph node mapping for melanoma

PURPOSE

Sentinel lymph node mapping using radiolabeled tracer and blue dye is widely accepted and applied for staging melanoma. Common practice involves injection of radiolabeled tracer on the morning of surgery. However, optimal timing of radiolabeled colloid injection with respect to surgery remains debated. Injection on the day before surgery would offer the advantages of increased scheduling flexibility and decreased radiation exposure to the patient and operating room staff. We hypothesized that a single injection of radiolabeled colloid given 24 hours before surgery would be sufficient and would possibly improve intraoperative sentinel lymph node identification.

PATIENTS AND METHODS

Ninety-five patients with newly diagnosed cutaneous melanoma underwent injection of radiolabeled colloid and lymphoscintigraphy 18 to 24 hours before surgery for sentinel lymph node mapping and biopsy. Sixty-three patients underwent repeat imaging immediately before surgery, and the images were compared with those obtained the previous day. Intraoperative mapping utilized a hand-held gamma probe and injection of blue dye to identify sentinel lymph nodes.

RESULTS

Two hundred fifty-one sentinel lymph nodes were identified by initial lymphoscintigraphy in 95 patients. Delayed imagingwithout reinjection of radiolabeled tracer compared with the initial lymphoscintigraphy demonstrated no change (71%), clarification of initial ambiguous patterns (10%), or newly identified nodes (19%). Two hundred sixty-one sentinel lymph nodes were resected, of which 79% stained blue. Microscopic metastases were present in 20 sentinel lymph nodes (8%) in 19 patients (20%). All positive nodes contained radioactivity and blue dye.

CONCLUSIONS

A single injection of radiocolloid 24 hours before surgery combined with intraoperative blue dye injection identified all sentinel lymph nodes and did not miss any metastatic disease. In addition, delayed imaging may clarify initial ambiguous findings and identify additional nodes at risk for metastasis. This technique produces sentinel lymph node identification rates, harvest rates, and rates of positivity comparable to those reported with the use of injection of radiolabeled tracer on the day of surgery and greatly facilitates the technical and administrative aspects of sentinel lymph node mapping.

Immediate and long-term outcomes after lateral pancreaticojejunostomy for chronic pancreatitis

Lateral pancreaticojejunostomy (LPJ) is the recommended surgical treatment of intractable pain from chronic pancreatitis (CP) with obstruction and ductal dilatation. This study evaluated the etiology, morbidity, mortality, hospital costs, and quality of life (QL) for patients with LPJ for CP. Medical records of 60 patients undergoing LPJ for CP between 1988 and 1996 were reviewed. Long-term QL was assessed by the Short Form 36 Health Survey and analyzed against control populations of patients who underwent pancreatic debridement for necrosis and patients with laparoscopic cholecystectomy for cholelithiasis. CP etiologies included 52 per cent alcoholic, 28 per cent idiopathic, 13 per cent pancreatic divisum, and 7 per cent familial pancreatitis. Peri- and postoperative morbidity and mortality were 25 and 0 per cent respectively. Average hospital cost was $13,530 with mean postoperative hospital stay of 12.1 days. Overall physical and mental QL were diminished compared with both the debridement group and cholecystectomy group with particular detriments in areas of physical role (P < 0.05), bodily pain (P < 0.001), social function (P < 0.001), and mental health (P < 0.001). We conclude that LPJ for CP is a relatively safe procedure with low morbidity and mortality but results in a significantly diminished long-term QL relative to other surgical patients with pancreatic or biliary disease. This difference prevails in both physical and mental aspects of health.

Decreased fibrinolytic activity in porcine-to-primate cardiac xenotransplantation

BACKGROUND

One major barrier to successful xenotransplantation is acute vascular rejection, a process pathologically characterized by microvascular thrombosis and diffuse fibrin deposition in transplant blood vessels. This pathologic picture may result from a disturbance in the coagulant or fibrinolytic pathways that regulate normal vascular patency. This study evaluated the regulation of fibrinolytic activity defined by tissue plasminogen activator and plasminogen activator inhibitor-1 as it may exist in the setting of acute vascular rejection.

MATERIALS AND METHODS, RESULTS

Serial biopsies from cardiac xenotransplants evaluated by immunofluorescence microscopy demonstrated progressive decreases in tissue plasminogen activator and increases in plasminogen activator inhibitor-1. In vitro studies measuring fibrinolytic activity of cell culture medium from porcine aortic endothelial cells stimulated with human serum or autologous porcine serum revealed that human serum triggered as much as 93% increase in antifibrinolytic activity.

CONCLUSIONS

These findings demonstrate that porcine vascular endothelial cells change toward an antifibrinolytic state following stimulation with human xenoreactive antibodies and complement. The shift is at least partly explained by an increased ratio of plasminogen activator inhibitor-1 to tissue plasminogen activator, and is at least in part mediated by the activation of complement. This increased antifibrinolytic activity may contribute to the thrombotic diathesis seen in acute vascular rejection in pig-to-primate xenografts.

Identification of a human rasGAP-related protein containing calmodulin-binding motifs

Conversion of active GTP-bound Ras to its inactive GDP-bound form is catalyzed by GTPase-activating proteins (GAPs). Two mammalian Ras-specific GAPs, p120GAP and neurofibromin, the product of the NF1 tumor suppressor gene, have been previously described. We report here the identification of a new human cDNA clone, IQGAP1, which predicts a 1657-amino acid protein that displays extensive sequence similarity to the catalytic domain of all previously reported RasGAPs. IQGAP1 is most closely related to the Schizosaccharomyces pombe RasGAP-like protein, Sar1. Sequence similarity to IQGAP1 is seen throughout the entire Sar1 protein. The N-terminal half of IQGAP1, which does not overlap with Sar1, contains six copies of a unique amino acid motif, as well as four so-called IQ motifs. The latter motifs are found in several proteins, including conventional and unconventional myosins, and mediate the interaction with calmodulin and calmodulin-related proteins. Thus, IQGAP1 appears to represent a novel RasGAP-like protein that may link Ras signaling to some calmodulin-mediated process.