Brendan C. Visser

Single-cell dissection of transcriptional heterogeneity in human colon tumors.

Cancer is often viewed as a caricature of normal developmental processes, but the extent to which its cellular heterogeneity truly recapitulates multilineage differentiation processes of normal tissues remains unknown. Here we implement single-cell PCR gene-expression analysis to dissect the cellular composition of primary human normal colon and colon cancer epithelia. We show that human colon cancer tissues contain distinct cell populations whose transcriptional identities mirror those of the different cellular lineages of normal colon. By creating monoclonal tumor xenografts from injection of a single (n = 1) cell, we demonstrate that the transcriptional diversity of cancer tissues is largely explained by in vivo multilineage differentiation and not only by clonal genetic heterogeneity. Finally, we show that the different gene-expression programs linked to multilineage differentiation are strongly associated with patient survival. We develop two-gene classifier systems (KRT20 versus CA1, MS4A12, CD177, SLC26A3) that predict clinical outcomes with hazard ratios superior to those of pathological grade and comparable to those of microarray-derived multigene expression signatures.

Characterization of cystic pancreatic masses: Relative accuracy of CT and MRI

OBJECTIVE The objective of our study was to determine the role and relative accuracy of CT and MRI in the characterization of cystic pancreatic masses. MATERIALS AND METHODS We retrospectively identified 58 patients with histopathologically proven cystic pancreatic masses at our institution who underwent preoperative CT (n = 40), MRI (n = 6), or both (n = 12). Two radiologists independently recorded their leading diagnoses with levels of diagnostic certainty (0-100%), their estimates of overall likelihood of malignancy (0-100%), and the morphologic characteristics of the tumors. Data were analyzed to determine relative accuracy in the diagnosis of malignancy, relationship between diagnostic certainty and accuracy, and frequency of malignancy in unilocular thin-walled cysts smaller than 4 cm. RESULTS Twenty-one (36%) of 58 masses were malignant. CT and MRI were equally accurate in establishing the diagnosis of malignancy (area under the receiver operating characteristic curve [A(z)] = 0.91 and 0.85 for reviewers 1 and 2 at MRI vs 0.82 and 0.76 at CT, respectively; p > 0.05). The leading diagnosis given by reviewers 1 and 2 was correct in 46% (32/70) and 43% (30/70) of the studies, respectively. When reviewer diagnostic certainty was 90% or more, the corresponding values were not significantly (p > 0.05) improved at 55% (12/22) and 48% (10/21), respectively. Two (15%) of 13 unilocular thin-walled cysts smaller than 4 cm were frankly malignant. CONCLUSION CT and MRI are reasonably and similarly accurate in the characterization of cystic pancreatic masses as benign or malignant; limitations include a substantial rate of misdiagnosis even when reviewer certainty is high and a moderate frequency of malignancy in small morphologically benign-appearing cysts.

Changing management of gallstone disease during pregnancy

AbstractBackground: Symptomatic gallstones may be problematic during pregnancy. The advisability of laparoscopic cholecystectomy (LC) is uncertain. The objective of this study is to define the natural history of gallstone disease during pregnancy and evaluate the safety of LC during pregnancy. Methods: Review of medical records of all pregnant patients with gallstone disease at the University of California, San Francisco, from 1980 to 1996. Results: Of approximately 29,750 deliveries, 47 (0.16%) patients were treated for gallstone disease, including biliary colic in 33, acute cholecystitis in 12, and pancreatitis in two. Conservative treatment was attempted in all patients but failed in 17 (36%) cases. Two patients required combined preterm Cesarean-section cholecystectomy and 10 required surgery in the early postpartum period for persistent symptoms. Seventeen patients required cholecystectomy during pregnancy for biliary colic (10), acute cholecystitis (six), and pancreatitis (one). Three patients were treated with open cholecystectomy. Fourteen patients underwent LC at a mean gestational age of 18.6 weeks, mean OR time of 74 min, and mean length of stay of 1.2 days. Hasson cannulation was utilized in 11 patients. Reduced-pressure pneumoperitoneum (6–10 mmHg) was used in seven patients. Prophylactic tocolytics were used in seven patients, with transient postoperative preterm labor observed in one. There were no open conversions, preterm deliveries, fetal loss, teratogenicity, or maternal morbidity. Conclusions: In past years, symptomatic gallstones during pregnancy were managed conservatively or with open cholecystectomy. LC is a feasible and safe method for treating severely symptomatic patients.

Safety and Timing of Nonobstetric Abdominal Surgery in Pregnancy

Background/Aims: Abdominal disorders occurring during pregnancy pose special difficulties in diagnosis and management to the obstetrician and surgeon. The advisability of nonobstetric abdominal surgery during pregnancy is uncertain. Our objective was to evaluate the safety and timing of abdominal surgery during pregnancy. Methods: We retrospectively reviewed 77 consecutive gravid patients undergoing nonobstetric abdominal surgery from 1989 to 1996 at an urban academic medical center and a large affiliated community teaching hospital. Medical records were evaluated for clinical presentation, perioperative management, preterm labor, and maternal and fetal morbidity and mortality. Results: The rate of nonobstetric abdominal surgery during pregnancy was 1 in every 527 births. Among the 77 patients, the indications for surgery were adnexal mass (42%), acute appendicitis (21%), gallstone disease (17%) and other (21%). There was no maternal or fetal loss or identifiable neonatal birth defect. Preterm labor occurred in 26% of the second-trimester patients and 82% of the third-trimester patients. Preterm labor was most common in patients with appendicitis and after adnexal surgery. Preterm delivery occurred in 16% of the patients, but appeared to be directly related to the abdominal surgery in only 5%. Conclusion: Surgery during the first or second trimester is not associated with significant preterm labor, fetal loss or risk of teratogenicity. Surgery during the third trimester is associated with preterm labor, but not fetal loss.

Noninvasive monitoring of diffuse large B-cell lymphoma by immunoglobulin high-throughput sequencing

Recent studies have shown limited utility of routine surveillance imaging for diffuse large B-cell lymphoma (DLBCL) patients achieving remission. Detection of molecular disease by immunoglobulin high-throughput sequencing (Ig-HTS) from peripheral blood provides an alternate strategy for surveillance. We prospectively evaluated the utility of Ig-HTS within 311 blood and 105 tumor samples from 75 patients with DLBCL, comparing Ig-HTS from the cellular (circulating leukocytes) and acellular (plasma cell-free DNA) compartments of peripheral blood to clinical outcomes and (18)fluoro-deoxyglucose positron emission tomography combined with computed tomography (PET/CT; n = 173). Clonotypic immunoglobulin rearrangements were detected in 83% of patients with adequate tumor samples to enable subsequent monitoring in peripheral blood. Molecular disease measured from plasma, compared with circulating leukocytes, was more abundant and better correlated with radiographic disease burden. Before treatment, molecular disease was detected in the plasma of 82% of patients compared with 71% in circulating cells (P = .68). However, molecular disease was detected significantly more frequently in the plasma at time of relapse (100% vs 30%; P = .001). Detection of molecular disease in the plasma often preceded PET/CT detection of relapse in patients initially achieving remission. During surveillance time points before relapse, plasma Ig-HTS demonstrated improved specificity (100% vs 56%, P < .0001) and similar sensitivity (31% vs 55%, P = .4) compared with PET/CT. Given its high specificity, Ig-HTS from plasma has potential clinical utility for surveillance after complete remission.

Pancreatic endocrine tumors with major vascular abutment, involvement, or encasement and indication for resection.

BACKGROUND Surgery for pancreatic endocrine tumors (PETs) with blood vessel involvement is controversial. HYPOTHESIS Resection of PETs with major blood vessel involvement can be beneficial. DESIGN The combined databases of the National Institutes of Health and Stanford University hospitals were queried. MAIN OUTCOME MEASURES Operation, pathologic condition, complications, and disease-free and overall survival. RESULTS Of 273 patients with PETs, 46 (17%) had preoperative computed tomography evidence of major vascular involvement. The mean size for the primary PET was 5.0 cm. The involved major vessel was as follows: portal vein (n = 20), superior mesenteric vein or superior mesenteric artery (n = 16), inferior vena cava (n = 4), splenic vein (n = 4), and heart (n = 2). Forty-two of 46 patients had a PET removed: 12 (27%) primary only, 30 (68%) with lymph nodes, and 18 (41%) with liver metastases. PETs were removed by either enucleation (n = 7) or resection (n = 35). Resections included distal or subtotal pancreatectomy in 23, Whipple in 10, and total in 2. Eighteen patients had concomitant liver resection: 10 wedge resection and 8 anatomic resections. Nine patients had vascular reconstruction: each had reconstruction of the superior mesenteric vein and portal vein, and 1 had concomitant reconstruction of the superior mesenteric artery. There were no deaths, but 12 patients had complications. Eighteen patients (41%) were immediately disease free, and 5 recurred with follow-up, leaving 13 (30%) disease-free long term. The 10-year overall survival was 60%. Functional tumors were associated with a better overall survival (P < .001), and liver metastases decreased overall survival (P < .001). CONCLUSION These findings suggest that surgical resection of PETs with vascular abutment/invasion and nodal or distant metastases is indicated.

Distinct biological subtypes and patterns of genome evolution in lymphoma revealed by circulating tumor DNA

Circulating tumor DNA reveals patterns of clonal evolution and allows classification of tumor subtypes in lymphoma. The telltale DNA in lymphoma Diffuse large B cell lymphoma is a relatively common type of tumor that can exhibit a wide range of behaviors, from indolent and curable cancers to ones that are very aggressive and difficult to treat. By analyzing DNA in tumor samples and blood of lymphoma patients, Scherer et al. have shown that specific genetic characteristics can determine each tumor’s cell of origin and identify tumors that are going to transform into more aggressive subtypes and may require more intensive treatment. The authors also demonstrated that circulating tumor DNA in the patients’ blood is suitable for this analysis, allowing for periodic monitoring of each patient without repeated invasive biopsies. Patients with diffuse large B cell lymphoma (DLBCL) exhibit marked diversity in tumor behavior and outcomes, yet the identification of poor-risk groups remains challenging. In addition, the biology underlying these differences is incompletely understood. We hypothesized that characterization of mutational heterogeneity and genomic evolution using circulating tumor DNA (ctDNA) profiling could reveal molecular determinants of adverse outcomes. To address this hypothesis, we applied cancer personalized profiling by deep sequencing (CAPP-Seq) analysis to tumor biopsies and cell-free DNA samples from 92 lymphoma patients and 24 healthy subjects. At diagnosis, the amount of ctDNA was found to strongly correlate with clinical indices and was independently predictive of patient outcomes. We demonstrate that ctDNA genotyping can classify transcriptionally defined tumor subtypes, including DLBCL cell of origin, directly from plasma. By simultaneously tracking multiple somatic mutations in ctDNA, our approach outperformed immunoglobulin sequencing and radiographic imaging for the detection of minimal residual disease and facilitated noninvasive identification of emergent resistance mutations to targeted therapies. In addition, we identified distinct patterns of clonal evolution distinguishing indolent follicular lymphomas from those that transformed into DLBCL, allowing for potential noninvasive prediction of histological transformation. Collectively, our results demonstrate that ctDNA analysis reveals biological factors that underlie lymphoma clinical outcomes and could facilitate individualized therapy.

Death After Colectomy: It's Later Than We Think

BACKGROUND Clinical outcomes are increasingly subject to objective assessment and professional accountability. Informed consent relies on accurate estimation of operative risk. Current scoring systems for assessment of operative mortality after colorectal surgery (CRS) almost uniformly report 30-day mortality and may not represent true risk. DESIGN Prospective cohort. SETTING University-affiliated Veterans Affairs Medical Center. PATIENTS All patients who underwent resections of the colon and/or rectum (as the principal operation) at a single hospital whose data are captured in the Veterans Affairs National Surgical Quality Improvement Program (VA-NSQIP) database from January 1, 2000, through December 31, 2006. MAIN OUTCOME MEASURES Mortality at 30 days and 90 days. RESULTS The VA-NSQIP cohort included 186 patients who underwent CRS, including 148 patients who underwent elective procedures (79.6%) and 38 patients who underwent emergency procedures (20.4%). All but 8 patients were men, with a median age of 67 years (range, 26-92 years). Laparoscopic operations comprised 24.2% and open operations comprised 75.8%. Most (60.8%) were performed for neoplasms. The actual 30-day mortality rates (all, elective, and emergency procedures) were 4.3%, 1.4%, and 15.8%, respectively. These rates closely mirrored the calculated VA-NSQIP risk-adjusted observed-to-expected ratio for 30-day mortality (4.8%, 1.8%, and 18.2%, respectively). However, mortality at 90 days increased substantially to 9.1%, 4.1%, and 28.9%, respectively. CONCLUSION The 30-day mortality significantly underreports the true risk of death after CRS. The 90-day mortality rate should be included as a standard outcome measure after CRS because it serves as a better estimation of risk for counseling patients.

Comparison of intensity-modulated radiotherapy and 3-dimensional conformal radiotherapy as adjuvant therapy for gastric cancer†

The current study was performed to compare the clinical outcomes and toxicity in patients treated with postoperative chemoradiotherapy for gastric cancer using intensity‐modulated radiotherapy (IMRT) versus 3‐dimensional conformal radiotherapy (3D CRT).

Lymph Nodes and Survival in Pancreatic Neuroendocrine Tumors

HYPOTHESIS Lymph node metastases decrease survival in patients with pancreatic neuroendocrine tumors (pNETs). DESIGN Prospective database searches. SETTING National Institutes of Health (NIH) and Stanford University Hospital (SUH). PATIENTS A total of 326 patients underwent surgical exploration for pNETs at the NIH (n = 216) and SUH (n = 110). MAIN OUTCOME MEASURES Overall survival, disease-related survival, and time to development of liver metastases. RESULTS Forty patients (12.3%) underwent enucleation and 305 (93.6%) underwent resection. Of the patients who underwent resection, 117 (35.9%) had partial pancreatectomy and 30 (9.2%) had a Whipple procedure. Forty-one patients also had liver resections, 21 had wedge resections, and 20 had lobectomies. Mean follow-up was 8.1 years (range, 0.3-28.6 years). The 10-year overall survival for patients with no metastases or lymph node metastases only was similar at 80%. As expected, patients with liver metastases had a significantly decreased 10-year survival of 30% (P < .001). The time to development of liver metastases was significantly reduced for patients with lymph node metastases alone compared with those with none (P < .001). For the NIH cohort with longer follow-up, disease-related survival was significantly different for those patients with no metastases, lymph node metastases alone, and liver metastases (P < .001). Extent of lymph node involvement in this subgroup showed that disease-related survival decreased as a function of the number of lymph nodes involved (P = .004). CONCLUSIONS As expected, liver metastases decrease survival of patients with pNETs. Patients with lymph node metastases alone have a shorter time to the development of liver metastases that is dependent on the number of lymph nodes involved. With sufficient long-term follow-up, lymph node metastases decrease disease-related survival. Careful evaluation of number and extent of lymph node involvement is warranted in all surgical procedures for pNETs.