Neoadjuvant therapy for adenocarcinoma of the rectum: tumor response and acute toxicity.

PURPOSE: This study was designed to evaluate the down-staging effect and acute toxicity of preoperative radiation and chemoradiation for primary adenocarcinoma of the rectum. METHODS: The results of pretreatment staging with transrectal ultrasound and computed tomography were compared with final histologic stage in 260 consecutive patients who underwent neoadjuvant therapy and proctectomy for primary adenocarcinoma of the rectum. Patients underwent short-course radiation (2,000 cGy in five fractions), long-course radiation (4,500 cGy in 25 fractions), or chemoradiation (4,500 cGy in 25 fractions with concurrent chemotherapy). RESULTS: Down-staging of one or more T stages occurred in 116 of 260 (45 percent) patients overall (short-course radiation 34/82 (42 percent), long-course radiation 55/122 (45 percent), chemoradiation 27/56 (48 percent), P = not significant). Down-staging of one or more N stages occurred in 85 of 178 (48 percent) patients overall (short-course radiation 12/45 (27 percent), long-course radiation 49/86 (57 percent), chemoradiation 24/47 (51 percent), P = 0.003). Complete pathologic response was observed in 16 of 260 (6 percent) patients overall (short-course radiation 4/82 (5 percent), long-course radiation 5/122 (4 percent), chemoradiation 7/56 (13 percent), P = 0.08). Resection with negative margins (distal, proximal, and radial) was achieved in 211 of 227 patients (93 percent) in whom complete radial margin data were available. Permanent stomas were created in 35 percent of patients; temporary stomas were created in 15 percent. Thirty-three Grade 3 or 4 toxicities occurred in 22 of 260 (8 percent) patients overall during neoadjuvant therapy. Toxicity was more frequent in patients receiving chemoradiation (14/56; 25 percent) and long-course radiation (8/122; 7 percent) than in those receiving short-course radiation (0/82; 0 percent), P < 0.0001. Perioperative complications occurred in 93 patients overall (36 percent). The postoperative mortality rate was 0.4 percent (1/260). There was no significant difference in the complication rate between patients treated with short-course radiation (26/82; 32 percent), long-course radiation (46/122; 36 percent), and chemoradiation (21/56; 38 percent). CONCLUSION: Neoadjuvant therapy for adenocarcinoma of the rectum is well tolerated and can produce substantial down-staging and a high curative resection rate. Chemoradiation can achieve high complete pathologic response rates, although toxicity during neoadjuvant therapy is greater than for radiation alone. Short-course radiation can achieve down-staging of both T stage and N stage.

Lymphoscintigraphic technique to image canine esophageal lymph nodes.

Current noninvasive methods of imaging esophageal lymph nodes have an accuracy, specificity, and sensitivity of 70%. Using a flexible esophagoscope, technetium-99m antimony sulfide colloid was injected in the esophageal submucosa of six dogs who then underwent nuclear scans to identify lymph-node location. The euthanized animals underwent dissection of cervical, thoracic, and abdominal lymph nodes. Student's t-test showed no statistical difference in the number of lymph nodes visualized in the neck (3.5 +/- 0.6), parietal thorax (1.2 +/- 0.4), visceral thorax (2.2 +/- 0.7), and abdomen (1.0 +/- 0.0) on premorbid nuclear scans and in the number of radiolabeled lymph nodes found in the neck (3.2 +/- 0.9), parietal thorax (1.2 +/- 0.2), visceral thorax (1.8 +/- 1.0), and abdomen (1.2 +/- 0.2) on dissection of the carcass. The positions of the lymph nodes based on the premorbid nuclear scans matched the locations of the radiolabeled lymph nodes at dissection. Dissected tissue was pathologically confirmed as lymph node. The position and number of lymph nodes in the cervical, intrathoracic, and abdominal regions on nuclear scan correlated with the position and number of lymph nodes found on anatomic dissection. This technique may have a higher sensitivity and specificity than current noninvasive techniques in the staging of esophageal lymphatic metastasis.

Management of diagnostic dilemmas of the pancreas by ultrasonographically guided laparoscopic biopsy.

INTRODUCTION: Pancreatic lesions may be difficult to diagnose because of small size or inaccessibility. Such lesions are being seen with increasing frequency because of advances in pancreatic imaging techniques. In the past 18 months we have evaluated 14 patients whose pancreatic lesions could not be diagnosed by traditional means, including percutaneous biopsy. METHODS: With the patient under general anesthesia, the anterior surface of the pancreas was exposed by a three-trocar laparoscopic technique. The lesion was located by laparoscopic ultrasonography. A core biopsy needle was inserted into the lesion under simultaneous visual and ultrasonographic guidance using picture-in-picture techniques. RESULTS: The main diagnostic dilemma encountered was the differentiation of pancreatic cancer from pancreatitis. Other conditions were lymphoma and renal cell carcinoma. Excellent tissue samples were obtained, allowing diagnosis and planning of treatment in all cases. Operative time ranged from 1 to 4 hours, and length of stay ranged from 1 to 3 days. Blood transfusions were not required, and there were no complications. Alcohol nerve block was performed laparoscopically in one patient in this group after the diagnosis was made by frozen section. CONCLUSIONS: Direct ultrasonographically guided laparoscopic biopsy provides rapid, safe diagnosis of pancreatic lesions.

Results of a technique of pancreaticojejunostomy that optimizes blood supply to the pancreas.

BACKGROUND: Anastomotic failure after pancreaticojejunostomy is still a common problem. Failure rates have not decreased perceptibly in the past 3 decades. The neck of the pancreas is a vascular watershed between celiac and superior mesenteric arterial systems. Prior attempts to reduce anastomotic failure at pancreaticojejunostomy have not focused on issues related to blood supply of the pancreas. The aim of this study was to determine whether pancreaticojejunostomy performed using a technique that included optimization of blood supply to the pancreas, would result in a low anastomotic failure rate. METHODS: The technique was prospectively evaluated in 40 patients having pancreaticojejunostomy, 39 during pancreaticoduodenectomy and 1 after traumatic transection of the neck of the pancreas. Blood supply to the pancreatic neck was evaluated clinically and by Doppler techniques. When blood supply was considered marginal, the pancreas was re-resected 1.5-2.0 cm to the left, away from the vascular watershed. RESULTS: Blood supply at the cut margin of pancreas was judged as brisk in 24 patients and marginal in 16 patients. Resecting a segment of pancreas in these 16 patients resulted in brisk bleeding from the new cut margin in all but 1 patient who had an anomalous artery that had to be sacrificed for oncologic reasons. The only fistula in the series occurred in this patient. There were no intraabdominal abscesses. CONCLUSIONS: A technique that includes ensuring adequate blood supply to the pancreas can result in a very low rate of anastomotic failure.

Epithelial cell growth and differentiation. III. Promoting diversity in the intestine: conversations between the microflora, epithelium, and diffuse GALT.

Homeostasis in the self-renewing mouse intestinal epithelium appears to be regulated in large part by cell nonautonomous mechanisms. The society of nonpathogenic bacteria that resides in the intestine is an important source of instructions that modify epithelial differentiation programs. The stability of this society is remarkable given its numerical, compositional, and spatial complexity, the openness of the ecosystem, and the fact that the epithelium is replaced so rapidly. The ability of components of this society to influence epithelial differentiation may represent a critical step in allowing specific groups of organisms to be assembled in specific regions of the gut. Simplified model systems have been created to define and dissect the conversations between microbe and host. These systems use inbred strains of mice that are raised under germ-free conditions and then monocontaminated with a single component of the microflora. The results suggest that a trialogue involving communications between the microflora, the epithelium, and the diffuse gut-associated lymphoid tissue (GALT) may play a key role in establishing and maintaining the spatial diversity of this remarkable ecosystem.

Examining the role of Paneth cells in the small intestine by lineage ablation in transgenic mice.

The Paneth cell lineage is one of four epithelial lineages derived from the adult mouse small intestine's multipotent stem cell. Mature Paneth cells secrete antimicrobial peptides (cryptdins), growth factors, as well as two gene products, a secreted phospholipase A2 and matrilysin, that has been implicated as modifiers of adenoma formation in mice containing a mutation in the tumor suppressor Apc. Immature Paneth cells are located just above and below the cell layer, in intestinal crypts, that has been proposed to contain the multipotent stem cell. Paneth cells differentiate during a downward migration to the crypt base. The location and direction of Paneth cell migration, their high density and long residency time at the crypt base, and the nature of their secreted gene products, suggest that they may influence the structure and/or function of the stem cell niche. Paneth cell ablation can therefore be viewed as an experimental manipulation of the cellular microenvironment that purportedly contains the stem cell and its immediate descendants. Two types of ablation experiments were performed in transgenic mice. Nucleotides -6500 to +34 of the mouse cryptdin-2 gene (CR2) were used to express an attenuated diphtheria toxin A fragment. Light and electron microscopic immunohistochemical analyses of several pedigrees of postnatal day 28 to 180 animals established that ablation of Paneth cells is accompanied by an increase in the proportion of undifferentiated crypt base columnar cells. These cells normally co-exist with Paneth cells. The ablation does not produce a detectable effect on the proliferation or terminal differentiation programs of the other three lineages or on host-microbial interactions. The last conclusion is based on the ability of crypts to remain free of microbes detectable by Gram and Warthin-Starry stains and by retention of the normal crypt-villus distribution of components of the diffuse gut-associated lymphoid tissue. CR2-directed expression of simian virus 40 large T antigen also results in a loss of mature Paneth cells but produces a marked amplification of crypt cells having a morphology intermediate between Paneth and granule goblet cells. EM immunohistochemical analyses suggest that intermediate cells can differentiate to mature goblet cells but not to Paneth cells, as they migrate up the crypt-villus axis. Our findings suggest that (i) stemness in the crypt is not defined by instructive interactions involving the Paneth cell; (ii) expressing a Paneth cell fate may require that precursors migrate to the crypt base; (iii) antimicrobial factors produced by Paneth cells are not required to prevent colonization of small intestinal crypts; and (iv) this lineage does not function to maintain the asymmetric crypt-villus distribution of components of the diffuse gut-associated lymphoid tissue.

Bi-transgenic mice reveal that K-rasVal12 augments a p53-independent apoptosis when small intestinal villus enterocytes reenter the cell cycle.

Studies in cell culture systems have indicated that oncogenic forms of Ras can affect apoptosis. Activating mutations of Ras occur in approximately 30% of all human tumors and 50% of colorectal carcinomas. Since these mutations appear at early or intermediate stages in multistep journeys to neoplasia, an effect on apoptosis may help determine whether initiated cells progress towards a more neoplastic state. We have tested the effects of K-rasVal12 on apoptosis in transgenic mice. A lineage-specific promoter was used to direct expression of human K-rasVal12, with or without wild-type (wt) or mutant SV-40 T antigens (TAg), in postmitotic villus enterocytes, the principal cell type of the small intestinal epithelium. Enterocytes can be induced to reenter the cell cycle by TAgWt. Reentry is dependent upon the ability of TAg to bind pRB and is associated with a p53-independent apoptosis. Analyses of K-rasVal12 x TAgWt bi-transgenic animals indicated that K-rasVal12 can enhance this apoptosis threefold but only in cycling cells; increased apoptosis does not occur when K-rasVal12 is expressed alone or with a TAg containing Glu107,108two head right arrow Lys107, 108 substitutions that block its ability to bind pRB. Analysis of bi-transgenic K-rasVal12 x TAgWt mice homozygous for wild-type or null p53 alleles established that the enhancement of apoptosis occurs through a p53-independent mechanism, is not attributable to augmented proliferation or to an increase in abortive cell cycle reentry (compared to TAgWt mice), and is not associated with detectable changes in the crypt-villus patterns of expression of apoptotic regulators (Bcl-2, Bcl-xL, Bak, and Bax) or mediators of epithelial cell-matrix interactions and survival (e.g., alpha5beta1 integrin and its ligand, fibronectin). Coexpression of K-rasVal12 and TAgWt produces dysplasia. The K-rasVal12-augmented apoptosis is unrelated to this dysplasia; enhanced apoptosis is also observed in cycling nondysplastic enterocytes that produce K-rasVal12 and a TAg with a COOH-terminal truncation. The dysplastic epithelium of K-rasVal12 x TAgWt mice does not develop neoplasms. Our results are consistent with this finding: (a) When expressed in initiated enterocytes with a proliferative abnormality, K-rasVal12 facilitates progression to a dysplastic phenotype; (b) by diminishing cell survival on the villus, the oncoprotein may impede further progression; and (c) additional mutations may be needed to suppress this proapoptotic response to K-rasVal12.