Photodissociation and Infrared Spectroscopy of Uranium-Nitrogen Cation Complexes.

Laser vaporization of uranium in a pulsed supersonic expansion of nitrogen is used to produce complexes of the form U+(N2)n (n = 1-8). These ions are mass selected in a reflectron time-of-flight spectrometer and studied with visible and UV laser fixed-frequency photodissociation and with tunable infrared laser photodissociation spectroscopy. The dissociation patterns and spectroscopy of U+(N2)n indicate that N2 ligands are intact molecules and that there is no insertion chemistry resulting in UN+ or NUN+. Fixed frequency photodissociation at 532 and 355 nm indicate that the U+-N2 bond dissociation energy varies little with changing coordination. The photon energy and the number of ligands eliminated allow an estimate of the average U+-N2 dissociation energy of 12 kcal/mol. Infrared bands are observed for these complexes near the N-N stretch vibration via elimination of N2 molecules. These resonances are observed to be shifted about 130 cm-1 to the red from the free-N2 frequency for complexes with n = 3-8. Density functional theory indicates that U+ is most stable in the sextet state in these complexes and that N2 molecules bind in end-on configurations. The fully coordinated complex is predicted to be U+(N2)8, which has a cubic structure. The vibrational frequencies predicted by theory are consistently lower than those in the experiment, independent of the isomeric structure or spin state of the complexes. Despite its failure to reproduce the infrared spectra, theory provides an average U+-N2 dissociation energy of 11.8 ± 0.5 kcal/mol, in good agreement with the value from the experiments.

SP rTaTME: initial clinical experience with single-port robotic transanal total mesorectal excision (SP rTaTME).

BACKGROUND: The technical difficulty and steep learning curve of transanal total mesorectal excision (taTME) has limited widespread adoption. The single-port (SP) daVinci robot is designed to facilitate single-incision and natural-orifice transluminal endoscopic surgery (NOTES). This paper describes the first clinical experience of single-port robotic taTME (SP rTaTME). METHODS: This was a prospective study on consecutive patients with rectal cancer who underwent SP rTaTME proctosigmoidectomy with handsewn coloanal anastomosis in December 2018 and January 2019. The primary outcome was technical feasibility of the procedure. The secondary outcomes include blood loss, intraoperative complications, length of hospital stay, quality of the TME specimen, short- and long-term morbidity and mortality, as well as short-term oncologic follow -up. RESULTS: There were two patients, a 48-year-old male and a 38-year-old female. Both operations were completed successfully without complications or conversion. Estimated blood loss was 200 mL and 130 mL. In both cases the TME was completed transanally using the SP robot. In the first patient, the abdominal portion was completed through an abdominal single-incision; in the second patient the operation was entirely performed transanally as a pure NOTES procedure. In both cases, the final pathology report showed a complete TME with negative margins. Patients were discharged on postoperative day 3 and 4,respectively. There was no long-term morbidity or mortality. CONCLUSIONS: SP rTaTME is feasible and can be safely performed. It provides excellent optics and dexterity to work in a limited space. Future studies are required to further define the safety profile and the ultimate utility of the SP robot for taTME.

First clinical experience with single-port robotic transanal minimally invasive surgery (SP rTAMIS) for benign rectal neoplasms.

BACKGROUND: The new da Vinci Single-Port (SP) robot is a single-arm four-channel robotic system well suited for endoluminal surgery. We report our initial experience performing SP robotic transanal minimally invasive surgery (SP rTAMIS) for rectal neoplasms. METHODS: Under Institutional Review Board approval, two patients with rectal neoplasms were prospectively enrolled for elective SP rTAMIS. The primary endpoint was to report the safety and feasibility of successful procedure completion with the SP robot. Secondary endpoints included patient characteristics and perioperative metrics. RESULTS: Both patients underwent successful SP rTAMIS resection of rectal neoplasms without intraoperative complications or conversions. The lesions were 4.0 cm and 3.0 cm in size, located 6 cm and 7 cm cephalad to the anorectal ring. Excisions were full thickness with no piecemeal extractions or specimen fragmentation. Estimated blood loss was 0 mL and 30 mL. The mean excised area was 13.4 cm2 (22.7 cm2 and 9.0 cm2). The mean docking time was 5.25 min (range 2-8 min) and mean console time was 122.5 min (98 min and 147 min). Patients tolerated a liquid diet on postoperative day (POD) 0 and were discharged on POD 1 after tolerating a low residue diet and having bowel function. Pathology showed two adenomas with negative margins. There was no immediate or delayed morbidity or mortality. CONCLUSIONS: Our initial experience indicates that SP rTAMIS is a safe and feasible approach for local excision of rectal lesions. While SP rTAMIS is very promising, more experience with this approach is necessary to determine its widespread applicability.

Infrared spectroscopy and anharmonic theory of H3 +Ar2,3 complexes: The role of symmetry in solvation.

The vibrational spectra of H3 +Ar2,3 and D3 +Ar2,3 are investigated in the 2000 cm-1 to 4500 cm-1 region through a combination of mass-selected infrared laser photodissociation spectroscopy and computational work including the effects of anharmonicity. In the reduced symmetry of the di-argon complex, vibrational activity is detected in the regions of both the symmetric and antisymmetric hydrogen stretching modes of H3 +. The tri-argon complex restores the D3h symmetry of the H3 + ion, with a concomitant reduction in the vibrational activity that is limited to the region of the antisymmetric stretch. Throughout these spectra, additional bands are detected beyond those predicted with harmonic vibrational theory. Anharmonic theory is able to reproduce some of the additional bands, with varying degrees of success.

rSILS: initial clinical experience with single-port robotic (SPr) right colectomy.

BACKGROUND: The da Vinci Single-Port (SP) robot is a novel platform designed to facilitate single-incision robotic surgery (rSILS). The objective of this study was to describe our initial experience using this platform for SP robotic (SPr) right colectomy. METHODS: Under a Food and Drug Administration-regulated feasibility study and Institutional Review Board approval, a patient with cecal adenocarcinoma underwent an SPr right colectomy. The primary endpoint was the safety and feasibility of the first SPr right colectomy performed in the USA. Secondary endpoints included perioperative metrics, morbidity and mortality. RESULTS: An SPr Standard right colectomy was performed through a 4-cm single incision without the need for conversion or additional port placement. Estimated blood loss was 100 mL and there were no intraoperative complications. The robot was docked once with a docking time of 19 min. Total console time was 116 min and operative time was 219 min. The patient tolerated clear liquids on postoperative day (POD) 0 and a low-residue diet on POD 1. The patient had flatus and a bowel movement on POD 1. She was discharged home on POD 3. Final pathology showed pT3N0 cecal adenocarcinoma with negative margins and 0/24 lymph nodes positive for disease. CONCLUSIONS: Our initial experience demonstrates that an SPr right colectomy is feasible and can be safely completed. We completed an oncologic resection of a cecal adenocarcinoma without complications. The SP robot facilitates the utilization of robotic technology in a single-incision platform to perform colorectal procedures and offers promising benefits in the advancement of robotic surgery.

Single-port robotic left colectomy: first clinical experience using the SP robot (rSILS).

BACKGROUND: The single-port daVinci robot is a new platform designed to facilitate single-incision surgeries. The objective of this study was to describe the first clinical experience in colorectal surgery using a novel single-port robotic system and report its feasibility and safety. METHODS: After Institutional Review Board approval was obtained and the study was registered with ClinicalTrials.gov, we performed single port robot-assisted left colectomy using the novel daVinci SP surgical system on two patients. The surgeries were completed through a single incision. The multichannel port accommodates a three-dimensional articulating camera and three double-jointed articulating instruments. The primary aim of this study was to report, for the first time in the USA, the technical feasibility of the procedure in the living human. The secondary aim was to report the outcomes including blood loss, number of incisions, number of dockings, docking time of the robot, incision length, operative time, console time, need for additional port and instrumentation, intraoperative complications, morbidity and mortality, time for tolerating diet, bowel function, and discharge. RESULTS: Both surgeries were completed without conversion through a single incision, 4.0 and 4.5 cm in size. Estimated blood loss was less than 60 ml in both cases. The robot was docked two and three times. Mean time to dock was 13 min (range 3-33 min). There were no intraoperative complications, no morbidity or death. Discharges occurred on postoperative days 2 and 3. CONCLUSIONS: Single-port robotic colectomy using the new robot is feasible and can be safely completed. The overall utility and functionality of the SP robot portends wide utilization and expansion of this technique. Careful development and analysis of the procedure outcomes, training, and cost will be necessary to properly advance the field.

Photodissociation of Manganese Oxide Cluster Cations.

Manganese oxide cluster cations are produced by laser vaporization in a pulsed nozzle source and detected with time-of-flight mass spectrometry. The mass spectrum contains intense peaks for stoichiometries corresponding to (MnO) n+. Multiphoton photodissociation of these clusters yields smaller ions with the same stoichiometric ratio, either by sequential elimination of MnO units or by various fission processes with roughly equal efficiencies. Fragmentation of clusters containing excess oxygen also yields (MnO) n+ fragments. These apparently stable fragments are investigated further using density functional theory to determine their likely structures. The lowest energy structure for Mn2O2+ is found to be a planar ring, and those for Mn4O4+ and Mn6O6+ are cuboids. Mn3O3+ is predicted to have a six-membered ring structure and Mn5O5+ has a fused cube/ring configuration similar to the structure of the oxygen evolving center of Photosystem II. Open-shell, high-spin configurations on individual manganese atoms couple antiferromagnetically and ferromagnetically to produce low-spin and high-spin configurations on different sized clusters.

Full-thickness neorectal prolapse after transanal transabdominal proctosigmoidectomy for low rectal cancer: a cohort study.

AIM: Transanal transabdominal proctosigmoidectomy (TATA) with a coloanal anastomosis is an alternative to abdominoperineal excision of the rectum (APR) for low rectal cancer. Neorectal prolapse is an unusual complication following TATA. This study aimed to determine the incidence of neorectal prolapse after TATA for low rectal cancer. METHOD: This cohort study was conducted in a tertiary referral colorectal centre. From a prospectively maintained database including 1093 patients treated for rectal cancer between 1984 and 2016 we identified those who underwent sphincter-preserving surgery. Data regarding the incidence, management and outcomes of neorectal prolapse were analysed. RESULTS: A total of 409 patients were identified, of whom 185 underwent open surgery and 224 a minimally invasive surgical procedure (MIS). All received neoadjuvant chemoradiation. Neorectal prolapse occurred in 4.6% (n = 19) with an incidence of 2.2% in the open and 6.7% in the MIS group (P = 0.023), with no difference between MIS techniques. There was one recurrence of neorectal prolapse (5.9%). The incidence of neorectal prolapse was higher in women (9.5%) than men (2.5%) (P = 0.011). There were no differences in local recurrence rates between the neorectal prolapse group (5.3%) and our population without prolapse (3.4%) (P = 0.79). CONCLUSION: Neorectal prolapse is a rare occurrence following minimally invasive sphincter-saving surgical procedures performed for rectal cancer. It appears to be more frequent in patients who undergo MIS procedures and in women.

Communication: Trapping a proton in argon: Spectroscopy and theory of the proton-bound argon dimer and its solvation.

Ion-molecule complexes of the form H+Arn are produced in pulsed-discharge supersonic expansions containing hydrogen and argon. These ions are analyzed and mass-selected in a reflectron spectrometer and studied with infrared laser photodissociation spectroscopy. Infrared spectra for the n = 3-7 complexes are characterized by a series of strong bands in the 900-2200 cm-1 region. Computational studies at the MP2/aug-cc-pVTZ level examine the structures, binding energies, and infrared spectra for these systems. The core ion responsible for the infrared bands is the proton-bound argon dimer, Ar-H+-Ar, which is progressively solvated by the excess argon. Anharmonic vibrational theory is able to reproduce the vibrational structure, identifying it as arising from the asymmetric proton stretch in combination with multiple quanta of the symmetric argon stretch. Successive addition of argon shifts the proton vibration to lower frequencies, as the charge is delocalized over more ligands. The Ar-H+-Ar core ion has a first solvation sphere of five argons.

Transanal TATA/TME: a case-matched study of taTME versus laparoscopic TME surgery for rectal cancer.

BACKGROUND: Natural orifice translumenal endoscopic surgery (NOTES) has always made more sense in the colorectal field where the target organ for entry houses the pathology. To address the question whether an adequate total mesorectal excision (TME) for rectal cancer can be performed from a transanal bottoms-up approach, we performed a case-matched study. METHODS: Starting in 2009, transanal TME (taTME) surgery was selectively used for rectal cancer after neoadjuvant therapy and prospectively entered into a database. Between March 2012 and February 2014, 17 consecutive taTME rectal cancer patients were identified and case-matched to multiport laparoscopic TME (MP TME) based on age, body mass index, uT stage, radiation dose, level in the rectum, and procedure. Perioperative outcomes, morbidity, mortality, local recurrence, completeness of TME, and radial and distal margins were analyzed. Statistically significant differences were identified using Student's t test. RESULTS: There were 12 transanal abdominal transanal (TATA)/5 abdominoperineal resection procedures in each group. Data regarding overall/taTME/MP TME are as follows: % positive-circumferential margin: 2.9/0/5.9 % (p = 0.32). Distal margin: 0/0/0 %. Complete or near-complete TME: 97.1/100/94.1 % (p = 0.32). Incomplete TME 2.9/0/5.9 % (p = 0.32). Local recurrence: 2.9/5.9/0 % (p = 0.32). There were no perioperative mortalities. Morbidity in each group: 26.4/23.5/29.4 % (p = 0.79). There were no differences in perioperative or postoperative outcomes except days to clear liquids (1/2 days, p = 0.03) and largest incision length (1.3/2.6 cm, p = 0.05). CONCLUSIONS: We demonstrated no differences in perioperative/postoperative outcomes or pathologic TME outcomes of transanal or bottoms-up TME compared to standard laparoscopic TME. TaTME is a promising progressive approach to NOTES and deserves additional evaluation.

Minimally invasive colorectal surgery.

Adoption of laparoscopic colorectal surgery has been slow. In the United States, of approximately 250,000 colectomies each year, only 5% to 15% of these cases are being done laparoscopically. Laparoscopic colorectal surgery can be performed successfully on patients for both benign and malignant conditions in any anatomic location of the colon and rectum. The COST trial definitively established that laparoscopic colon surgery for cancer had similar rates of local recurrence and survival compared to open surgery, with better short-term outcomes. It demonstrated that laparoscopic resections resulted in shorter hospital stays, decreased IV narcotics and oral analgesics, and improved quality of life within two weeks of surgery. In the authors' clinical experience of more than 1500 laparoscopic surgeries, patients who undergo laparoscopic colorectal surgery experience decreased rates of wound infection, hernia, and bowel obstruction. One of the challenges of laparoscopic colorectal surgery is standardizing these complex, minimally invasive procedures in the operating room. With standard techniques, one can create optimal outcomes for patients, minimizing perioperative complications and maximizing oncologic results. This paper describes a sequenced step approach for each procedure to facilitate this. Left colectomy follows a nine-step process, and right colectomy follows a four-step process. Both of these procedures are described in detail. The newest horizon in minimally invasive surgery is single incision surgery, which allows for colorectal resections through a single 2.5 cm incision, producing an excellent cosmetic result. Based on this chapter, we advocate the laparoscopic approach be used as the primary method for colorectal surgery.

Fewer than 12 lymph nodes can be expected in a surgical specimen after high-dose chemoradiation therapy for rectal cancer.

PURPOSE: Lymph node harvest of >or=12 has been adopted as a marker for adequacy of resection for colorectal cancer. We have noted a paucity of lymph nodes in rectal cancer specimens after neoadjuvant therapy, positing that the number of lymph nodes depends on the response to radiation and may not be an appropriate benchmark. Our purpose was to determine whether the number of lymph nodes harvested after neoadjuvant therapy is a useful quality indicator. METHODS: A database of rectal cancer patients was queried to identify patients undergoing total mesorectal excision after neoadjuvant chemoradiation between January 1997 and August 2007. We compared patients with <12 lymph nodes to those with >or=12 lymph nodes relative to multiple patient and treatment factors. RESULTS: One hundred seventy-six patients were identified (119 men; mean age, 60.4 y (range, 22-87)). Mean lymph node harvest was 10.1 (range, 1-38). Only 28% had >or=12 lymph nodes and 32% had <6 lymph nodes. There was no statistically significant difference in lymph node harvest relative to radiation dosage, age, tumor response, or type of surgery. There was no correlation between the number of lymph nodes harvested and the number of nodes positive for cancer. CONCLUSIONS: With a standardized surgical technique and pathologic evaluation, the number of lymph nodes present after neoadjuvant chemoradiation and total mesorectal excision for rectal cancer varies greatly.

Transanal endoscopic microsurgery in the treatment of select rectal cancers or tumors suspicious for cancer.

BACKGROUND: This study describes a personal experience with the use of transanal endoscopic microsurgery to facilitate surgical access, and to determine the ability of this technique to reduce the need for major abdominal procedure and prevent the need for a temporary or permanent colostomy in select patients with known or suspected rectal cancer. METHODS: The subjects of this study were 43 patients with rectal cancer or tumors who had a high likelihood of malignancy. The 24 men and 19 women comprised two groups: patients with known cancer ( n = 16) and patients with tumors suspicious for cancer ( n = 27), six of whom proved to have invasive malignancy. The tumors ranged in size from 1 to 7 cm (average, 3.5 cm). The tumor's inferior level in the rectum ranged from -1 to 21 cm (average, 6.5 cm). Eleven patients known to have rectal cancer were treated with preoperative radiation or chemoradiation. By ordinary standards, 22 patients would have received an abdominal perineal resection; 14 patients would have qualified for abdominal sphincter-preserving operations; and 7 patients were indeterminate. Full-thickness local excisions were disk excisions ( n = 23), hemicircumferential excisions ( n = 19), and sleeve resection ( n = 1). The ages of the patients ranged from 30 to 91 years (average, 66.7 years). RESULTS: In this study, 90% avoided a major abdominal operation (39/43), and 90% avoided an abdominal perineal resection of the patients (20/22). The complications were as follows: mortality ( n = 10), morbidity ( n = 9), minor wound separation ( n = 6), and major wound separation ( n = 3). Two of these complications were rectovaginal fistulas: the one in a 91-year-old patient who presented with a fistula and the other in a 77-year-old patient who presented with a previously irradiated and incompletely excised cancer. A single instance of locally recurrent cancer required an abdominal perineal resection. There were no other recurrences. Overall, three patients required a stoma (7%). CONCLUSION: Transanal endoscopic microsurgery promises to offer a safe and effective option for the selective treatment of patients with rectal cancer after preoperative chemoirradiation, and for the management of tumors suspicious for rectal cancer. Transanal endoscopic microsurgery used selectively can reduce the need for major abdominal surgery and colostomy.

Evaluating and monitoring the adolescent with pulmonary function testing.

This article reviews pulmonary function tests (quantitative measurements of physiologic functioning of lungs, chest wall, and respiratory muscles) as valuable tools for the diagnosis and management of chronic respiratory disease in adolescents. Advances in technology have made pulmonary function testing more available and, for some tests, easier to perform. Pulmonary function evaluation is used for diagnosis of pulmonary disease. Testing will identify abnormal physiologic processes that result in obstructive or restrictive pulmonary disease and, together with a complete history, physical examination, and other tests, help to determine the specific etiology. Pulmonary function measurement may be used to manage a patientís disease over time. Quantitative evaluation of the response to many specific therapies, such as asthma medications and environmental control, can only be achieved by measuring pulmonary function. Monitoring pulmonary toxicity of medications, such as chemotherapeutic agents, is also done by measuring pulmonary function. In many patients with chronic pulmonary disease, such as cystic fibrosis, the pulmonary function laboratory can be used to assess the patient's physiologic limitation.

Effects of chronic tobramycin treatment on distortion product otoacoustic emissions.

OBJECTIVE: To investigate the effects of chronic tobramycin treatment on distortion product otoacoustic emission (DPOAE) latencies and response growth detection thresholds in human subjects to determine the sensitivity of these DPOAE features to ototoxic damage. DESIGN: Six groups of children in two different age ranges were tested: three groups in the 7 to 14 yr age range, i.e., six children with normal hearing, four cystic fibrosis (CF) patients who received no aminoglycosides, and eight CF patients who received low- to moderate-cumulative doses of tobramycin (< 1250 mg/kg) for respiratory infections; and three groups of five subjects each in the 15 to 23 yr age range, i.e., the healthy group and the CF groups that received low- (< 285 mg/kg) and moderate-(1000 to 2000 mg/kg) cumulative drug dosages. The aggregate drug dosages compiled longitudinally over the past 5 yr were used to group the drug-treated CF patients. All subjects showed normal audiometric profiles (< or = 25 dB HL in the conventional frequency region and age-appropriate thresholds as described by Osterhammel and Osterhammel [1979] in the high-frequency region) and DP-grams (absolute DPOAE and noise amplitudes being consistent with the normative data obtained with the CUBeDIS system at this institution). RESULTS: Even though the audiometric profiles and DP-grams of all drug-treated CF groups were identical to their healthy counterparts, the DPOAE latencies and growth function thresholds showed significant changes. Whereas low and low-to-moderate doses of tobramycin were related to DPOAE latency prolongations, higher cumulative drug doses of 1000 to 2000 mg/kg produced significant reductions in DPOAE latencies. Response growth detection thresholds at high frequencies showed significant elevations in all CF patient groups treated with tobramycin, regardless of drug dosages, as compared with the control subjects. CONCLUSIONS: DPOAE amplitudes may not reflect the earliest changes produced by chronic aminoglycoside treatment, suggesting that cochlear ototoxicity may be more effectively monitored through the assessment of latencies and response growth detection thresholds. These findings pertain at least to the early stages of ototoxicity development, specifically during chronic tobramycin treatment. In light of the small sample size, however, these outcomes must be considered as tentative.

Comparison of the flutter device to standard chest physiotherapy in hospitalized patients with cystic fibrosis: a pilot study.

STUDY OBJECTIVE: A preliminary study comparing the efficacy and safety of the flutter device (Flutter) to standard, manual chest physiotherapy (CPT) in hospitalized cystic fibrosis (CF) patients undergoing an acute pulmonary exacerbation. DESIGN: Open label, comparative trial with alternate assignment. SETTING: Community and childrens' hospital acute-care wards. PARTICIPANTS: Twenty-two CF patients (ages 8 to 44 years) undergoing a total of 33 hospitalizations for acute pulmonary exacerbation. INTERVENTIONS: Complete pulmonary function tests (PFTs) were done at baseline (admission), weekly, and upon discharge from the hospital. Clinical score (CS) was determined at the time of hospital admission and at discharge. Participants were assigned to receive supervised Flutter therapy or standard, manual CPT four times per day during the hospitalization. Patients were monitored for complications, including hemoptysis, hypoxemia, and pneumothorax. RESULTS: The groups (CPT and Flutter) did not differ at baseline in demographics or Shwachman score, nor was length of hospitalization different. Significant improvements were noted from admission to discharge in CS and PFT results within each group. Mean percent change in CS and PFT results between CPT and Flutter groups showed no significant difference from hospital admission to discharge. Subsequent power analysis using the observed difference in percent change from admission to discharge for FEV1 indicated that to attain 80% power at alpha = 0.05, a sample of 219 subjects in each group would be necessary. SUMMARY: Comparative trials of airway clearance techniques with sufficient sample size are lacking. Although the Flutter appears to be a useful device for independent, cost-effective, and safe administration of CPT in this pilot study, a much larger clinical trial would be necessary to make definitive conclusions.

The intrapulmonary percussive ventilator and flutter device compared to standard chest physiotherapy in patients with cystic fibrosis.

Stasis of viscid secretions in cystic fibrosis (CF) leads to chronic infection, inflammation, and lung destruction. Chest physiotherapy (CPT) has been used for many years to assist in the removal of these secretions. However, the need for independently administered CPT exists, particularly for adolescents and the older CF patient. Two devices, the intrapulmonary percussive ventilator (IPV) and the Flutter device (Flutter) have been promoted for this purpose. This study compares these devices to standard, manual CPT. There was no difference in sputum quantity produced with any method studied. Transiently lower oxygen saturation was noted with standard CPT compared with the IPV and Flutter. Inconsistent but significant improvements in flow rates were noted with the two devices compared to standard CPT. Important trends to lower lung volumes, probably indicating decreased air trapping, were also noted with all three therapies at 1 and 4 hours after administration. There were no adverse effects with any treatment regimen. Larger and longer studies of these devices compared to standard CPT and with each other are warranted to assess their value for independent administration of CPT in CF patients and to determine long-term effects on maintenance of pulmonary function.

Radical Sphincter preservation surgery with coloanal anastomosis following high-dose external irradiation for the very low lying rectal cancer.

High-dose preoperative radiation and specifically designed surgical techniques were used to extend the application of sphincter preservation surgery for cancer of the distal 3 cm of the true rectum. A total of 203 consecutive patients with rectal cancer were treated with external-beam irradiation (45-70 Gy) and radical curative surgery. The cancer was at the level of 0.5-3.0 cm in 65 patients. In these 65 patients treated by radical resection with coloanal anastomosis six suffered recurrence (9%), and the 5-year actuarial survival was 85%. There was a single death. There was no local recurrence among 44 patients in whom the postradiated cancer resided in the rectal wall with or without nodal involvement. With proper selection, high-dose preoperative radiation therapy thus permits extended use of sphincter preservation surgery with coloanal anastomosis for cancers of the distal 3 cm of the true rectum.