P. W. R. Lee

Artificial neural networks applied to outcome prediction for colorectal cancer patients in separate institutions

BACKGROUND Artificial neural networks are computer programs that can be used to discover complex relations within data sets. They permit the recognition of patterns in complex biological data sets that cannot be detected with conventional linear statistical analysis. One such complex problem is the prediction of outcome for individual patients treated for colorectal cancer. Predictions of outcome in such patients have traditionally been based on population statistics. However, these predictions have little meaning for the individual patient. We report the training of neural networks to predict outcome for individual patients from one institution and their predictive performance on data from a different institution in another region. METHODS 5-year follow-up data from 334 patients treated for colorectal cancer were used to train and validate six neural networks designed for the prediction of death within 9, 12, 15, 18, 21, and 24 months. The previously trained 12-month neural network was then applied to 2-year follow-up data from patients from a second institution; outcome was concealed. No further training of the neural network was undertaken. The networks predictions were compared with those of two consultant colorectal surgeons supplied with the same data. FINDINGS All six neural networks were able to achieve overall accuracy greater than 80% for the prediction of death for individual patients at institution 1 within 9, 12, 15, 18, 21, and 24 months. The mean sensitivity and specificity were 60% and 88%. When the neural network trained to predict death within 12 months was applied to data from the second institution, overall accuracy of 90% (95% CI 84-96) was achieved, compared with the overall accuracy of the colorectal surgeons of 79% (71-87) and 75% (66-84). INTERPRETATION The neural networks were able to predict outcome for individual patients with colorectal cancer much more accurately than the currently available clinicopathological methods. Once trained on data from one institution, the neural networks were able to predict outcome for patients from an unrelated institution.

Patterns of Recurrence and Survival After Laparoscopic and Conventional Resections for Colorectal Carcinoma

ObjectiveTo determine whether survival and recurrence after laparoscopic-assisted surgery for colorectal cancer is compromised by an initial laparoscopic approach. Summary Background DataLaparoscopic colorectal resection for malignancy remains controversial 8 years after its first description. Fears regarding compromised oncologic principles and early recurrence (particularly the phenomenon of port-site metastases) have tempered enthusiasm for this approach. Long-term follow-up data are at present scarce. MethodsA prospective comparative trial was undertaken between December 1993 and May 1996, during which 114 patients had laparoscopic-assisted resection by a single laparoscopic colorectal surgeon or conventional open surgery by a second specialist colorectal surgeon. Intensive follow-up for at least 2 years is available on 109 patients. Analysis was performed on an intention-to-treat basis. ResultsRecurrent disease has developed in 27 patients (25%), 16 of 57 in the laparoscopic group (28%) and 11 of 52 in the conventional group (21%). Crude death rates are 26/57 (46%) in the laparoscopic group and 24/52 (46%) in the conventional group. No port-site metastases have occurred; however, wound metastases associated with disseminated disease have developed in three patients in the open group and one in the laparoscopic group. Stage-for-stage survival and recurrence figures are comparable. ConclusionOncologic outcome at a minimum of 2 years is not compromised by the laparoscopic approach. Wound recurrences are a feature of laparoscopic and conventional surgery for advanced disease.

Endosonographic evidence of injury to the internal anal sphincter after low anterior resection: long-term follow-up.

PURPOSE: Transanal stapled anastomosis has been associated with continence disturbances and reduced postoperative anal sphincter function. The aim of the present work was to study the effect of transanal stapling on anal sphincter morphology by endoanal ultrasound. METHODS: Thirty-nine consecutive patients undergoing stapled low anterior resection for rectal carcinoma were assessed. Each patient was assessed by endoluminal ultrasound before surgery, immediately after surgery, and at 3, 6, 9, 12, and 24 months after surgery. RESULTS: There were no preoperative internal and sphincter defects observed. Three female patients were observed to have preoperative evidence of external anal sphincter defects. After low anterior resection, seven patients were found to have internal anal sphincter defects, which persisted after the two-year follow-up. There were no additional external anal sphincter injuries. Three patients with internal anal sphincter injuries required the use of pads for poor bowel function. CONCLUSIONS: Up to 18 percent of patients who underwent stapled low anterior resection had long-term evidence of internal anal sphincter injury. The external sphincter does not appear to be affected by the procedure.

Does laparoscopic abdominoperineal resection of the rectum compromise long-term survival?

AbstractPURPOSE: Laparoscopic techniques for bowel resection have not enjoyed widespread popularity. Of concern is that long-term follow-up data of cancer specific outcomes is not yet available. The aim of our study was to examine the long-term outcome of abdominoperineal resection for cancer done laparoscopically compared with a similar cohort who underwent open surgery. METHODS: A retrospective review was performed of all abdominoperineal resections done in our center between 1992 and 2000, comparing the cancer-specific outcomes of the laparoscopic cohort with the open cohort. The analysis was performed on an intention-to-treat basis and survival analysis was calculated by the techniques of Kaplan-Meier. RESULTS: Eighty-nine patients were reviewed. Twenty-eight operations were done laparoscopically, and 61 were open. The two groups were matched for age and stage of disease. There was no difference in mean length of overall survival (open = 30.3 months; laparoscopic = 40.8 months; P = 0.355 log rank). No difference in overall recurrence rate, isolated recurrence rate, or distant recurrence rates was seen nor was there any difference in the disease-free period. There was no difference in the number of lymph nodes harvested from the resected specimens, and the distance to the lateral margins or involvement of tumor in the lateral margins between the two groups was the same. The laparoscopic cohort did have a significantly shorter length of stay (mean, 13 days) compared with the open cohort (mean, 18 days), P = 0.008 Mann-Whitney U test. CONCLUSIONS: Laparoscopic abdominoperineal resection of the rectum for cancer does not compromise cancer-specific survival outcomes. The patients avoid a large abdominal wound, which improves cosmesis and presumably is responsible for the significantly shorter length of stay.

Changes in T cell subsets, interleukin-6 and C-reactive protein after laparoscopic and open colorectal resection for malignancy

Background: Attenuation of the immune response to surgery, as demonstrated with the laparoscopic approach to cholecystectomy, has potential benefits in patients undergoing laparoscopic colonic resection for malignancy. We aimed to study the perioperative immune response in patients undergoing laparoscopically assisted and open surgery for colorectal cancer. Methods: This study involved 23 patients undergoing laparoscopically assisted (n = 13) and open surgery (n = 10). Interleukin-6 (IL-6) C-reactive protein (CRP), the total lymphocyte count, and the CD3, CD4, CD8, CD16, and CD19 lymphocyte subpopulations were assayed preoperatively and at 4, 8, 10, 24, 48, and 168 h postoperatively. Results: Significant rises in IL-6 and CRP were demonstrated within 4 and 24 h, respectively (p < 0.001) in both groups. However, no significant difference between the groups was seen. Significant decreases in total lymphocyte count and all T cell subsets were demonstrated in both groups, beginning at 4 h (p < 0.01). However, no significant difference between the groups was seen. All parameters, excluding CRP, had returned to baseline by 7 days postoperatively in both groups. Conclusions: Patients with malignancy exhibit significant perioperative immune disturbance with laparoscopically assisted and open surgery. The current data do not provide justification for the laparoscopically assisted approach on grounds of immune preservation.

Vaginography—Investigation of choice for clinically suspected vaginal fistulas

PURPOSE: Vaginal fistulas are rare but can cause extremely distressing symptoms for patients and prove difficult to define anatomically. Barium studies have been reported as having a maximum sensitivity of only 34 percent for detection of vaginal fistulas. Vaginography is an alternative method for diagnosis and evaluation of suspected vaginal fistulas, which has been reported to have a sensitivity of 100 percent. We reviewed our total experience of vaginography to fully assess its capabilities. METHODS: Twenty-seven patients with clinically suspected vaginal fistulas were investigated with vaginography during a six-year period. Results of vaginograms were compared with final operative or clinical diagnosis and with results of other radiologic investigations. RESULTS: Vaginography successfully identified 19 of 24 fistulas, giving a sensitivity of 79 percent. In our series, barium enema was only able to identify 9 percent of fistulas arising from the colon. CONCLUSIONS: In this, the largest series of vaginograms, apparent reduction in sensitivity from the 100 percent quoted in earlier series to 79 percent probably represents a more accurate assessment of vaginography as a diagnostic investigation. Even allowing for this reduction, vaginography is still the most sensitive, economic, and informative investigation for identification and delineation of vaginal fistulas. We recommend that vaginography be the initial investigation of choice in patients with clinically suspected vaginal fistulas.

A Case-Control Study of Laparoscopic Right Hemicolectomy vs. Open Right Hemicolectomy

PURPOSEThe purpose of our study was to examine all laparoscopic right hemicolectomies performed for cancer in our unit and to compare them with a case-control series of open right hemicolectomies, with emphasis on long-term survival.METHODSIn a retrospective case-control series of right hemicolectomies, those done laparoscopically were compared with an age-matched and stage-matched series of patients who underwent open surgery. Survival was analyzed with the Kaplan-Meier method.RESULTSNinety-nine patients were included in the study, 33 laparoscopic and 66 open. Mean age 69.7 years. Dukes staging was the same between the two groups and mean follow-up period was 65.7 months. There were six laparoscopic conversions. The number of days patients were kept nil by mouth was significantly less in the laparoscopic cohort, with a mean of 2.4 days vs. a mean of 3.65 days (P = 0.005, Mann-Whitney U test). The number of days during which patients required parenteral opiates was significantly less in the laparoscopic cohort, with a mean number of days of 2.5, in contrast to 4.5 days in the open group (P = 0.008, Mann-Whitney U test). When overall survival was compared between the open and laparoscopic groups, no difference was found, with a mean overall survival of 40 months in the laparoscopic cohort and 39.4 months in the open cohort (P = 0.348, log-rank test).CONCLUSIONLaparoscopic right hemicolectomy for cancer does not compromise long-term survival and affords the advantage of a shorter period of postoperative ileus and decreased analgesia requirements.

Staged delivery of Nd:Yag laser therapy for palliation of advanced rectal carcinoma

PURPOSE: This study was designed to assess the degree of symptom relief, complication rate, and survival time of patients who undergo palliation with the neodymiumyttrium aluminum garnet (Nd:YAG) laser for advanced rectal cancer. METHODS: Charts of 41 consecutive patients with advanced rectal cancer treated by this method were reviewed. RESULTS: Thirty-three patients received laser treatment for a primary tumor, and eight received laser palliation for local recurrence following previous surgery. Mean number of treatments delivered was 2 (range, 1–6) for patients with a primary lesion and 2 (range, 1–4) for those patients with local recurrence. In patients in whom more than one delivery was required, subsequent procedures were deferred for more than six weeks. Morbidity rate was 2 percent, with no procedure-related mortality. Median survival time was 19 (range, 1–60) months for patients with a primary tumor and 7 (range, 3–38) months for patients with local recurrence. Four patients subsequently elected to undergo palliative surgery, and five other patients had a loop colostomy formed because of large-bowel obstruction after a mean of 24 (range, 18–41) months. Nd:YAG laser treatment offered adequate laser palliation for 78 percent of patients in this series. However, patients who survive for more than 24 months after their first laser treatment are more likely to require palliative surgery. CONCLUSIONS: The majority of patients undergoing laser ablation for palliation do not require large numbers of treatment sessions. By delaying the interval between treatments, morbidity and mortality rates are negligible. Most patients avoid a stoma or defer the date of requiring one before their death with this therapy.

Transanal MULTIFIRE ENDO GIA technique for rectal polypectomy.

Difficulty in access for local resection of broad-base rectal polyps in the mid rectum can present a management problem. Transanal use of the MULTIFIRE ENDO GIA®provides a hemostatic excision of these rectal polyps.

Double stapled transabdominal anastomosis for one-stage resection of acute sigmoid volvulus

A double stapling technique is described for the restoration of colonic continuity in patients undergoing sigmoid colectomy for volvulus.