Resection For Right-sided Colon Cancer Research Articles

Surgical treatment and overall survival in patients with right-sided obstructing colon cancer—a nationwide retrospective cohort study

PurposeThe aim of this study was to compare baseline characteristics, 90-day mortality and overall survival (OS) between patients with obstructing and non-obstructing right-sided colon cancer at a national level.MethodsAll patients who underwent resection for right-sided colon cancer between January 2015 and December 2016 were selected from the Netherlands Cancer Registry and stratified for obstruction. Primary outcome was 5-year OS after excluding 90-day mortality as assessed by the Kaplan-Meier and multivariable Cox regression analysis.ResultsA total of 525 patients (7%) with obstructing and 6891 patients (93%) with non-obstructing right-sided colon cancer were included. Patients with right-sided obstructing colon cancer (OCC) were older and had more often transverse tumour location, and the pathological T and N stage was more advanced than in those without obstruction (p < 0.001). The 90-day mortality in patients with right-sided OCC was higher compared to that in patients with non-obstructing colon cancer: 10% versus 3%, respectively (p < 0.001). The 5-year OS of those surviving 90 days postoperatively was 42% in patients with OCC versus 73% in patients with non-obstructing colon cancer, respectively (p < 0.001). Worse 5-year OS was found in patients with right-sided OCC for all stages. Obstruction was an independent risk factor for decreased OS in right-sided colon cancer (HR 1.79, 95% CI 1.57–2.03).ConclusionIn addition to increased risk of postoperative mortality, a stage-independent worse 5-year OS after excluding 90-day mortality was found in patients with right-sided OCC compared to patients without obstruction.

Validation of the German classification system for quality assessment of right-sided colon cancer specimens.

The German classification system of the completeness of mesocolic excision aims to assess the quality of right-sided colonic cancer surgery by review of photographs. We aimed to validate the reliability of the classification in a clinical context. The study was based on a cohort of patients undergoing resection for right-sided colon cancer in two university hospitals served by the same group of pathologists. Prospectively collected photographs of the specimens were assessed twice by six colorectal surgeons to determine the intra-rater and inter-rater accuracy of the German classification and a modification assessing extended right-sided resections. Specimens from 613 resections for right-sided colon cancer were reviewed. Twenty-one specimens were found to be non-assessable, leaving 436 right hemicolectomies, 139 extended right hemicolectomies and 17 right-sided subtotal colectomies. Intra-rater reliability was 0.57-0.74 and weighted kappa coefficients 0.58-0.74, without differences between subgroups. The percentage of agreement between all six participants was 20.3% for all specimens, 21.1% for right hemicolectomy specimens and 18.1% for extended hemicolectomy and right-sided subtotal colectomy specimens. For the right hemicolectomy specimens, the model-based kappa coefficient for agreement was 0.27 (95% CI 0.24-0.30) and for association 0.45 (95% CI 0.41-0.49). The German classification of right hemicolectomy specimens showed low intra-rater reliability and inter-rater agreement and association. The use of this classification for scientific purposes appearednot to be reliable.

Totally laparoscopic resection of right-sided colon cancer using transvaginal specimen extraction with a 10-mm-long abdominal incision.

Natural orifice specimen extraction (NOSE) has been developed as a means of decreasing the incidence of surgical wound complications. We refined the procedure for totally laparoscopic colectomy with transvaginal specimen extraction using the reduced port surgery technique with the ultimate goal of attenuating damage to the abdominal wall. We herein report this innovative technique and its short- and long-term outcomes. We prospectively collected data on seven patients who underwent totally laparoscopic colectomy using transvaginal specimen extraction with a 10-mm-long abdominal incision for right-sided colon cancer from January 2014 to December 2021. Two 5-mm ports were used in the procedure without laparotomy. Transverse transabdominal posterior colpotomy was then performed. We introduced a GelPOINT Mini advanced access platform (Applied Medical, Rancho Santa Margarita, CA, USA) into the transvaginal route for the insertion of a laparoscope, forceps, and stapling device. Lymph node dissection and transection of the ileum and distal colon were performed with transvaginal assistance. A specimen was then extracted transvaginally. Intracorporeal functional end-to-end anastomosis was conducted using a linear stapler through the vagina. After the removal of GelPOINT Mini, the vaginal incision was closed transvaginally. Seven patients successfully underwent this procedure. Median operative time was 219min (range 174-255min), median blood loss was 23ml (range 10-37ml), median number of harvested lymph nodes was 21 (range 17-35 lymph nodes) and median margins were17.0cm (range 9.0-25.0cm) for the proximal margin and 9.5cm (range 5.0-13.0cm) for the distal margin. There were no complications more severe than Clavien-Dindo Grade II and there was no mortality. The median frequency of use intravenous analgesics from postoperative day 1 to discharge was once. Two patients did not require analgesics. A node-positive patient developed recurrence at the lung and paraaortic lymph nodes. This procedure appears to be feasible, safe, and oncologically acceptable for selected cases.

A Comparative Study of the Short-Term Efficacy of Laparoscopic Radical Resection of Right-Sided Colon Cancer with Two Different Surgeon Positions and Trocar Placements

Objective: To investigate the short-term efficacy of laparoscopic radical resection of right-sided colon cancer with two different surgeon positions and trocar placements. Methods: The data of 78 patients who underwent laparoscopic radical resection of right-sided colon cancer between January 2018 and August 2019 were retrospectively analysed. The surgical method was selected by the patients. The patients were divided into two groups according to the surgeons’ positioning habits and trocar placements. The group with the lead surgeon standing between the patient’s legs had 35 patients, and the group with the lead surgeon standing at the left side of the patient had 43 patients. The operation time, intraoperative blood loss, postoperative anal gas evacuation time, postoperative urinary catheter indwelling time, postoperative hospital stay, C-reactive protein (CRP) level on the first day after surgery, and postoperative pathological data and complications were compared between the two groups. Results: All patients underwent the laparoscopic radical resection of right-sided colon cancer, none converting to laparotomy. No significant difference (P > 0.05) in intraoperative blood loss (57.6 ± 21.3 ml vs 60.2 ± 35.3 ml), postoperative anal gas evacuation time (3.5 ± 1.1 d vs 3.8 ± 1.3 d), postoperative urinary catheter indwelling time (2.6 ± 1.3 d vs 2.4 ± 1.2 d), postoperative hospital stay (7.1 ± 1.8 d vs 7.5 ± 2.1 d), or CRP level on the first day after surgery (54.7 ± 9.6 mg/L vs 53.9 ± 8.2 mg/L) was detected between the two groups. The operation time was shorter in the group with the lead surgeon standing between the patient’s legs (185.2 ± 25.6 min vs 196.2 ±19.7 min) (P 0.05). No patients died or had anastomotic fistula during their postoperative hospital stay, and the incidence of postoperative complications did not differ between the two groups (22.9% (8/35) vs 23.3% (10/42); P > 0.05). Conclusion: Under the principle of radical resection, the surgeon should adopt the most suitable standing position and trocar placement according to the specific situation. If the surgeon stands between the patient’s legs, this might shorten the operation time and promote a smoother surgery.

Laparoscopic complete mesocolic excision versus conventional resection for right-sided colon cancer: a propensity score matching analysis of short-term outcomes.

Complete mesocolic excision (CME) for right-sided colon cancer (RCC) is a demanding operation, especially when performed laparoscopically. The potential impact of CME in increasing postoperative complications is still unclear. The aim of our study was to evaluate the safety and feasibility of laparoscopic CME compared with laparoscopic non-complete mesocolic excision (NCME) during colectomy for RCC. Data from a prospectively collected database of patients who underwent laparoscopic right and extended right colectomy at our institution between January 2008 and February 2020 were retrieved and analyzed. Short-term outcomes of patients undergoing CME and NCME were compared. A 1:1 propensity score matching (PSM) was used to balance baseline characteristics between groups. A total of 663 consecutive patients underwent resection of RCC in the study period. Among these, 500 met the inclusion criteria and after PSM a total of 372 patients were correctly matched, 186 in each group. A similar rate of overall postoperative complications was found between the CME and NCME groups (21.5% and 18.3%, p = 0.436). No difference was found in terms of conversion rate, severe complications, reoperations, readmissions, and mortality. The median number of harvested lymph nodes was higher in the CME group (22 versus 19, p = 0.003), with a lower rate of inadequate sampling (7.0% and 15.1%, p = 0.013). Laparoscopic CME for RCC is technically feasible and safe. It does not seem to be associated with a higher rate of complications or mortality compared with the "traditional" approach, but it allows better nodal sampling.

Extended Right Sided Colon Resection Increases the Risk of Post-Operative Complications and Does Not Reduce the Risk of Colon Cancer Local-Regional Recurrence: Nation-Wide Population-Based Study from Danish Colorectal Cancer Group Database

Background: It is controversial whether extensive resection of right-sided colon cancer (RSCC) confer oncological benefits. The aim of this study was to examine short-and long terms outcomes of extended (ERHC) surgical removal of mesocolon compared to conventional approach (CRHC). Method: This was a retrospective population-based study based on a prospectively maintained Danish Colorectal Cancer Group database. Primary outcome measure was local-regional recurrence in patients who underwent curative resection for RSCC and secondary outcome measures was 30-day post-operative complications. Distant metastasis, unplanned intraoperative adverse events (UIAEs), 30-and 90-day post-operative mortality were also investigated. Patients who had palliative or compromised resection, emergency surgery and neo-adjuvant chemo-therapy were excluded. Results: Of the 12,855 patients with RSCC retrieved, 1,151 underwent ERHC. Patients who had ERHC were younger males with a lower ASA scores, operated by colorectal surgeons, using laparoscopic approach and had a significant higher number of harvested lymph nodes.The rate of local-regional recurrence was 1.1% (136/12,855). 1.5% (249/17.174) with no difference between CRHC and ERHC (OR 1.7 CI 95% 0.63-2.18). Post-operative complications were significantly higher in ERHC even after adjusting for age, comorbidity, access to abdomen and other covariates (OR 1.26 CI 95% 1.01-1.58). No significant difference was noticed between CRHC and ERHC in the rates of distant metastasis, UIAEs and mortality. Conclusion: This large population-based registry study showed no difference in local-regional recurrence of RSCC between conventional and extended right hemicolectomy with mesenteric resection and ligation of the middle colic vessels. Extended resection was associated with higher rates of postoperative complications. Funding Statement: None. Declaration of Interests: None Ethics Approval Statement: The data retrieved from DCCG database were fully anonymized so that none of the patient in the dataset could be traced. Data management was conducted according to the national ethical guidelines. Danish Data Protection Agency (Datatilsynet) approval was obtained (RN-2018-94).

Propensity-score-matched analysis of short- and long-term outcomes in patients with an ileocolic artery crossing anterior vs posterior to the superior mesenteric vein during curative resection for right-sided colon cancer

Colorectal cancer is one of the most common malignant diseases worldwide. However, laparoscopic lymph node dissection is technically demanding and time-consuming in right-sided colon cancer surgery because of variable vessel anatomy. We evaluated whether the ileocolic artery (ICA) crossing anterior to the superior mesenteric vein (SMV) was associated with better intraoperative parameters and survival compared with the ICA crossing posterior to the SMV, following laparoscopic curative resection for right-sided colon cancer. This was a propensity-score-matched retrospective study including data for 540 patients with right-sided colon cancer undergoing laparoscopic curative resection (299 with the ICA crossing anterior to the SMV (group A) and 241 with the ICA crossing posterior to the SMV (group B). We compared propensity-matched scores between the two groups to evaluate surgical and oncological outcomes. We found no significant difference in 5-year overall survival rates between groups for any disease stage (0-III). However, 5-year disease-free survival (DFS) rates did differ significantly between groups (p = 0.011), especially in patients with stage III disease (p = 0.013). We then performed univariate and multivariate analyses to determine the associations between DFS and ICA location and tumor-node-metastasis (UICC) stage. ICA location and UICC stage had a poor association with DFS on univariate analysis: ICA hazard ratio (HR) 2.52, CI 1.19-5.78, p = 0.014 vs HR 3.18, CI 1.08-9.46, p = 0.03, and on multivariate analysis: HR 2.48, CI 1.17-5.69, p = 0.016 vs HR 3.86, CI 1.90-7.96, p = 0.0002. Our results showed that an ICA crossing posterior to the SMV was associated with worse DFS compared with an ICA crossing anterior to the SMV. We recommend careful laparoscopic technique in patients with an ICA crossing posterior to the SMV, during lymph node resection in right-sided colon cancer surgery.

Feasibility and application value of autonomic nerve-preserving D3 radical resection for right-sided colon cancer under laparoscope

To explore the feasibility and application value of the preservation of vegetative nervous functions in radical resection for right-sided colon cancer. Clinical data of 55 cases with right-sided colon cancer undergoing laparoscopic D3+ complete mesocolic excision (CME) radical resection from January 2016 to July 2017 at Department of Gastrointestinal Surgery of Guangdong Province Hospital of Traditional Chinese Medicine were retrospectively analyzed. Exclusion criteria included emergency surgery for various reasons, intestinal obstruction or perforation, distant metastasis or locally advanced cancer, previous history of abdominal surgery and preoperative neoadjuvant chemoradiotherapy. Twenty-nine cases underwent lymphadenectomy with intrathecal dissection of superior mesenteric artery (SMA) and part of superior mesenteric plexus was resected (nerve partial resection group, NPR group). Twenty-six cases received lymphadenectomy with the clearance of lymphatic adipose tissue on the right side of SMA by sharp or obtuse method outside the sheath; the sheath of superior mesenteric vein (SMV) was entered at the junction of SMA and SMV; the SMV was naked in the sheath; the third station lymph node dissection was completed with preservation of superior mesenteric plexus (nerve preserved group, NP group). Intra-operative and postoperative complications were compared between two groups. The baseline data were not significantly different between two groups (all P>0.05). The operation time in NP group was significantly shorter than that in NPR group [(164.0±19.8) minutes vs. (176.0±19.7) minutes, t=2.249, P=0.029]. No significant differences in operative blood loss, operative vessel damage, postoperative time to flatus, postoperative hospital stay and abdominal pain were observed between two groups(all P>0.05). The number of harvested lymph node in two groups was 28.5±7.8 and 27.6±6.5 respectively without significant difference(P>0.05). As compared to NPR group, NP group had lower incidence of chylous leakage[3.8%(1/26) vs. 37.9%(11/29), χ²=9.337, P=0.002] and postoperative diarrhea [15.4%(4/26) vs. 41.4%(12/29), χ²=4.491, P=0.034]. Autonomic nerve-preserving D3+ CME radical resection for right-sided colon cancer is safe and feasible, and can prevent the postoperative gastrointestinal dysfunction caused by nerve injury and decrease the risk of chylous leakage.

Defining minimal clearances for adequate lymphatic resection relevant to right colectomy for cancer: a post-mortem study.

There has been a lengthy discussion on the extent of lymphatic resection for right-sided colon cancer and the central borders of the mesentery that are not yet defined. The objectives of this study are to define minimal clearances for adequate lymphatic resection in regard to colic artery origins and the superior mesenteric artery (SMA) and vein (SMV) relevant to right colectomy. Central mesenteric lymph vessels, nodes, and blood vessels were dissected in 16 cadavers. Cranial-caudal clearances were defined as distances between an individual colic artery origin (ileocolic, right colic, and median colic artery) and the outermost lymphatic vessel within its lymphovascular bundle, cranial and caudal along the SMA. Long lymphatic vessels crossing the SMV between arterial bundles were counted and they constituted the medial clearances. An arbitrary watershed between small bowel and colonic lymph was localized. Immunohistochemistry was performed to histologically verify lymphatic vessels. Cranial-caudal clearances were ileocolic 3.6 ± 1.9 and 5.7 ± 1.9; right colic 2.8 ± 1.6 and 3.3 ± 1.0; middle colic artery bundle 6.3 ± 2.7 and 5.9 ± 2.4mm, respectively. Long lymphatic vessels crossing the SMV between arterial buntles and approaching the SMA were found in all cadavers (antero/posteriorly in 12, only anteriorly in 4), median 3.5 (1-7) long lymphatic vessels anteriorly, and 1.5 (0-5) posteriorly per cadaver. Right colonic lymphovascular bundles are volumes of mesenteric tissue that surround the superior mesenteric vessels anteriorly and posteriorly. Long lymphatic vessels traverse the superior mesenteric vein anteriorly/posteriorly approaching the superior mesenteric artery between arterial bundles and placing the medial clearance on the left side of the artery. These do not correlate to arterial crossing patterns. Cranial-caudal clearances determine the tissue to be removed superior/inferior to arterial origins together with long lymphatic vessels transversing independently between the lymphovascular bundles placing the weight of lymphatic resection on the mesenteric tissue and not on the level of vessel division (High tie).

Laparoscopic caudal-to-cranial approach for radical lymph node dissection in right hemicolectomy.

The present study evaluated the safety and feasibility of this caudal-to-cranial laparoscopic dissection approach for the curative resection of right-sided colon cancer. To the best of our knowledge, no study has reported the caudal-to-cranial approach in the laparoscopic right colectomy with curative intent for colon cancer. The key procedure of the caudal-to-cranial approach is the commencement of the dissection atthe mesentery root, thus entering into the Toldt's space before the mesenteric vessels are accessed. We retrospectively analyzed the data obtained from a prospectively established database on 80 consecutive patients who had undergone laparoscopic right hemicolectomy with caudally approached radical lymph node dissection for curable right-sided colon cancer between June 2014 and June 2015. There were 38 male and 42 female patients, with a mean age of 72.5years (range, 53-83) and a mean BMI of 22.1kg/m(2) (16.5-35.2). All procedures were successful without any serious intraoperative complications or any conversion to open surgery. The mean operation time was 178.3min (range, 150-215), and the mean blood loss was 81.6ml (range, 50-200). The mean number of harvested lymph nodes was 19 (range, 12-25). The findings indicate that laparoscopic caudal-to-cranial approach for radical lymph node dissection is a feasible and safe procedure for the treatment of curable right-sided colon cancer.

Learning curve for single-incision laparoscopic resection of right-sided colon cancer by complete mesocolic excision.

Single-incision laparoscopic surgery is cosmetically beneficial, but technically challenging. In this study, the learning curve (LC) for single-incision laparoscopic right hemicolectomy (SILRC), incorporating complete mesocolic excision to resect right-sided colon cancer, was investigated through multidimensional techniques. Between December 2009 and May 2015, 64 patients each underwent SILRC of right-sided colon cancer at Severance Hospital, performed in all instances by the same surgeon. Moving average and cumulative sum control chart (CUSUM) were used for LC analyses retrospectively. Surgical failure was defined as conversion to conventional laparoscopic surgery, postsurgical morbidity within 30 days, harvested lymph node count <12, or local tumor recurrence. Both moving average and CUSUM graphics of operative time registered nadirs at the 24th patient, with slight ascent thereafter, reaching a plateau at the 40th patient. The CUSUM for surgical success peaked at the 23rd patient. Operative time for 23 patients in phase 1 (1–23) and for 41 patients in phase 2 (24–64) of the LC did not differ significantly. By comparison, significant differences in patients of phase 2 included larger tumor size, higher harvested lymph node counts, longer proximal resection margins, and more advanced disease. As indicated by multidimensional statistical analyses, the LC for SILRC of right-sided colon cancer was 23 patients. In terms of operative time and surgical success, SILRC is feasible for surgeons experienced in LS, but may prove more challenging for novices, given the fundamental technical difficulties of this procedure.

Lymphadenectomy for Colon Cancer: Is There a Consensus?

In this issue of Annals of Surgical Oncology, Park et al. present an interesting study analyzing patterns of lymph node metastasis in patients with right-sided colon cancer. 1 With a large cohort of 419 patients, they studied the distribution of lymph nodes metastasis along the different arteries of right and transverse colon according to the location of adenocarcinoma. For cancer located from cecum to hepatic flexure, they found lymph node metastasis along ileocolic artery, right colic artery, and middle colic artery. For proximal transverse colon cancer, no lymph node metastasis was found along ileocolic artery. On the basis of their results, they propose some guidelines for surgical resection of right-sided colon cancer: ileocecal resection for cecal cancer does not seem oncologically safe, and resection preserving ileocolic artery and ileocolic valve performed for transverse colon cancer seems reasonable.

Lymph Node Metastasis Patterns in Right-Sided Colon Cancers: Is Segmental Resection of These Tumors Oncologically Safe?

The type of surgery and the extent of lymphadenectomy depend on the tumor location and should be based on the extent of lymphatic spread and the oncologic outcome. The aim was to analyze patterns of lymph node metastasis in patients with right-sided colon cancer. Between 1996 and 2007, a total of 419 patients underwent curative resection for right-sided colon cancer. Lymph nodes were grouped immediately after surgery on the basis of the location of the tumor. There were 75, 208, 78, and 58 tumors in the cecum, ascending colon, at the hepatic flexure, and in the transverse colon, respectively. Of the 58 patients with transverse colon tumors, 43, 11, 3, and 1 underwent right hemicolectomies, transverse colectomies, left hemicolectomies, and a subtotal colectomy, respectively. Patients with cecal and ascending colon cancers most frequently had metastases in the ileocolic lymph nodes. Metastasis to the lymph nodes along the right branch of the middle colic artery occurred in 6.1% of patients with cecal cancer. In patients with hepatic flexure cancers, the epicolic lymph nodes along the right and middle colic arteries were most commonly metastatic lymph nodes. In transverse colon cancer, the middle colic node was the most commonly involved lymph node. Approximately 10% of patients had metastases to the right colic nodes. Metastasis to lymph nodes along the right colic artery occurred in approximately 10% of the patients with transverse cancer, indicating the need for great care in deciding the extent of segmental resection for these patients.

Laparoscopic Medial-to-lateral Approach for the Curative Resection of Right-Sided Colon Cancer

Our previous randomized clinical trial comparing the laparoscopic medial-to-lateral dissection with the more classic lateral-to-medial approach for resection of rectosigmoid cancer showed that the medial approach reduces the operative time and the postoperative proinflammatory response. Besides the oncologic advantages of an early vessel division and a "no-touch" dissection, we feel that the longer the lateral abdominal wall attachments of the colon are preserved, the better the exposure and the easier the dissection. Encouraged by the above-mentioned positive findings, we therefore further conduct this phase II clinical trial to examine the feasibility and surgical outcomes regarding the utilization of this medial-to-lateral laparoscopic dissection approach for the curative resection of right-sided colon cancer. A total of 104 patients (from December 2000 to January, 2005) with advanced right-sided colon cancer (TNM stage II: n = 56; stage III: n = 48) requiring a curative right hemicolectomy were subjected to the laparoscopic medial-to-lateral approach that included initial exploration and ligation of ileocolic, right colic, and middle colic vessels in no-touch isolation fashion, subsequent medial-to-lateral extension of retroperitoneal dissection along Gerota fascia, opening of lesser sac by transection of gastrocolic ligament, and the final mobilization of hepatic flexure and lateral attachments of ascending colon (Fig. 1). This study was approved by the institutional review committee of National Taiwan University Hospital. The surgical details were shown in the video. Postoperatively, adjuvant chemotherapy with Mayo Clinic Regimen was given in patients with stage III diseases. The functional recovery and surgical outcomes were prospectively evaluated. The laparoscopic medial-to-lateral approach for a curative right hemicolectomy can be preformed with acceptable operation time (192.6 +/- 32.8 min, mean +/- standard deviation) and little blood loss (48.4 +/- 14.4 ml) through a small wound (6.0 +/- 0.8 cm). The number of dissected lymph node was 16.0 +/- 2.8. The operative complications represented 5.7% of all cases, including anastomotic leakage in two cases (1.9%) and wound infection in four cases (3.8%). The patients have quick functional recovery, as evaluated by the length of postoperative ileus (60.0 +/- 12.0 h), hospitalization (9.0 +/- 1.5 days) and degree of postoperative pain (4.0 +/- 0.5, visual analogue scale). Besides the expenses covered by the National Bureau of Health Insurance in Taiwan, the patient had to pay an extra-expenses of NT$ 25,000.0 +/- 2,800.0 (1.0 US$ = 32.0 NT$). During the follow-up periods (median: 30 months, range 6-55 months), recurrence of tumor developed in 6 (10.7%) of stage II and 10 (20.8%) of stage III patients, with liver metastasis in six patients, lung metastasis in 4, liver and lung metastasis in 1, intraperitoneal recurrence in 2, bone metastasis in 1, brain metastasis in 1, and port-site recurrence in 1. By medial-to-lateral dissection method, the laparoscopic right hemicolectomy can be performed with technical efficiency, short convalescence, and acceptable short-term oncologic results. We therefore encourage the use of this approach for patients requiring a curative laparoscopic right hemicolectomy.

Colonoscopic miss rates for right-sided colon cancer: A population-based analysis

Background & Aims: Colonoscopy contains an inherent miss rate for colorectal cancer. Although miss rates from academic centers or units known for their endoscopic expertise have been previously reported, the colorectal cancer miss rate of colonoscopy performed in usual clinical practice is unknown. We conducted a population-based study to estimate the proportion of right-sided colon cancers missed during colonoscopy in Ontario. Methods: All persons ≥20 years old with a new diagnosis of right-sided colon cancer admitted to the hospital for surgical resection in Ontario from April 1, 1997, to March 31, 2001, were identified. Patients who had a colonoscopy within 3 years of their diagnosis were divided into 2 groups: detected cancers (those who had a colonoscopy up to 6 months before the diagnosis) and missed cancers (those who had a colonoscopy between 6 and 36 months before the diagnosis). Data were obtained from the Canadian Institute for Health Information Discharge Abstract Database, the Ontario Health Insurance Plan database, and the Registered Persons Database. Results: Between April 1, 1997, and March 31, 2001, we identified 4920 persons with a new diagnosis of right-sided colon cancer, of whom 2654 (53.9%) had had at least 1 colonoscopy within 3 years of their admission for surgical resection. Most (96.0%) had had their most recent colonoscopy up to 6 months before admission (detected cancers). However, 105 patients (4.0%) had their most recent colonoscopy between 6 and 36 months before admission to the hospital (missed cancers). Conclusions: Among persons undergoing resection for right-sided colon cancer, the miss rate of colonoscopy for detecting cancer in usual clinical practice was 4.0%.

CT of Patients with Right-Sided Colon Cancer and Distal Ileal Thickening

The purpose of this study was to analyze the incidence and primary causes of distal ileal wall thickening in 131 patients with right-sided colon cancer. During a 2-year period, 131 patients underwent surgical resection for right-sided colon cancer. Of these patients, we analyzed 13 who had distal ileal wall thickening on CT before surgery and also had the cause determined at pathology. CT findings were analyzed with regard to the morphologic features of colonic tumors, bowel wall involvement patterns of the distal ileum, and changes in the pericolic space. Distal ileal wall thickening occurred in 13 (10%) of the 131 patients who had right-sided colon cancer. Three patients had polypoid colon cancer, whereas the other 10 had infiltrative colon cancer. The mean thickness of the involved colonic segments was 1.6 cm (range, 1.0-2.2 cm) with a mean length of 5.2 cm (range, 2.5-10.0 cm). Pericolic infiltration was mild in six patients and moderate in four patients. The mean length and thickness of the affected ileal segments were 3.2 cm (range, 1.5-6.0 cm) and 1.1 cm (range, 0.7-2.0 cm), respectively. On histopathologic examination, neoplastic processes involved the distal ileum in nine (69%) of the 13 patients. This involvement was caused by either direct tumor invasion in seven patients or lymphatic spread in two. In four patients (31%), nonneoplastic processes with edema and congestion involved the distal ileum. The distal ileum may be abnormally thickened in about 10% of patients with right-sided colon cancer; this thickening results from tumor extension (69%) or a nontumorous process (31%).