Prognostic value of direct spread in Dukes' C cases of rectal cancer

How Should Imaging Direct/Orient Management of Rectal Cancer?

Modern rectal cancer management is dependent on preoperative staging, and radiological assessment is a crucial part of this process. Imaging must provide sufficient information to guide preoperative decision-making that is reliable and reproducible. Different methods have been used for local staging; however, magnetic resonance imaging (MRI) has shown to be the most reliable tool for this purpose. MRI offers prognostic information about the patients and guides the decision between neoadjuvant treatment and total mesorectal excision alone. Also, not only the initial staging but also restaging by MRI can provide significant information regarding tumor response that is essential when considering alternative approaches.

Assessment of aggressiveness of rectal cancer using 3-T MRI: correlation between the apparent diffusion coefficient as a potential imaging biomarker and histologic prognostic factors

BACKGROUND

Diffusion-weighted magnetic resonance imaging (DW-MRI) permits non-invasive assessment of tumor characteristics.

PURPOSE

To assess the value of DW-MRI as a potential non-invasive marker of tumor aggressiveness in rectal cancer by analyzing the relationship between tumoral apparent diffusion coefficient (ADC) values of MRI and histopathologic prognostic parameters that are not affected by preoperative chemoradiation therapy.

MATERIAL AND METHODS

Forty patients with rectal cancer were assessed with primary staging 3-T MRI, including DWI, before undergoing surgical therapy. In all patients, surgery was performed without neoadjuvant therapy. Mean tumor ADC was measured and compared between subgroups based on pretreatment carcinoembryonic antigen (CEA) levels, MRI parameters (e.g. postoperative local recurrence), and histopathologic parameters, including A (invasive distance: A1, T-stage; A2, mesorectal fascia [MRF] status), B (differentiation grade: B1, poorly differentiated; B2, moderately differentiated; B3, well differentiated), C (others: C1, N-stage; C2, lymphangiovascular invasion).

RESULTS

Mean tumor ADCs were different when comparing groups stratified by histologic differentiation grades (P=0.0192). There was no significant difference in mean ADCs when stratifying patients according to CEA levels, T-stage, N-stage, MRF status, presence of lymphangiovascular invasion, or the presence of local recurrence.

CONCLUSION

Significant correlations were found between mean ADC values and differentiation grade. ADC may be useful as an imaging biomarker of tumor aggressiveness, but it cannot serve as an independent biomarker of advanced rectal cancer.

Extramural depth of tumor invasion at thin-section MR in rectal cancer: associating with prognostic factors and ADC value

PURPOSE

To assess the value of maximal extramural depth (EMD) of T3 tumor spread on MRI as a potential noninvasive imaging biomarker of tumor aggressiveness in rectal cancer, by analyzing the relationship between tumoral EMD values and clinical or histological prognostic parameters. In addition, we try to investigate the relationship between EMD and apparent diffusion coefficient (ADC) values.

MATERIALS AND METHODS

Ninety rectal cancer patients who underwent primary MRI staging and diffusion weighted imaging (DWI) as T3 tumor were included. Tumor EMD was measured, and the EMD values of the subgroups based on pretreatment CEA, CA19-9 levels, N stage, and histological parameters were compared. The correlation between EMD and ADC values was compared.

RESULTS

Interobserver agreement of confidence levels for observers 1 and 2 was good for cN stage (k = 0.678) and EMD measurement(k = 0.612) and was excellent for ADC measurement (k = 0.880). Tumor EMDs differ between CEA <5 ng/mL versus ≥ 5 ng/mL (P = 0.013), CA19-9 < 27 U/mL versus ≥ 27 U/mL (P = 0.012), the groups of cN0 versus cN+ cancers (P = 0.049), and between the several groups of histological differentiation grades (P = 0.033). There was no significant difference in EMDs between the various groups of vessel carcinoma embolus and neural invasion. A significant negative correlation (r = -0.581; P = 0.001) between ADC and EMD values was found.

CONCLUSION

Significant correlations were found between EMD values and CEA, CA19-9 level, differentiation grade and ADC value. As been found, higher EMD values were associated with a more aggressive tumor profile and, therefore, EMD has the potential to become an imaging biomarker of tumor aggressiveness indicator.

Apparent diffusion coefficient as a non-invasive predictor of treatment response and recurrence in locally advanced rectal cancer

AIM

To evaluate the role of pretreatment apparent diffusion coefficient (ADC) as a predictor of treatment response and local recurrence in patients with locally advanced rectal cancer who underwent neoadjuvant therapy.

MATERIALS AND METHODS

Forty-nine patients who underwent preoperative diffusion-weighted magnetic resonance imaging (MRI) followed by neoadjuvant chemoradiation and surgery were enrolled in the study. The mean tumour ADC was measured independently from multiple, non-overlapping regions of interest (ROIs) to cover the entire tumour area on a single section by two radiologists and patients were followed postoperatively for a median of 16.4 months. Diagnostic accuracy of ADC for predicting treatment response and recurrence was evaluated using the area under the receiver-operating characteristic (ROC) curve, sensitivity, specificity, and predictive values. Univariate and multivariate analyses including clinical tumour (cT) staging, carcinoembryonic antigen (CEA) level, lymph-node involvement, tumour grade, surgical margin, vascular involvement, and ADC were performed with respect to recurrence. Interobserver agreement of ADC values was assessed.

RESULTS

Twenty patients showed response to neoadjuvant therapy and recurrence was noted in 17 patients. Low pretreatment ADC, MRI findings of cT4 staging, and node involvement were significantly related to poor treatment response. Sensitivity and specificity of ADC = 0.833 × 10(-3) mm(2)/s for prediction of treatment response was 75 and 48% for reader 1 and 65 and 52% for reader 2, respectively. Univariate and multivariate analyses identified pretreatment tumour ADC as the only predictive factor for recurrence. Sensitivity and specificity of ADC = 0.833 × 10(-3) mm(2)/s for prediction of recurrence was 86 and 77% for reader 1 and 80 and 69% for reader 2, respectively. Interobserver agreement for measuring ADC was good with a kappa value of 0.70.

CONCLUSION

Pretreatment rectal tumour ADC values may be an early biomarker for predicting treatment response and local recurrence in patients who underwent neoadjuvant chemoradiation.

Diffusion-weighted MRI in rectal cancer: apparent diffusion coefficient as a potential noninvasive marker of tumor aggressiveness

PURPOSE

To assess the value of diffusion-weighted MR imaging (DWI) as a potential noninvasive marker of tumor aggressiveness in rectal cancer, by analyzing the relationship between tumoral apparent diffusion coefficient (ADC) values and MRI and histological prognostic parameters.

MATERIALS AND METHODS

Fifty rectal cancer patients underwent primary staging MRI including DWI before surgery and neo-adjuvant therapy. In 47, surgery was preceded by short-course radiation therapy (n = 28) or long-course chemoradiation therapy (n = 19). Mean tumor ADC was measured and compared between subgroups based on pretreatment CEA levels, MRI parameters (mesorectal fascia - MRF - status; T-stage; N-stage) and histological parameters (differentiation grade: poorly differentiated, poorly moderately differentiated, moderately differentiated, moderately well differentiated, well-differentiated; lymphangiovascular invasion).

RESULTS

Mean tumor ADCs differ between MRF-free versus MRF-invaded tumors (P = 0.013), the groups of cN0 versus cN+ cancers (P = 0.011), and between the several groups of histological differentiation grades (P = 0.025). There was no significant difference in mean ADCs between the various groups of CEA levels, the T stage, and the presence of lymphangiovascular invasion.

CONCLUSION

Lower ADC values were associated with a more aggressive tumor profile. Significant correlations were found between mean ADC values and radiological MRF status, N stage and differentiation grade. ADC has the potential to become an imaging biomarker of tumor aggressiveness profile.

Preoperative staging of rectal cancer

Preoperative staging is now an essential factor in the multidisciplinary management of rectal cancer because tumor stage is the strongest predictive factor for recurrence. Preoperative staging of rectal cancer can be divided into either local or distant staging. Local staging incorporates the assessment of mural wall invasion, circumferential resection margin involvement, as well as the nodal status for metastasis. Distant staging assesses for evidence of metastatic disease. The aim of this review is to consider the indications and limitations of the current preoperative imaging modalities for rectal cancer staging including clinical examination, endorectal ultrasound, magnetic resonance imaging, computed tomography and positron emission tomography–computed tomography, with respect to local and distant disease.

Prognostic value of clinical, pathological and immunohistochemical markers in stage II colon cancer patients

BACKGROUND/AIMS

The purpose of our analysis was to determine the prognostic value of molecular markers for identifying high-risk TNM stage II colon cancer patients, the association with various clinical and pathological features, and possible relation to survival.

METHODS

In 191 colon cancer patients who underwent a potentially curative resection, clinical and pathological factors (age, tumour site, histological grade of malignancy, pT stage, presence of venous, lymphatic and perineural invasion) and tumour molecular markers were analysed. Molecular markers were assessed immunohistochemically in sections of paraffin-embedded tissues. Patients were followed for a median of 8.7 years. The 5-year survival rate was estimated using the the Kaplan-Meier statistical method.

RESULTS

From 1. Jan. 1994 to 31. Dec. 2000, 191 patients underwent radical resection for T3-4 N0M0 colorectal cancer without adjuvant chemotherapy. A significant decrease in survival was identified in older patients, patients with tumours pT4 and with perineural invasion. We found no significant differences in survival of patients with expression of MLH1, Cyclin D1 and reduced overexpression of E-cadherin.

CONCLUSIONS

The results of our study indicate that the presence of perineural invasion, pT4 stage and the patient's age are significantly correlated with the expected survival in radically resected TNM stage II colon cancer patients, while immunohistochemical markers are not related to survival.

A systematic approach to the interpretation of preoperative staging MRI for rectal cancer

OBJECTIVE

The purpose of this article is to provide an aid to the systematic evaluation of MRI in staging rectal cancer.

CONCLUSION

MRI has been shown to be an effective tool for the accurate preoperative staging of rectal cancer. In the Magnetic Resonance Imaging and Rectal Cancer European Equivalence Study (MERCURY), imaging workshops were held for participating radiologists to ensure standardization of scan acquisition techniques and interpretation of the images. In this article, we report how the information was obtained and give examples of the images and how they are interpreted, with the aim of providing a systematic approach to the reporting process.

Rectal Cancer: MR Imaging before Neoadjuvant Chemotherapy and Radiation Therapy for Prediction of Tumor-Free Circumferential Resection Margins and Long-term Survival1

PURPOSE

To retrospectively evaluate the prognostic importance of involvement of the circumferential resection margin predicted by using magnetic resonance (MR) imaging before neoadjuvant treatment in patients with rectal cancer.

MATERIALS AND METHODS

The local institutional review board approved the retrospective analysis of the data and waived informed consent. Sixty-eight patients (52 men, 16 women; mean age +/- standard deviation, 58.9 years +/- 9.4) with cT3 NX M0 tumors were included. T2-weighted MR images were analyzed in consensus by two radiologists with respect to the shortest distance between the outermost parts of the tumor to the adjacent mesorectal fascia (as the potential circumferential resection margin in total mesorectal excision). Histopathologic and follow-up data were available for all patients (mean follow-up time, 54 months; range, 31-77 months). To compare local recurrence and survival rates, the population was divided into three groups categorized according to the minimum distance of the tumor to the mesorectal fascia (group 1, <or=1 mm; group 2, >1 to 5 mm; group 3, >5 mm). Univariate Cox and multivariate proportional hazard regression models were used to test the prognostic importance of clinical, histopathologic regression, and histopathologic tumor parameters.

RESULTS

MR imaging led to accurate prediction of a histologically involved circumferential resection margin (sensitivity, 100%; specificity, 88%). The rates for local recurrence (group 1, 33%; group 2, 5%; group 3, 6%; P<.02) and 5-year overall survival (group 1, 39%; group 2, 70%; group 3, 90%; P<.001) differed significantly among the predefined groups. The distance to the mesorectal fascia was an independent prognostic parameter in multivariate analysis (P<.001), and histopathologic response to treatment provided no additional information.

CONCLUSION

Prediction of the tumor-free circumferential resection margin assessed with MR imaging before initiation of neoadjuvant chemotherapy and radiation therapy proved to be a prognostic factor in rectal cancer.

Recommendations for the reporting of surgically resected specimens of colorectal carcinoma

The reporting of colorectal cancer is facilitated by the provision of a checklist giving the features required for good patient care. However, the practicalities of applying such a checklist may not be straightforward. Familiar examples include finding the prescribed number of lymph nodes, distinguishing mesenteric tumor deposits from replaced lymph nodes, and deciding if a cluster of malignant cells in a lymph node sinus counts as metastasis. Checklists have traditionally focused on prognostic factors and, particularly, tumor stage. It is becoming increasingly clear that additional factors, whether morphological or molecular, will be needed for future clinical management. It is also evident that prognosis is strongly influenced by the surgical technique used, most notably by the introduction of total mesorectal excision in the case of rectal cancer. Adjuvant therapy is playing an increasingly important role in the management of colorectal cancer, and it is inevitable that morphological and molecular markers will be used to predict responses to the expanding range of therapeutic modalities. Neoadjuvant or preoperative radiotherapy is being offered to patients with advanced rectal cancer and can greatly modify the pathologic findings in operative specimens. For all the preceding reasons, the work of diagnostic pathologists has become increasingly complex and demanding. The 6th edition of the TNM classification fails to meet many of the challenges posed by the realities of modern cancer management. In fact, by changing the rules for staging without strong justification and introducing diagnostic criteria that are unhelpful and lack a good evidence base, there is a real danger that the community of pathologists will fail to engage with reporting recommendations in a standardized manner and that the quality of reporting will decline.

Preoperative staging of rectal cancer with MR Imaging: correlation with surgical and histopathologic findings

Rectal cancer is a common malignancy that continues to have a highly variable outcome, with local pelvic recurrence after surgical resection usually leading to incurable disease. The success of tumor excision depends largely upon accurate tumor staging and appropriate surgical technique, although the results of recent surgical trials indicate that evaluation of the involvement of the mesorectal fat and mesorectal fascia is even more important than T staging for treatment planning. Magnetic resonance (MR) imaging is increasingly being used to evaluate tumor resectability in patients with rectal cancer and to determine which patients can be treated with surgery alone and which will require radiation therapy to promote tumor regression. High-spatial-resolution MR imaging has proved useful in clarifying the relationship between a tumor and the mesorectal fascia, which represents the circumferential resection margin at total mesorectal excision. Phased-array surface coil MR imaging in particular plays a vital role in the therapeutic management of rectal cancer. At present, phased-array MR imaging best fulfills the clinical requirements for preoperative staging of rectal cancer. However, preoperative evaluation of the other prognostic factor, nodal status, is still problematic, and further studies will be needed to better define the role of MR imaging in this context.

Rectal carcinoma: high-spatial-resolution MR imaging and T2 quantification in rectal cancer specimens

PURPOSE

To prospectively compare high-spatial-resolution T1-weighted, T2-weighted, and intermediate-weighted spectral fat-saturated magnetic resonance (MR) imaging for the differentiation of tumor from fibrosis and for delineation of rectal wall layers in rectal cancer specimens.

MATERIALS AND METHODS

The local ethics committee approved the protocol, and written informed consent was obtained from each patient. Thin-section high-spatial-resolution MR imaging was performed in specimens obtained from 23 patients (16 men, seven women; median age, 64 years; age range, 39-84 years) immediately after resection. Seven patients underwent neoadjuvant treatment. T1-weighted spin-echo, T2-weighted fast spin-echo, and intermediate-weighted spectral fat-saturated MR images were obtained in the transverse plane. Differences in signal intensity between tumor and fibrosis and between tumor and rectal wall layers were evaluated by using visual scoring and measurements of T2 relaxation time. Statistical differences were evaluated by using the Wilcoxon signed rank test and a mixed-model regression analysis. All images were compared with whole-mount histopathologic slices (n = 86).

RESULTS

T2-weighted MR images provided the best differentiation between tumor and fibrosis (P < .001). Mean visual signal intensity scores were -1.8 for T2-weighted MR images, -1.4 for intermediate-weighted spectral fat-saturated MR images, and -0.2 for T1-weighted MR images. T2 relaxation times were 97 msec +/- 4.6 for tumor and 70 msec +/- 3.8 for fibrosis (P < .001). Substantial overlap was noted between the tumor and the circular layer of the muscularis propria (97 msec +/- 2.1), and less overlap was noted between the tumor and the longitudinal layer of the muscularis propria (88 msec +/- 1.6).

CONCLUSION

T2-weighted MR imaging provides superior delineation of rectal wall layers and better differentiation of tumor from fibrosis in rectal cancer specimens compared with T1-weighted MR imaging and intermediate-weighted spectral fat-saturated MR imaging by using thin-section high-spatial-resolution sequences.

Thin section MRI in multidisciplinary pre-operative decision making for patients with rectal cancer

High spatial resolution MRI of the rectum is an accurate method of staging rectal cancer. The technique requires attention to detail so that correct planes and scan parameters are used to obtain the best images. A detailed understanding of the pathological features of these tumours is required for image interpretation so that prognostic information beyond the basic T and N staging of the tumour can be obtained. Use of standardized criteria for reporting is reproducible in the multicentre setting and pre-operative multidisciplinary discussion of the MRI features increases the number of operations performed with tumour-free resection margins.

Effectiveness of preoperative staging in rectal cancer: digital rectal examination, endoluminal ultrasound or magnetic resonance imaging?

In rectal cancer, preoperative staging should identify early tumours suitable for treatment by surgery alone and locally advanced tumours that require therapy to induce tumour regression from the potential resection margin. Currently, local staging can be performed by digital rectal examination (DRE), endoluminal ultrasound (EUS) or magnetic resonance imaging (MRI). Each staging method was compared for clinical benefit and cost-effectiveness. The accuracy of high-resolution MRI, DRE and EUS in identifying favourable, unfavourable and locally advanced rectal carcinomas in 98 patients undergoing total mesorectal excision was compared prospectively against the resection specimen pathological as the gold standard. Agreement between each staging modality with pathology assessment of tumour favourability was calculated with the chance-corrected agreement given as the kappa statistic, based on marginal homogenised data. Differences in effectiveness of the staging modalities were compared with differences in costs of the staging modalities to generate cost effectiveness ratios. Agreement between staging and histologic assessment of tumour favourability was 94% for MRI (κ=0.81, s.e.=0.05; κ_W=0.83), compared with very poor agreements of 65% for DRE (κ=0.08, s.e.=0.068, κ_W=0.16) and 69% for EUS (κ=0.17, s.e.=0.065, κ_W=0.17). The resource benefits resulting from the use of MRI rather than DRE was £67164 and £92244 when MRI was used rather than EUS. Magnetic resonance imaging dominated both DRE and EUS on cost and clinical effectiveness by selecting appropriate patients for neoadjuvant therapy and justifies its use for local staging of rectal cancer patients.

Rectal cancer: local staging and assessment of lymph node involvement with endoluminal US, CT, and MR imaging--a meta-analysis

PURPOSE

To perform a meta-analysis to compare endoluminal ultrasonography (US), computed tomography (CT), and magnetic resonance (MR) imaging in rectal cancer staging.

MATERIALS AND METHODS

Relevant articles published between 1985 and 2002 were included if more than 20 patients were studied, histopathologic findings were the reference standard, and data were presented for 2 x 2 tables; articles were excluded if data were reported elsewhere in more detail. Two reviewers independently extracted data on study characteristics and results. Bivariate random-effects approach was used to obtain summary estimates of sensitivity and specificity for invasion of muscularis propria, perirectal tissue, and adjacent organs and for lymph node involvement. Summary receiver operating characteristic (ROC) curves were fitted for perirectal tissue invasion and lymph node involvement.

RESULTS

Ninety articles fulfilled all inclusion criteria. For muscularis propria invasion, US and MR imaging had similar sensitivities; specificity of US (86% [95% confidence interval [CI]: 80, 90]) was significantly higher than that of MR imaging (69% [95% CI: 52, 82]) (P =.02). For perirectal tissue invasion, sensitivity of US (90% [95% CI: 88, 92]) was significantly higher than that of CT (79% [95% CI: 74, 84]) (P <.001) and MR imaging (82% [95% CI: 74, 87]) (P =.003); specificities were comparable. For adjacent organ invasion and lymph node involvement, estimates for US, CT, and MR imaging were comparable. Summary ROC curve for US of perirectal tissue invasion showed better diagnostic accuracy than that of CT and MR imaging. Summary ROC curves for lymph node involvement showed no differences in accuracy.

CONCLUSION

For local invasion, endoluminal US was most accurate and can be helpful in screening patients for available therapeutic strategies.

In vitro investigation of detectability of colorectal lymph nodes and diagnosis of lymph node metastasis in colorectal cancer using B-mode sonography

PURPOSE

The aim of this in vitro study was to assess the feasibility of using high-frequency sonography to identify colorectal lymph nodes and to diagnose colorectal lymph node metastasis.

METHODS

In part 1 of this study, resected colorectal tissues from 13 patients with colorectal cancer were scanned in a water bath using B-mode sonography performed at high frequency (10 MHz) to identify lymph nodes. The colorectal tissues were then carefully dissected to remove all lymph nodes. Detectability was calculated as the ratio of the number of sonographically detected nodes to the total number of histopathologically confirmed nodes. Student's t test was performed to compare sizes between these groups; a p value of less than 0.05 was considered significant. In part 2, 4 features of lymph nodes identified on B-mode sonography--size, shape, border, and echogenicity--and their combinations were evaluated for their ability to diagnose lymph node metastasis. Discriminant and receiver operating characteristic curve analyses were performed.

RESULTS

In part 1, B-mode sonography performed in vitro detected 79 (48%) of the 165 histopathologically identified lymph nodes and 34 (87%) of the 39 histopathologically identified metastatic nodes. The mean size, or mean longest axis (+/- standard deviation), of the sonographically detected nodes (6.4 +/- 2.9 mm) was significantly larger than that of undetected nodes (3.6 +/- 1.7 mm; p < 0.01). In part 2, the most effective feature distinguishing metastatic from nonmetastatic lymph nodes was echogenicity, followed by size, shape, and border. However, a combination of at least 2 features (eg, echogenicity and size) provided better distinction of nodes than did any 1 feature. In the receiver operating characteristic curve of the 4-feature combination, an increase in sensitivity is accompanied by a decrease in specificity: at a sensitivity of 100%, specificities decreased to 60% or less. However, even with the optimal combination of features, the sensitivity and specificity did not both reach 85% at any operating point.

CONCLUSIONS

The results of this node-by-node in vitro study show the current limitations and potential of sonography for assessing colorectal lymph nodes. High-frequency sonography may be insufficient for identifying lymph node metastasis in colorectal cancer.

Preoperative assessment of prognostic factors in rectal cancer using high-resolution magnetic resonance imaging

BACKGROUND

The aim was to determine the accuracy of preoperative magnetic resonance imaging (MRI) in the evaluation of pathological prognostic factors that influence local recurrence and survival in rectal cancer.

METHODS

Ninety-eight patients undergoing total mesorectal excision for biopsy-proven rectal cancer were assessed prospectively using high-resolution MRI for tumour (T) and nodal (N) staging using the tumour node metastasis classification, depth of extramural tumour spread, the presence or absence of extramural venous invasion, a threatened circumferential resection margin and serosal involvement at or above the peritoneal reflection. Preoperative magnetic resonance assessment of these prognostic factors was compared with histopathological findings in carefully matched whole-mount sections of the resection specimen.

RESULTS

There was 94 per cent weighted agreement (weighted kappa = 0.67) between MRI and pathology assessment of T stage. Agreement between MRI and histological assessment of nodal status was 85 per cent (kappa = 0.68). Although involvement of small veins by tumour was not discernible using MRI, large (calibre greater than 3 mm) extramural venous invasion was identified correctly in 15 of 18 patients (kappa = 0.64). MRI predicted circumferential resection margin involvement with 92 per cent agreement (kappa = 0.81). Seven of nine patients with peritoneal perforation by tumour (stage T4) were identified correctly using MRI.

CONCLUSION

High-resolution MRI of the rectum allows preoperative identification of important surgical and pathological prognostic risk factors. This may allow both better selection and assessment of patients undergoing preoperative therapy.

Rectal excision with coloanal anastomosis for superficial distal third rectal cancer: survival and local recurrence

OBJECTIVE

Appropriate surgical treatment of distal third rectal cancer limited to bowel wall (i.e. T1 or T2) in medically operable patients is controversial. Transanal excision can deprive some patients of accurate pathological staging, prognosis and cure. In contrast abdominoperineal resection has considerable practical and psychosocial problems largely related to a permanent colostomy. We hypothesize that superficial distal rectal tumours can be effectively treated with rectal excision and coloanal anastomosis.

SUBJECTS AND METHODS

Prospective oncological study of 80 patients with distal third superficial rectal carcinomas treated by complete rectal excision with coloananl anastomosis from December 1977 to January 1993 was carried out. The resected specimens were examined for depth of spread and number of histologically positive nodes. The actuarial local recurrence and survival rates for superficial node-negative and node-positive tumours were analysed independently.

RESULTS

Seventy-eight patients had complete postoperative assessment. Thirty-one percent had received low-dose preoperative neo-adjuvant radiotherapy (3500 rads). Mean follow-up time in all patients was 70 months on average. The lymph node involvement rate for T1 and T2 tumours was 12.5 and 15.6%, respectively. The local recurrence rates for patients with (T1/T2) N0 and (T1/T2) N1 were 1.5 and 16.7%, respectively, and the five year actuarial survival rates were 96.6 and 90%, respectively. The overall local recurrence was 3.8% with five-year actuarial survival of 95.8%.

CONCLUSIONS

Lymph node involvement in superficial tumours is not rare. Rectal excision with coloanal anastomosis results in a high cure rate especially for node-positive superficial tumours. This treatment strategy avoids the psychological trauma of colostomy following abdominoperineal resection and the potential risk of undertreatment by local excision.

Preoperative staging of rectal carcinoma

BACKGROUND

The development of treatment modalities for rectal cancer, including local excision, total mesorectal excision and preoperative radiotherapy, has increased the importance of accurate preoperative staging to allow the optimum treatment to be selected.

METHODS

A literature review was undertaken of methods of preoperative staging of rectal carcinoma and the evidence for each was evaluated critically.

RESULTS

Clinical assessment of rectal carcinoma may give an indication of fixity but is not accurate for staging. Endoanal ultrasonography, computed tomography (CT), magnetic resonance imaging (MRI), radioimmunoscintigraphy and positron emission tomography have all been used for staging. The extent of tumour spread through the bowel wall (T stage) is most accurately assessed by endoanal ultrasonography, although this technique is poor at assessing tumour extension into adjacent organs for which both CT and MRI are more accurate. No method accurately determines lymph node involvement, but endoanal ultrasonography is the best available. Liver metastases may be assessed by abdominal ultrasonography, CT, MRI and CT portography (with increasing sensitivity and cost in that order).

CONCLUSION

Endoanal ultrasonography is the most effective method of local tumour staging, with the addition of either CT or MRI if adjacent organ involvement is suspected. Abdominal ultrasonography or CT is recommended for routine preoperative assessment of the liver.

Pathologic determinants of survival associated with colorectal cancer with lymph node metastases. A multivariate analysis of 579 patients

BACKGROUND

Patients with colorectal carcinoma found to have regional lymph node metastases after curative resection form a large and prognostically diverse group. This study aims to determine which pathology variables have independent prognostic effects.

METHODS

The data from the 579 patients used in this analysis were collected prospectively during a period of 21.5 years. The patients were from one institution, and the pathologic documentation was standardized. Patient follow-up ranged between 6 months and 21.5 years. Survival analysis was by the Kaplan-Meier method. Multivariate models were examined using Cox proportional hazards regression.

RESULTS

On univariate analysis, eight pathology variables had a significant association with survival. Six of these variables showed significant independent effects on survival on multivariate analysis. In diminishing potency, these variables were: apical lymph node involvement; spread involving a free serosal surface; invasion beyond the muscularis propria; location in the rectum; venous invasion; high tumor grade. Significant independent effects also were shown for patient age and gender. The number of involved lymph nodes added no significant independent prognostic information.

CONCLUSION

Six pathology variables have been identified that act independently in determining the survival of patients with colorectal carcinoma and lymph node metastases. The most potent of these variables, apical lymph node involvement, was used by Dukes to subclassify Stage C tumors. Another variable, direct spread beyond the muscularis propria, defines the Astler-Coller subclassification. It is recommended that all six independent variables be included in any future protocol for stratifying this prognostically diverse group of patients.

Lateral lymph node dissection for rectal carcinoma below the peritoneal reflection

Lateral lymph node dissection has been advocated for advanced low rectal tumours. However, its benefit is debatable because of the possibility of postoperative bladder and sexual impairment. To assess the role of lateral lymph node dissection 95 patients who underwent the procedure between 1981 and 1991 were reviewed and compared with 83 who had resection of rectal cancer without lateral node dissection. Only ten (11 per cent) of the 95 patients had lateral lymph node involvement; all had Dukes' C tumours. Lymphovascular invasion was present in 50.6 per cent of all patients and neural invasion in 27 per cent of 65 examined specimens. Local recurrence, distant metastasis and overall 5-year survival rates were 7, 9 and 76 per cent respectively in patients undergoing extended lymphadenectomy and 16, 7 and 72 per cent respectively in those who had resection alone. There were no statistically significant differences in survival between the two groups for any Dukes' stage. Recurrence, metastasis and survival were related more to venous or neural invasion and tumour spread than to node dissection. These results demonstrate that patients with Dukes' A tumours do not benefit from lateral lymph node dissection, and that local recurrence rates in those with Dukes' B and C lesions are not significantly decreased. It is concluded that extended lymphadenectomy is unlikely to provide significant benefit to patients with low rectal cancer.

Lymph node metastases in early rectal cancer

Local excision of early rectal tumours is an attractive proposition, avoiding the morbidity and mortality of major resection and possible permanent stoma. This study was designed to investigate the incidence of lymph node metastases associated with tumours that are locally confined to the bowel wall. A total of 454 rectal excision specimens were reviewed. Twenty-two (20 per cent) of 109 patients with tumours locally confined to the bowel wall had metastases in local lymph nodes, although 14 of these had only one or two involved nodes. Three of 27 patients with tumours that did not penetrate through the submucosa had lymph node metastases. Less well differentiated tumours were more likely to have metastasized but there was no significant difference in the height or size of tumours or in the depth of invasion between patients with or without lymph node metastases.

Malignant colorectal polyps: venous invasion and successful treatment by endoscopic polypectomy

We reviewed the pathology of 81 malignant colorectal polyps in 80 patients treated by endoscopic polypectomy and assessed the importance of carcinomatous invasion of veins in the stalk (submucosa). All the patients were followed up for at least five years. Venous invasion was present in 30 of the polyps (37%). The histological features of lymphatic invasion were considered too subjective to be of value. Most of the tumours were well or moderately differentiated adenocarcinomas, one was poorly differentiated, and one was a signet ring cell carcinoma. Seventy one patients were treated by polypectomy alone, and 58 of these were alive and well five years later, with no evidence of recurrence. Nine died of unrelated causes within five years, but four died of carcinomatosis: one with recurrent tumour, one with a possible metachronous caecal cancer, and in two patients there was late development of malignancy of uncertain nature. The remaining nine patients underwent surgical resection after initial endoscopic polypectomy because of incompleteness of excision, poor differentiation of the tumour, or a decision by the surgeon. Tumour was not present in the resection specimens apart from a single lymph node deposit in the patient with signet ring cell carcinoma. These nine patients were alive and well without evidence of recurrence five years later. The results reemphasize the necessity of good cooperation between endoscopist and pathologist, meticulous laboratory technique, strict histopathological criteria including examination of resection margins and degree of differentiation of the tumour, and regular endoscopic follow up. Endoscopic polypectomy of pedunculated and sessile malignant polyps is adequate treatment if the lesion can be removed in one piece, the tumour is well or moderately differentiated, and local excision is judged complete by endoscopic and histological criteria. Patients with histologically incompletely excised polyps, containing well or moderately differentiated carcinoma, can be safely managed by conservative treatment provided the endoscopist is certain there is no residual tumour. Venous invasion by tumour is a common finding in malignant colorectal polyps and seems to have no prognostic importance.

Systematic computer-aided search of optimal staging system for colorectal cancer

Two hundred and ninety-eight patients with curatively resected colorectal cancer were classified into 12 categories according to the depth of tumour penetration (T1-T4), and lymph node status (N0-N2). Using a computer, these categories were grouped into 2-12 stages in every possible combination, so a total of 146,975 logical classifications were generated. The optimal model was selected for each group of classifications with equal stage number, thus giving the greatest prognostic information on 5-year survival according to the Akaike criterion. The results showed that (1) 13% of the total classifications, including 85% of the 3-stage classifications, were better than the Dukes system in predicting our patients' outcomes; (2) the T-level was a stage-determinant even more important than the N-level; and (3) major changes in prognosis occurred at more advanced stages than the classical "turning points". We conclude that in order to find an optimal staging of cancer, systematic computer-aided search through all the possible classifications is necessary, using the appropriate database.