Patterns of recurrence in adenocarcinoma of the rectum and rectosigmoid treated with surgery alone: implications in treatment planning with adjuvant radiation therapy

Locally Recurrent Rectal Cancer According to a Standardized MRI Classification System: A Systematic Review of the Literature

(1) Background: The classification of locally recurrent rectal cancer (LRRC) is not currently standardized. The aim of this review was to evaluate pelvic LRRC according to the Beyond TME (BTME) classification system and to consider commonly associated primary tumour characteristics. (2) Methods: A systematic review of the literature prior to April 2020 was performed through electronic searches of the Science Citation Index Expanded, EMBASE, MEDLINE, and CENTRAL databases. The primary outcome was to assess the location and frequency of previously classified pelvic LRRC and translate this information into the BTME system. Secondary outcomes were assessing primary tumour characteristics. (3) Results: A total of 58 eligible studies classified 4558 sites of LRRC, most commonly found in the central compartment (18%), following anterior resection (44%), in patients with an 'advanced' primary tumour (63%) and following neoadjuvant radiotherapy (29%). Most patients also classified had a low rectal primary tumour. The lymph node status of the primary tumour leading to LRRC was comparable, with 52% node positive versus 48% node negative tumours. (4) Conclusions: This review evaluates the largest number of LRRCs to date using a single classification system. It has also highlighted the need for standardized reporting in order to optimise perioperative treatment planning.

Systematic review of classification systems for locally recurrent rectal cancer

Background

Classification of pelvic local recurrence (LR) after surgery for primary rectal cancer is not currently standardized and optimal imaging is required to categorize anatomical site and plan treatment in patients with LR. The aim of this review was to evaluate the systems used to classify locally recurrent rectal cancer (LRRC) and the relevant published outcomes.

Methods

A systematic review of the literature prior to April 2020 was performed through electronic searches of the Science Citation Index Expanded, EMBASE, MEDLINE and CENTRAL databases. The primary outcome was to review the classifications currently in use; the secondary outcome was the extraction of relevant information provided by these classification systems including prognosis, anatomy and prediction of R0 after surgery.

Results

A total of 21 out of 58 eligible studies, classifying LR in 2086 patients, were reviewed. Studies used at least one of the following eight classification systems proposed by institutions or institutional groups (Mayo Clinic, Memorial Sloan-Kettering – original and modified, Royal Marsden and Leeds) or authors (Yamada, Hruby and Kusters). Negative survival outcomes were associated with increased pelvic fixity, associated symptoms of LR, lateral compared with central LR and involvement of three or more pelvic compartments. A total of seven studies used MRI with specifically defined anatomical compartments to classify LR.

Conclusion

This review highlights the various imaging systems in use to classify LRRC and some of the prognostic indicators for survival and oncological clearance based on these systems. Implementation of an agreed classification system to document pelvic LR consistently should provide more detailed information on anatomical site of recurrence, burden of disease and standards for comparative outcome assessment.

Determining whether postoperative chemoradiotherapy is required in patients with pathologic T3N0 rectal cancer with negative resection margin

PURPOSE

This study aimed to identify the risk factors for locoregional recurrence (LR) and determine possible candidates for postoperative concurrent chemoradiotherapy (CCRT) in pathologic T3N0 (pT3N0) rectal cancer patients with a negative resection margin after total mesorectal excision (TME).

METHOD

Data from 365 patients who had pT3N0 rectal cancer between 2003 and 2012 in the Samsung Medical Center were reviewed. All patients underwent upfront surgery without preoperative treatment. Postoperative management involved either no adjuvant therapy (n = 122), chemotherapy alone (n = 100), or CCRT (n = 143).

RESULTS

The median follow-up duration was 71 months. The 5-year overall survival, disease-free survival, and LR-free survival (LRFS) rates were 95.9%, 86.9%, and 96.3%, respectively. When comparing the three groups (surgery alone [n = 122], chemotherapy alone [n = 100], and CCRT [n = 143]), there was no significant difference in LRFS among them (94.0%, 93.4%, and 99.2%, respectively; p = 0.20). However, when patients were stratified by risk factors (distance from anal verge ≤ 5 cm and distal resection margin [DRM] ≤ 2 cm), the 5-year LRFS improved by more than 10% by adding CCRT (98.9% with CCRT vs. 87.4% without CCRT, p = 0.006) in those with more than one risk factor. Postoperative CCRT did not affect the 5-year LRFS (100% with CCRT vs. 99.0% without CCRT, p = 0.66) in patients with no risk factors.

CONCLUSION

Postoperative CCRT significantly decreased LR in patients with pT3N0 rectal cancer with a negative resection margin but having a distance from the anal verge ≤ 5 cm or DRM ≤ 2 cm.

Raltitrexed and Radiotherapy as Adjuvant Treatment for Stage II-III Rectal Cancer: A Feasibility Study

Aims and Background

Adjuvant 5-FU chemotherapy plus radiotherapy represents the standard treatment for radically resected rectal cancer at high risk of relapse according to the NIH Consensus Conference. The therapeutic gain was obtained with a high rate of severe treatment-related toxicity and a sub-optimal patient compliance with this regimen. Raltitrexed is a specific thymidylate synthase inhibitor with a convenient administration schedule, acceptable toxicity and radiosensitizing properties, as the published phase I trials in combination with radiotherapy have shown. The aim of this prospective multicenter phase II study was to evaluate the feasibility, gastrointestinal and hematological acute toxicity of raltitrexed in combination with radiotherapy in rectal cancer patients.

Methods

From September 2000 to June 2004, 50 patients with radically resected stage II-III rectal adenocarcinoma were treated. All patients were evaluable for compliance and acute toxicity. Within 45-60 days of surgery, each patient underwent concomitant adjuvant radiochemotherapy. Radiotherapy was administered to the pelvis (plus perineum after abdominoperineal resection) with photon beam energy exceeding 5 MV, 3-4 fields, 45 Gy/25 fractions/5 weeks plus a boost delivered to the site of resected disease with 3-4 fields, 9 Gy/5 fractions/1 week to a total dose of 54 Gy. The boost dose was administered after complete exclusion of the small bowel from the treatment volumes; if this was not possible a total dose of 50.4 Gy was given. Raltitrexed was administered intravenously at a dose of 3 mg/m2 as a bolus injection on days 1 and 22 of radiotherapy one hour before treatment, for a total of two cycles. Each patient underwent weekly clinical evaluation and laboratory tests. Toxicity was assessed by the WHO scale.

Results

Forty-five (90%) patients completed the established treatment. Acute severe toxicity included grade III proctitis in 4/50 (8%), grade III-IV diarrhea in 4/50 (8%), grade III perineal dermatitis in 4/50 (8%) and grade III leukopenia in 2/50 (4%) patients; five patients (10%) experienced a transient grade III increase in their liver biochemistry values.

Conclusions

Our data related to acute toxicity and patient compliance proved the feasibility of this adjuvant radiochemotherapy treatment. A longer follow-up is necessary to evaluate the effectiveness of this new regimen in terms of disease-free and overall survival.

Preoperative radiotherapy and curative surgery for the management of localised rectal carcinoma

BACKGROUND

This is an update of the original review published in 2007.Carcinoma of the rectum is a common malignancy, especially in high income countries. Local recurrence may occur after surgery alone. Preoperative radiotherapy (PRT) has the potential to reduce the risk of local recurrence and improve outcomes in rectal cancer.

OBJECTIVES

To determine the effect of preoperative radiotherapy for people with localised resectable rectal cancer compared to surgery alone.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (the Cochrane Library; Issue 5, 2018) (4 June 2018), MEDLINE (Ovid) (1950 to 4 June 2018), and Embase (Ovid) (1974 to 4 June 2018). We also searched ClinicalTrials.gov and the WHO International Clinical Trials Registry Platform (ICTRP) for relevant ongoing trials (4 June 2018).

SELECTION CRITERIA

We included randomised controlled trials comparing PRT and surgery with surgery alone for people with localised advanced rectal cancer planned for radical surgery. We excluded trials that did not use contemporary radiotherapy techniques (with more than two fields to the pelvis).

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed the 'Risk of bias' domains for each included trial, and extracted data. For time-to-event data, we calculated the Peto odds ratio (Peto OR) and variances, and for dichotomous data we calculated risk ratios (RR) using the random-effects method. Potential sources of heterogeneity hypothesised a priori included study quality, staging, and the use of total mesorectal excision (TME) surgery.

MAIN RESULTS

We included four trials with a total of 4663 participants. All four trials reported short PRT courses, with three trials using 25 Gy in five fractions, and one trial using 20 Gy in four fractions. Only one study specifically required TME surgery for inclusion, whereas in another study 90% of participants received TME surgery.Preoperative radiotherapy probably reduces overall mortality at 4 to 12 years' follow-up (4 trials, 4663 participants; Peto OR 0.90, 95% CI 0.83 to 0.98; moderate-quality evidence). For every 1000 people who undergo surgery alone, 454 would die compared with 45 fewer (the true effect may lie between 77 fewer to 9 fewer) in the PRT group. There was some evidence from subgroup analyses that in trials using TME no or little effect of PRT on survival (P = 0.03 for the difference between subgroups).Preoperative radiotherapy may have little or no effect in reducing cause-specific mortality for rectal cancer (2 trials, 2145 participants; Peto OR 0.89, 95% CI 0.77 to 1.03; low-quality evidence).We found moderate-quality evidence that PRT reduces local recurrence (4 trials, 4663 participants; Peto OR 0.48, 95% CI 0.40 to 0.57). In absolute terms, 161 out of 1000 patients receiving surgery alone would experience local recurrence compared with 83 fewer with PRT. The results were consistent in TME and non-TME studies.There may be little or no difference in curative resection (4 trials, 4673 participants; RR 1.00, 95% CI 0.97 to 1.02; low-quality evidence) or in the need for sphincter-sparing surgery (3 trials, 4379 participants; RR 0.99, 95% CI 0.94 to 1.04; I² = 0%; low-quality evidence) between PRT and surgery alone.Low-quality evidence suggests that PRT may increase the risk of sepsis from 13% to 16% (2 trials, 2698 participants; RR 1.25, 95% CI 1.04 to 1.52) and surgical complications from 25% to 30% (2 trials, 2698 participants; RR 1.20, 95% CI 1.01 to 1.42) compared to surgery alone.Two trials evaluated quality of life using different scales. Both studies concluded that sexual dysfunction occurred more in the PRT group. Mixed results were found for faecal incontinence, and irradiated participants tended to resume work later than non-irradiated participants between 6 and 12 months, but this effect had attenuated after 18 months (low-quality evidence).

AUTHORS' CONCLUSIONS

We found moderate-quality evidence that PRT reduces overall mortality. Subgroup analysis did not confirm this effect in people undergoing TME surgery. We found consistent evidence that PRT reduces local recurrence. Risk of sepsis and postsurgical complications may be higher with PRT.The main limitation of the findings of the present review concerns their applicability. The included trials only assessed short-course radiotherapy and did not use chemotherapy, which is widely used in the contemporary management of rectal cancer disease. The differences between the trials regarding the criteria used to define rectal cancer, staging, radiotherapy delivered, the time between radiotherapy and surgery, and the use of adjuvant or postoperative therapy did not appear to influence the size of effect across the studies.Future trials should focus on identifying participants that are most likely to benefit from PRT especially in terms of improving local control, sphincter preservation, and overall survival while reducing acute and late toxicities (especially rectal and sexual function), as well as determining the effect of radiotherapy when chemotherapy is used and the optimal timing of surgery following radiotherapy.

Adjuvant Radiochemotherapy in High-Risk Rectal Cancer Results of a Prospective Non-Randomized Study

Aims and Background

In 1990 the National Institutes of Health Consensus Conference recommended adjuvant combined therapy for patients with radically resected rectal cancer at high risk for relapse (ie, stage II-III). The purpose of our prospective non-randomized study was to verify the feasibility and effectiveness of postoperative radiochemotherapy in terms of improvement in disease-free and overall survival in this patient subgroup.

Study design

From January 1990 to October 1998, 191 consecutive patients with radically resected stage II-III rectal cancer were treated. A total of 159 patients with a 24-month follow-up were assessable for toxicity and survival. Anterior resection was performed in 129 (81%) and abdomino-perineal resection in 30 (19%) patients. Fifty-four (34%) stage II and 105 (66%) stage III patients entered the study. Within 45-60 days of surgery, all patients received 5-fluorouracil chemotherapy at the dose of 500 mg/m2 as an iv bolus on days 1-5, every 4 weeks, for 6 cycles. Chemotherapy cycles III and IV were administered at the same daily dose on radiotherapy days 1-3 and 29-31. Radiotherapy consisted of 45 Gy/25 fractions plus a boost dose of 5.4 Gy.

Results

After a median follow-up of 57 months (range, 25-123), overall recurrent disease was reported in 58 (36%) patients: local, systemic, and both local and systemic relapses in 12 (8%), 37 (23%) and 9 (6%) cases, respectively. According to local extension, recurrence rates were 15% and 48% in stage II and III, respectively. Five-year overall and disease-free survival were 71% and 66%, respectively. Overall survival was 87% in stage II and 62% in stage III patients, and disease-free survival was 84% and 56% in stage II and III disease, respectively. According to univariate and multivariate analyses, significant prognostic factors for better tumor control were: stage (II vs III, P <0.001), the number of involved nodes (≤3 vs >3, P <0.0001), and no extracapsular node invasion (P <0.0001). The recommended dose of the combined radiochemotherapy regimen was generally well tolerated. The incidence of any ≥ grade 3 acute toxicity (according to the WHO scale) was 13% diarrhea, 11% proctitis, 5% perineal dermatitis and 4% myelosuppression. Four (3%) patients had radiotherapy-related severe late toxicity which required surgery.

Conclusions

The study provided recurrence rates and survival similar to other adjuvant radiochemotherapy regimens published in the literature. However, in view of the low 5-year survival rate recorded in stage III patients, a different approach should be investigated.

Ninety percent of the adverse outcomes occur in 10% of patients: can we identify the populations at high risk of developing peritoneal metastases after curative surgery for colorectal cancer?

BACKGROUND

Peritoneal metastases (PM) occur in 3.4-6.3% after curative surgery for non-metastatic colorectal cancer. Systematic "2nd look" surgery helps overcoming the diagnostic problem but can be only proposed to selected patients. The aim of this study was to update the knowledge on risk factors of developing PM after curative surgery for colorectal cancer.

METHODS

A systematic review of the literature published between 2011 and 2016 was made, searching for all clinical studies reporting the incidence of recurrent PM after curative surgery for colorectal cancer and factors associated with the primary tumour that were likely to influence this recurrence rate.

RESULTS

Seven new clinical studies were considered informative for risk factors and added to the 16 reviewed in 2013. Even if the level of evidence was low, data suggested rates of recurrent PM at 1 year between 54% and 71% after completely resected synchronous PM, between 62% and 71% after resection of isolated synchronous ovarian metastases, of 27% after surgery for a perforated primary tumour, of 16% after surgery for a pT4 tumour, and between 11% and 36% after surgery for a mucinous histological subtype. No new risk factor was identified.

CONCLUSIONS

Evidence regarding the incidence of recurrent PM after curative surgery for colorectal cancer is poor. Situations at higher risk of recurrent PM are synchronous PM, synchronous isolated ovarian metastases, perforated primary tumour with serosa invasion and mucinous histological subtype.

Neoadjuvant Treatment for Locally Advanced Rectal Cancer: New Concepts in Clinical Trial Design

OPINION STATEMENT

Treatment for locally advanced rectal cancer has evolved from surgery alone to surgery plus adjuvant therapy. Preoperative 5-fluorouracil- or capecitabine-based chemoradiation with standard fractionated radiation, surgery utilizing total mesorectal excision, and further chemotherapy has become the standard of care in the USA. Preoperative adjuvant chemoradiation treatment sequencing has allowed for decreased toxicity, more sphincter-sparing surgery, and improved local control rates as compared to delivering the chemoradiation postoperatively. Yet, given the heterogeneity of locally advanced disease, some patients may be over-treated with this approach, leading to unnecessary toxicity and costs, while others may have a propensity to develop distant metastases and may benefit from intensified therapy. Therefore, the trend in modern clinical trial design has been to individualize therapy. As such, current studies are examining shortening the duration of radiation, omitting preoperative chemoradiation in patients who have a robust response to induction chemotherapy alone, omitting or delaying surgery in patients who have a clinical complete response to preoperative chemoradiation, and completing all of the adjuvant treatment prior to surgery.

Trends with neoadjuvant radiotherapy and clinical staging for those with rectal malignancies

AIM

To see how patterns of care changed over time, and how institution type effected these decisions.

METHODS

A retrospective analysis was performed using the National Cancer Database, looking at all patients that were diagnosed with rectal cancer from 1998 to 2011. We tested differences in rates of treatment and stage migration using χ² tests and logistic regression models.

RESULTS

A review of ninety thousand five hundred and ninety four subjects underwent multimodality therapy for cancer of the rectum. Staging and response to treatment varied greatly between centers. Forty-six percent of the time staging was missing in academic practices, vs fifty-four percent of the time in community centers (P < 0.001). As a result, twenty-percent were down-staged and eight percent up-staged in academia, whereas only fifteen percent were down-staged and 8% up-staged in community practices (P < 0.001). Forty-two percent of individuals underwent radiation before surgery in 1998. Within two years this increased to fifty-three percent. This increased to eighty-six percent by 2011 (P < 0.001). Institution specific treatment varied greatly. Fifty-one percent received therapy before surgery in academic centers in 1998. Thirty-nine percent followed this pattern in the same year in the community (P < 0.001). By 2011, ninety-one percent received radiation before their procedure in academic centers, vs eighty-four percent in the community (P < 0.001). Rates of adoption were better in academia, although an increase was seen in both center types.

CONCLUSION

From the study dates of 1998 to 2011, preoperative treatment with radiation has been on the rise. There is certainly an increased rate of use of radiation in academia, however, this trend is also seen in the community. Practice patterns have evolved over time, although rates of assigning clinical stage are grossly underreported prior to initiation of preoperative therapy.

Organ preservation in rectal cancer - Challenges and future strategies

Neoadjuvant radiochemotherapy with subsequent total mesorectal excision is the standard of care for locally advanced rectal cancer. While this multimodal strategy has decreased local recurrences rates below 5%, long-term morbidities are considerable in terms of urinary, sexual or bowel functioning. At the same time approximately 10–20% of patients have no evidence of residual tumour in their surgical specimen. Pioneering studies from Brazil have suggested that surgery can safely be omitted in carefully selected patients with a clinical complete response after radiochemotherapy. Although confirmatory studies showed similar results, challenges in terms of optimizing radiochemotherapy for organ-preservation, appropriate selection of patients for non-operative management and the safety of this approach remain. The present review will summarize the current data on organ-preservation in rectal cancer and discuss the challenges that need to be addressed in future trials.

Pharmacokinetic problems in peritoneal drug administration: an update after 20 years

Intraperitoneal chemotherapy has demonstrated significant pharmacologic and clinical advantage over traditional intravenous administration for cancers that are restricted to the peritoneal cavity. The combination of cytoreductive surgery with hyperthermic intraperitoneal chemotherapy (HIPEC) has become the standard technique used to fight ovarian and gastrointestinal cancers in many centers. However, challenges remain for HIPEC to contact the entire peritoneal surface, penetrate the tumor tissue, and transport to the lymphatics and other metastatic sites. New innovations in delivery technique, such as heated aerosol, and in delivery molecules, such as microparticles, nanoparticles, nanogels, and tumor-penetrating peptides are being tested in animal models and will likely soon be in human trials. Improvements in overall care, such as the recent clinical trial of an oral agent for maintenance therapy in ovarian carcinoma, will continue in this field for the next 20 years.

Time to locoregional recurrence after curative resection of rectal carcinoma is prolonged after neoadjuvant treatment: a systematic review and meta-analysis

AIM

A systematic review of the literature with meta-analysis was performed to evaluate the time to locoregional recurrence after curative resection of rectal carcinoma, assuming that this time is prolonged after neoadjuvant radiochemotherapy and/or present day surgery.

METHOD

English and German language peer-reviewed articles published between 1980 and 2007 were selected. Twenty-five of 118 studies fulfilled the defined inclusion and exclusion criteria. For some special questions, data of the Erlangen Registry of Colorectal Carcinoma (ERCRC) from 1985 to 1997 are reported.

RESULTS

After conventional surgery of rectal carcinoma, 75% (range 66-84%) of locoregional recurrence presented during the first 2 years after resection. Following the introduction of total mesorectal excision surgery and the use of neoadjuvant treatment, a general reduction of the frequency of local recurrence combined with a prolongation of the time to local recurrence was observed. In the practice of today, in particular after neoadjuvant long-course radiochemo-or radiotherapy, 24% (range 8-40%) of all local recurrences present later than 5 years after primary therapy. In contrast, such late local recurrences are observed in only 8% (range 5-9%) following primary surgery alone.

CONCLUSION

For a definite assessment of the therapeutic results regarding local control, a minimal follow up of 7-8 years either after neoadjuvant long-course radiochemo- or radiotherapy and a minimum of 5 years after surgery alone is necessary. For patients with primary surgery followed by adjuvant therapy, it is not possible to make a clear statement.

Radiotherapy in the treatment of resectable rectal adenocarcinoma

The goal of treatment is to cure whereas maintaining sphincter function and minimizing toxicity. Although the mainstay of the treatment is surgery, radiotherapy (RT) is used in a substantial proportion of patients depending on the location and extent of the tumor. The aim of this article is to discuss the role of RT in patients with resectable rectal adenocarcinoma. This article is a review of the pertinent literature. Results show that patients with T1N0 exophytic, well to moderately differentiated, mobile tumors < or = 3 cm in diameter may be treated with either transanal excision or endocavitary RT. The probability of cure with either approach is approximately 80% to 90% and depends on selection criteria. The advantages of endocavitary RT are that it is an outpatient procedure requiring, at most, local anesthesia and is suitable for elderly, infirm patients. The disadvantage is that few of these treatment units are available. Patients who experience a local-regional recurrence may be surgically salvaged. Patients who undergo transanal excision and have unfavorable pathologic findings including equivocal or close margins, poor differentiation, invasion of the muscularis propria, and/or endothelial-lined space invasion have a high risk of local-regional recurrence after surgery alone. The addition of postoperative RT improves the likelihood of cure from 85% to 90%. Patients presenting with unfavorable tumors that are borderline resectable with a transanal excision may be downstaged with preoperative RT and rendered suitable for a wide local excision. The addition of concomitant chemotherapy probably enhances downstaging and may improve the likelihood of sphincter preservation. Patients with T3 and/or N1 rectal cancers have a relatively high probability of local-regional recurrence after surgery alone. Preoperative RT and postoperative RT combined with adjuvant chemotherapy have been shown to significantly reduce the risk of local-regional recurrence and improve survival. Whether preoperative RT alone or combined with chemotherapy is more efficacious than postoperative chemoradiation remains unclear. Endocavitary RT or transanal excision is suitable for patients with T1N0 cancers. Depending on tumor location and extent, adjuvant RT may improve the probability of local-regional control and survival for patients with locally advanced rectal adenocarcinomas.

Local recurrence in rectal cancer: anatomic localization and effect on radiation target

PURPOSE

To determine the sites of local recurrence after total mesorectal excision for rectal cancer in an effort to optimize the radiation target.

METHODS AND MATERIALS

A total of 155 patients with recurrence after abdominal resection for rectal cancer were identified from a population-based consecutive cohort of 2,315 patients who had undergone surgery by surgeons trained in the total mesorectal excision procedure. A total of 99 cross-sectional imaging studies were retrieved and re-examined by one radiologist. The clinical records were examined for the remaining patients.

RESULTS

Evidence of residual mesorectal fat was identified in 50 of the 99 patients. In 83 patients, local recurrence was identified on the imaging studies. All recurrences were within the irradiated volume if the patients had undergone preoperative radiotherapy or within the same volume if they had not. The site of recurrence was in the lower 75% of the pelvis, anatomically below the S1-S2 interspace for all patients. Only 5 of the 44 recurrences in patients with primary tumors >5 cm from the anal verge were in the lowest 20% of the pelvis. Six recurrences involved the lateral lymph nodes.

CONCLUSION

These data suggest that a lowering of the upper limit of the clinical target volume could be introduced. The anal sphincter complex with surrounding tissue could also be excluded in patients with primary tumors >5 cm from the anal verge.

Rectal cancer radiotherapy

Adjuvant therapy for rectal cancer has undergone significant modifications over the past 30 years, including the addition of radiation therapy, significant improvements in surgical technique, and the administration of systemic therapy. Historically, curative resection commonly required an abdominoperineal resection and permanent colostomy. Adjuvant radiation therapy not only improved local control and overall survival, but allowed the opportunity for sphincter-preserving resections in patients with adequate sphincter function and tumors located approximately 1-2 cm from the dentate line. Local recurrence, a primary mode of failure in rectal cancer, has been improved by the development of the total mesorectal excision, with en-bloc resection of the rectum and its lymphovascular mesentery, the mesorectum. Removing micrometastatic disease within the mesorectum has also enhanced sphincter preservation without compromising local control or survival. Locoregional recurrence has remained a significant issue for patients with locally advanced disease (node positive or high T stage). Multiple studies have shown that the addition of chemotherapy further improves outcomes versus surgery alone or combined surgery and radiation, due both to the radiosensitizing properties of certain systemic agents as well as to the direct cytotoxic effect of the chemotherapy on micrometastatic disease. Adjuvant concurrent chemoirradiation in locally advanced rectal cancer confers a significant improvement in local control and overall survival compared with either modality alone. The future direction of treatment for rectal cancer will certainly consist of improved imaging and other diagnostic techniques to determine more accurately the need for adjuvant therapy. Multimodality therapy with radiotherapy administered in combination with systemic and biologic agents as radiation sensitizers is currently under investigation and may allow for improved local control and perhaps allow for minimizing the extent of surgery in selected situations.

Preoperative Chemoradiotherapy for Rectal Cancer: Randomized Trial Comparing Oral Uracil and Tegafur and Oral Leucovorin Vs. Intravenous 5-Fluorouracil and Leucovorin

PURPOSE

To compare, in a randomized trial, 5-fluorouracil (FU) plus leucovorin (LV) (FU+LV) vs. oral uracil and tegafur (UFT) plus LV (UFT+LV) given concomitantly with preoperative irradiation in patients with cT3-4 or N+ rectal cancer.

METHODS AND MATERIALS

A total of 155 patients were entered onto the trial. Patients received pelvic radiotherapy (4500-5,040 cGy in 5 to 6 weeks) and chemotherapy consisting of two 5-day courses of 20 mg/m(2)/d LV and 350 mg/m(2)/d FU in the first and fifth weeks of radiotherapy (77 patients) or one course of 25 mg/d oral LV and 300 mg/m(2)/d UFT for 4 weeks beginning in the second week of radiotherapy (78 patients). The primary endpoints were pathologic complete response (pCR) and resectability rate. Secondary endpoints included downstaging rate, toxicity, and survival.

RESULTS

Grade 3-5 acute hematologic toxicity occurred only with FU+LV (leukopenia 9%; p = 0.02). There were no differences in resectability rates (92.1% vs. 93.4%; p = 0.82). The pCR rate was 13.2% in both arms. Tumor downstaging was more frequent with UFT+LV (59.2% vs. 43.3%; p = 0.04). Three-year overall survival was 87% with FU+LV and 74% with UFT+LV (p = 0.37). The 3-year cumulative incidences of local recurrence were 7.5% and 8.9%, respectively (p = 0.619; relative risk, 1.46; 95% confidence interval 0.32-6.55).

CONCLUSION

Although this study lacked statistical power to exclude clinically significant differences between both groups, the outcome of patients treated with UFT+LV did not differ significantly from that of patients treated with FU+LV, and hematologic toxicity was significantly lower in the experimental arm.

Optimal time interval between capecitabine intake and radiotherapy in preoperative chemoradiation for locally advanced rectal cancer

PURPOSE

Capecitabine and its metabolites reach peak plasma concentrations 1 to 2 hours after a single oral administration, and concentrations rapidly decrease thereafter. We performed a retrospective analysis to find the optimal time interval between capecitabine administration and radiotherapy for rectal cancer.

METHODS AND MATERIALS

The time interval between capecitabine intake and radiotherapy was measured in patients who were treated with preoperative radiotherapy and concurrent capecitabine for rectal cancer. Patients were classified into the following groups. Group A1 included patients who took capecitabine 1 hour before radiotherapy, and Group B1 included all other patients. Group B1 was then subdivided into Group A2 (patients who took capecitabine 2 hours before radiotherapy) and Group B2. Group B2 was further divided into Group A3 and Group B3 with the same method. Total mesorectal excision was performed 6 weeks after completion of chemoradiation and the pathologic response was evaluated.

RESULTS

A total of 200 patients were enrolled in this study. Pathologic examination showed that Group A1 had higher rates of complete regression of primary tumors in the rectum (23.5% vs. 9.6%, p = 0.01), good response (44.7% vs. 25.2%, p = 0.006), and lower T stages (p = 0.021) compared with Group B1; however, Groups A2 and A3 did not show any improvement compared with Groups B2 and B3. Multivariate analysis showed that increases in primary tumors in the rectum and good response were only significant when capecitabine was administered 1 hour before radiotherapy.

CONCLUSION

In preoperative chemoradiotherapy for rectal cancer, the pathologic response could be improved by administering capecitabine 1 hour before radiotherapy.

Radiation therapy for gastrointestinal cancer

This article has reviewed the current role of radiation in the treatment of gastrointestinal malignancies and discussed the data supporting its use. Radiation treatment in this setting continues to evolve with the increasing implementation of more conformal delivery techniques. Further scientific investigation is needed to establish the optimal role of radiation and to better define its integration with novel systemic and biologic modalities.

Definition and delineation of the clinical target volume for rectal cancer

PURPOSE

Optimization of radiation techniques to maximize local tumor control and to minimize small bowel toxicity in locally advanced rectal cancer requires proper definition and delineation guidelines for the clinical target volume (CTV). The purpose of this investigation was to analyze reported data on the predominant locations and frequency of local recurrences and lymph node involvement in rectal cancer, to propose a definition of the CTV for rectal cancer and guidelines for its delineation.

METHODS AND MATERIALS

Seven reports were analyzed to assess the incidence and predominant location of local recurrences in rectal cancer. The distribution of lymphatic spread was analyzed in another 10 reports to record the relative frequency and location of metastatic lymph nodes in rectal cancer, according to the stage and level of the primary tumor.

RESULTS

The mesorectal, posterior, and inferior pelvic subsites are most at risk for local recurrences, whereas lymphatic tumor spread occurs mainly in three directions: upward into the inferior mesenteric nodes; lateral into the internal iliac lymph nodes; and, in a few cases, downward into the external iliac and inguinal lymph nodes. The risk for recurrence or lymph node involvement is related to the stage and the level of the primary lesion.

CONCLUSION

Based on a review of articles reporting on the incidence and predominant location of local recurrences and the distribution of lymphatic spread in rectal cancer, we defined guidelines for CTV delineation including the pelvic subsites and lymph node groups at risk for microscopic involvement. We propose to include the primary tumor, the mesorectal subsite, and the posterior pelvic subsite in the CTV in all patients. Moreover, the lateral lymph nodes are at high risk for microscopic involvement and should also be added in the CTV.

Peritoneal carcinomatosis of colorectal origin: incidence and current treatment strategies

OBJECTIVE

To review the literature with regard to the incidence and prognostic significance of peritoneal seeding during surgery for primary colorectal cancer (CRC), the incidence of intraperitoneal recurrence of CRC, and the current treatment strategies of established PC of colorectal origin, with special focus on cytoreductive surgery and intraperitoneal chemotherapy (IPEC).

SUMMARY BACKGROUND DATA

Although hematogenous dissemination forms the greatest threat to patients with CRC, peritoneal carcinomatosis (PC), presumably arising from intraperitoneal seeding of cancer cells, is a relatively frequent event in patients with recurrent CRC.

METHODS

The PubMed and Medline literature databases were searched for pertinent publications regarding the incidence and prognostic significance of exfoliated tumor cells in the peritoneal cavity during curative surgery for primary CRC, the incidence of intraperitoneal recurrence of CRC, and the therapeutic results of systemic chemotherapy or cytoreductive surgery followed by IPEC.

RESULTS

The incidence of peritoneal seeding during potentially curative surgery for primary CRC, as reported in 12 patient series, varied widely, from 3% to 28%, which may be explained by differences in methods to detect tumor cells. PC is encountered in approximately 7% of patients at primary surgery, in approximately 4% to 19% of patients during follow-up after curative surgery, in up to 44% of patients with recurrent CRC who require relaparotomy, and in 40% to 80% of patients who succumb to CRC. The reported median survival after systemic 5-fluorouracil-based chemotherapy for PC varies from 5.2 to 12.6 months. Median survival after aggressive cytoreductive surgery followed by (hyperthermic) IPEC in selected patients, as reported in 16 patient series, tends to be better and varies from 12 to 32 months at the cost of morbidity and mortality rates of 14% to 55% and 0% to 19%, respectively. One randomized controlled trial has been published confirming the superiority of aggressive surgical cytoreduction and intraperitoneal chemotherapy over strictly palliative treatment.

CONCLUSIONS

Peritoneal seeding of cancer cells possibly leading to PC is a rather common phenomenon in patients with CRC. Cytoreductive surgery and adjuvant (hyperthermic) IPEC have been shown to be efficacious in selected patients and should therefore be considered in patients with resectable PC of colorectal origin.

Optimal timing for the administration of capecitabine with preoperative chemoradiation for locally advanced rectal cancer

PURPOSE

Capecitabine is an oral fluoropyrimidine carbamate and it is known as an effective radiosensitizer. Capecitabine and its metabolite reach their peak concentration in the plasma at 1 approximately 2 hours after a single oral administration of capecitabine and the levels fall rapidly thereafter. To verify the radiosensitizing effect of capecitabine that is based on such pharmacokinetic characteristics, we performed a retrospective analysis on the optimal timing of capecitabine administration with performing preoperative chemoradiation for locally advanced rectal cancer.

MATERIALS AND METHODS

Among 171 patients who were treated with preoperative radiotherapy and concurrent capecitabine administration for rectal cancer, 56 patients were administered capecitabine at 1~2 hours before radiotherapy (group A), and at other time in the other 115 patients (group B). Total mesorectal excision was done at 4 to 6 weeks after the completion of chemoradiation. The radiosensitizing effect of capecitabine was evaluated on the basis of the pathological response.

RESULTS

Complete pathological regression of the primary tumor was observed in 12 patients (21.4%) for group A and in 11 patients (9.6%) for group B (p=0.031). Residual disease less than 0.5 cm (a good response) was observed in 19 patients (33.9%) for group A and in 23 patients (20.0%) for group B (p=0.038). On multivariate analysis, the capecitabine ingestion time showed marginal significance.

CONCLUSION

When performing preoperative chemoradiation for locally advanced rectal cancer, the radiosensitizing effect of capecitabine was enhanced when it was administered 1 hour before radiotherapy.

Radiological findings do not support lateral residual tumour as a major cause of local recurrence of rectal cancer

BACKGROUND

The aim of this study was to determine the sites of local recurrence following radical (R0) total mesorectal excision (TME) for rectal cancer in an effort to elucidate the reasons for recurrence.

METHODS

Thirty-seven patients with recurrence following curative resection for rectal cancer were identified from a population of 880 patients operated on by surgeons trained in the TME procedure. Two radiologists independently examined 33 available computed tomograms and magnetic resonance images taken when the recurrence was detected.

RESULTS

Twenty-nine of the 33 recurrences were found in the lower two-thirds of the pelvis. Two recurrent tumours appeared to originate from lateral pelvic lymph nodes. Evidence of residual mesorectal fat was identified in 15 patients. Fourteen of the recurrent tumours originated from primary tumours in the upper rectum; all of these tumours recurred at the anastomosis and 12 of the 14 patients had evidence of residual mesorectal fat.

CONCLUSION

Lateral pelvic lymph node metastases are not a major cause of local recurrence after TME. Partial mesorectal excision may be associated with an increased risk of local recurrence from tumours in the upper rectum.

Prevention and therapy of colorectal cancer

Colorectal cancer is expected to affect more than 146,000 and kill more than 57,000 Americans in 2004. Increased understanding of carcinogenesis is transforming clinical approaches to all stages of this disease. During the last 5 years, four new drugs have been approved for colorectal cancer treatment, and substantial progress has been made in identifying and developing agents that prevent or delay carcinogenesis. These advances substantiate target-driven approaches to cancer prevention and treatment, and provide fruitful opportunities for future investigations.

Adjuvant postoperative radiotherapy for colon carcinoma

BACKGROUND

The objective of this report was to review the role of adjuvant postoperative radiotherapy (RT) for patients with adenocarcinoma of the colon.

METHODS

The authors reviewed the pertinent literature.

RESULTS

Data suggested that locoregional postoperative RT improves both local control and survival for patients with T4N0-N1 tumors. There also may be a benefit for patients with T3N1-N2 tumors, but the data were equivocal. Whole abdominal RT may result in a similar benefit but is associated with increased toxicity.

CONCLUSIONS

Postoperative RT should be considered for patients with T4N0-N1 colon carcinoma. Locoregional fields should be used.

Efficacy of postoperative concurrent chemoradiation for resectable rectal cancer: a single institute experience

PURPOSE

For patients with Dukes' stage B and C rectal cancer, surgery followed by adjuvant chemoradiotherapy is considered to be the standard treatment. However, the drugs used in combination with 5-fluorouracil (5-FU), the method of administration, duration of adjuvant therapy and the frequencies of administration presently remain controversial topics. We investigated (1) the efficacy and safety of adjuvant radiotherapy and 5-FU/leucovorin (LV) chemotherapy for patients who had undergone curative resection and (2) the effect of dose related factors of 5-FU on survival.

MATERIALS AND METHODS

130 rectal cancer patients with Dukes' B or C stage disease who were treated with curative resection were evaluated. The adjuvant therapy consisted of two cycles of 5-FU/LV chemotherapy followed by pelvic radiotherapy with chemotherapy, and then 4 approximately 10 more cycles of the same chemotherapy regimen were delivered based on the disease stage. The cumulative dose of 5-FU per body square meter (BSA), actual dose intensity and relative dose intensity were obtained. The patients were divided into two groups according to the median value of each factor, and the patients' survival rates were compared.

RESULTS

With a median follow-up duration of 52 months, the 5-year disease-free survival and overall survival rates of 130 patients were 57% and 73%, respectively. Locoregional failure occurred in 17 (13%) of the 130 patients, and the distant failure rate was 27% (35/130). The chemotherapy related morbidity was minimal, and there was no mortality for these patients. The cumulative dose of 5-FU/BSA had a significant effect on the 5-year overall survival for Dukes' C rectal cancer patients (p=0.03). Multivariate analysis demonstrated that only the performance status affected the 5-year overall survival (p=0.003).

CONCLUSION

An adjuvant therapy of radiotherapy and 5-FU/LV chemotherapy is effective and tolerable for Dukes' B and C rectal cancer patients. A prospective, multicenter, randomized study to evaluate the effects of the cumulative dose of 5-FU/BSA on survival is required.

CT-fluoroscopy guided interstitial brachytherapy with image-based treatment planning for unresectable locally recurrent rectal carcinoma

PURPOSE

The aim of the study is to develop high-dose-rate (HDR) conformal interstitial brachytherapy by means of combined CT-fluoroscopy guidance with CT-based treatment planning for locally recurrent rectal carcinoma.

METHODS AND MATERIALS

Brachytherapy needle insertion was guided with a helical CT scanner providing continuous fluoroscopy reconstruction. A video monitor placed adjacent to the CT gantry simultaneously allowed the operator to see the process of needle insertion. Final CT images were transferred by an online system to the treatment-planning computer, which reconstructed the implant needles and organ contours. The doses in planning target volume were normalized and geometrically optimized. The patients received a brachytherapy dose at 5 Gy twice daily with a hypofractionated accelerated schedule at a total dose of 30-50 Gy with or without external radiation therapy. Eighteen patients were treated with this procedure.

RESULTS

Ten to thirty-six needles (average, 17.3) were successfully placed to the planning target volume in each patient. The average time for CT fluoroscopy was 357 seconds for each procedure. No accident was seen at needle insertion, but 2 patients developed incomplete peroneal nerve palsy after needle removal, but gradually recovered. CT-based treatment planning was faster and more accurate than projection reconstruction with conventional radiograms. Analysis of the dose volume histogram showed conformal dose distribution to the target, while avoiding normal structures.

CONCLUSION

CT fluoroscopy guidance ensures safety and increases the accuracy of needle placement in brachytherapy. Conformal high-dose-rate (HDR) interstitial brachytherapy with CT-based treatment planning is a method worth considering for locally recurrent rectal cancer.

Preoperative chemoradiation for locally advanced rectal adenocarcinoma-the University of Florida experience

To evaluate the efficacy of preoperative radiotherapy alone or combine with chemotherapy. Between 1975 to 1997, 318 patients with locally advanced rectal adenocarcinomas were treated with preoperative radiation therapy. Between 1991 and 1997, approximately 60% of patients received fluorouracil (5-FU)-based adjuvant chemotherapy. Patients treated since 1991 had improved downstaging compared with those treated prior to 1991. Patients treated between 1991 and 1997 were also more likely to undergo a sphincter preserving surgical procedure. Preoperative chemoradiation probably results in improved downstaging and survival compared with preoperative irradiation alone.

Advances in combined radiation therapy for the management of rectal cancer

Significant advances have been made in the use of adjuvant radiation for patients with localized rectal cancer. Recent progress in adjuvant postoperative radiation regimens relates to the integration of systemic therapy into radiation, as well as redefining the techniques and sequences for both modalities. The adjuvant radiation management approach in both North America and Europe has been shifting towards preoperative adjuvant therapy to promote sphincter-preserving surgery and to decrease acute and late toxicity. Although 5-fluorouracil-based chemotherapy in combination with radiation remains the standard adjuvant therapy for rectal cancer, the integration of novel chemotherapeutic agents and biologic modulators remains an active area of investigation.

Sites of local recurrence after surgery, with or without chemotherapy, for rectal cancer: implications for radiotherapy field design

PURPOSE

To examine the sites of pelvic recurrence in patients with rectal cancer previously untreated with radiotherapy to determine the relative frequency and location of recurrence within the pelvis.

METHODS AND MATERIALS

The records of patients with locally recurrent rectal cancer referred to three radiation oncology departments between 1984 and 1997 were reviewed. The data collected included the date and type of the initial resection and the pathologic findings. The site of recurrence within the pelvis, presence of metastasis, and date of recurrence were documented.

RESULTS

A total of 269 patients were included. Tumor had invaded through the muscularis in 74% and involved other organs in 9%. Fifty-two percent of patients were node positive at initial surgery. The median time to local recurrence from surgery was 18 months (range 15-20) and from local recurrence to death was 14 months (range 12-17). Both the initial tumor stage and the resection type influenced the recurrence location within the pelvis (p <0.01). T4 tumors comprised only 9% of initial T stage tumors but accounted for 38% of anterior central pelvic recurrences (p <0.01). All perineal recurrences occurred after abdominoperineal resection. The sites of recurrence within the pelvis were the posterior central pelvis (47%) and anastomotic (21%).

CONCLUSION

If those patients with T4 tumors at presentation were excluded, 89% had local recurrence at, or posterior to, the anastomosis. Furthermore, if we exclude both patients who underwent abdominoperineal resection and those with T4 tumors at presentation, the rate increases to 93%. The rate of recurrence anteriorly (7%) does not justify routine radiation of the anterior pelvis beyond that required to adequately cover the anastomotic site.

Chemotherapy for colorectal cancer

With effective chemotherapy as adjuvant treatment, the survival benefit is clearly achieved for certain (stage III) colorectal cancer patients, though there still exist many unsettled issues including the controversies in the treatment of stage II disease. Advances in the development of a new generation of cytotoxic agents in the past several years have allowed us to move forward from the "fluorouracil-only era" in the treatment of advanced/metastatic colorectal cancer. It is still not very clear how best to minimize toxicity without compromising efficacy of the combination therapy with newer agents, or how to maximize the benefit of chemotherapy (concurrent versus sequential). There are many current ongoing clinical trials designed to address these issues. With better understanding of the signal transduction and molecular biology characteristics of colorectal cancer, and the development of biologic and molecular target agents, the outcomes of patients with colorectal cancer will be improved further. Future clinical trials should be focused on optimizing and individualizing therapy for patients based on their molecular profiles to achieve maximal clinical benefit.

Chemoradiotherapy in the treatment of rectal cancer

The integration of radiotherapy to the adjuvant treatment of rectal cancer was prompted by the predominance of locoregional failures after curative surgery. This characteristic in the pattern of failure is one of the main reasons adjuvant radiotherapy plays a greater role in rectal cancer than in colon cancer. It has been demonstrated that local failure rates after surgery alone for rectal cancer are strongly dependent on the degree of bowel wall invasion, lymph node involvement, and margins of resection. These same locoregional factors are also predictive of distant metastasis and survival. In addition, local failure is associated with devastating symptoms that severely affect the quality of life of patients. For these reasons, locoregional control remains a major issue in the treatment of rectal cancer. This article summarizes the evidence that has established chemoradiotherapy as part of the standard of care for rectal cancer and the techniques used for its delivery.

The variability of the clinical target volume for rectal cancer due to internal organ motion during adjuvant treatment

PURPOSE

This study defined the clinical target volume (CTV) for the adjuvant treatment of rectal cancer and applied this definition to multiple CT scans obtained during the typical 5-week course of treatment to measure the modification to the CTV due to internal organ motion that would be needed to define the planning target volume (PTV).

METHODS AND MATERIALS

Ten patients with rectal cancer had weekly treatment planning CT scans during adjuvant radiation therapy. All patients were given oral contrast, placed prone on a rigid foam cradle with a depressed area for small bowel exclusion, and instructed to have a full bladder. The CT scans were registered according to the bones of the pelvis, and the CTV was outlined on each CT slice. Movement of the CTV in all dimensions was measured. The CT scan with the lowest and highest bladder volume for each patient was used to calculate the CTV movement due to bladder filling.

RESULTS

The largest difference in the CTV occurred 10 cm caudal to the anus, with a standard deviation of 1 cm. Bladder filling displaced the anterior border of the CTV an average of 7 mm over a cranial to caudal length of 2.5 cm. Other borders of the CTV were based on muscle, bone, or major blood vessels and were stable.

CONCLUSION

Modification of the CTV to design a PTV can be unequal, with the largest change at the anterior border of the inferior pelvis.

Adjuvant therapy in rectal cancer: analysis of stage, sex, and local control--final report of intergroup 0114

PURPOSE

The gastrointestinal Intergroup studied postoperative adjuvant chemotherapy and radiation therapy in patients with T3/4 and N+ rectal cancer after potentially curative surgery to try to improve chemotherapy and to determine the risk of systemic and local failure.

PATIENTS AND METHODS

All patients had a potentially curative surgical resection and were treated with two cycles of chemotherapy followed by chemoradiation therapy and two additional cycles of chemotherapy. Chemotherapy regimens were bolus fluorouracil (5-FU), 5-FU and leucovorin, 5-FU and levamisole, and 5-FU, leucovorin, and levamisole. Pelvic irradiation was given to a dose of 45 Gy to the whole pelvis and a boost to 50.4 to 54 Gy.

RESULTS

One thousand six hundred ninety-five patients were entered and fully assessable, with a median follow-up of 7.4 years. There was no difference in overall survival (OS) or disease-free survival (DFS) by drug regimen. DFS and OS decreased between years 5 and 7 (from 54% to 50% and 64% to 56%, respectively), although recurrence-free rates had only a small decrease. The local recurrence rate was 14% (9% in low-risk [T1 to N2+] and 18% in high-risk patients [T3N+, T4N]). Overall, 7-year survival rates were 70% and 45% for the low-risk and high-risk groups, respectively. Males had a poorer overall survival rate than females.

CONCLUSION

There is no advantage to leucovorin- or levamisole-containing regimens over bolus 5-FU alone in the adjuvant treatment of rectal cancer when combined with irradiation. Local and distant recurrence rates are still high, especially in T3N+ and T4 patients, even with full adjuvant chemoradiation therapy.

Role of radiation therapy in the treatment of resectable rectal adenocarcinoma

The purpose of this study is to review the role of radiation therapy in the treatment of resectable rectal adenocarcinoma. Selection criteria, treatment techniques, and results are discussed.

Intraoperative radiation therapy for curatively resected rectal cancer

PURPOSE

Intraoperative radiotherapy has been used for local control of locally advanced rectal cancer. The aim of this study was to investigate the efficacy of intraoperative radiotherapy for curatively resected rectal cancer.

METHODS

Between 1982 and 1998, intraoperative radiotherapy was administered in combination with curative resection in 78 patients with adenocarcinoma of the middle or lower third of the rectum (intraoperative radiotherapy group). Sixty-two of the patients had received preoperative radiotherapy with 20 Gy. Intraoperative radiotherapy was performed by a new strategy in which an electron beam was administered as uniformly as possible to the entire dissected surface of the pelvis. Retrospective comparisons were made with 248 patients treated by surgery alone during the same period (non-intraoperative radiotherapy group).

RESULTS

The differences in tumor stage or surgical procedures between the two groups were not statistically significant. Survival, disease-free survival, and local recurrence-free survival in the intraoperative radiotherapy group were significantly more favorable than in the non-intraoperative radiotherapy group (P = 0.01, P = 0.04, and P = 0.02). Differences in survival were observed in Stage II patients but not in Stage I or Stage III patients. The local failure rate was 2.6 percent in the intraoperative radiotherapy group and 11.3 percent in the non-intraoperative radiotherapy group, and the difference was significant (P = 0.02). The distant metastasis rate was 18.0 percent in the intraoperative radiotherapy group and 19.5 percent in the non-intraoperative radiotherapy group, and the difference was not significant. There was a significantly higher rate of wound infection in the intraoperative radiotherapy group, but no infections were serious.

CONCLUSIONS

In patients with adenocarcinoma of the middle or lower third of the rectum, intraoperative radiotherapy to the entire dissected surface of the pelvis reduced local recurrence in Stage II and Stage III patients and improved survival in Stage II patients.

[Clinical target volume for preoperative radiotherapy of rectal cancers]

The total mesorectal excision allows the marked increase of the local control rate in rectal cancer. Therefore, the mesorectal space is the usual field for the spread of rectal cancer cells. It could therefore be considered as the clinical target volume in the preoperative plan by the radiation oncologist. We propose to identify the mesorectum on anatomical structures of a treatment-position CT scan.

CONSERVATIVE TREATMENT OF RECTAL ADENOCARCINOMA

Endocavitary radiotherapy and transrectal excision are highly effective treatments for properly selected patients with favorable early-stage rectal adenocarcinoma. The likelihood of local control and survival after treatment with either modality is similar, and differences among various series probably reflect selection. The parameter most predictive of local control and survival in the authors' series was tumor configuration. As has been previously observed, "selection is the silent partner of success." Suitable candidates for endocavitary radiotherapy or wide local excision are patients whose tumors are 3 cm or less in diameter, well-to-moderately differentiated, exophytic, mobile, limited to the submucosa on transrectal ultrasound, and within 10 cm of the anal verge. The advantages of endocavitary irradiation are (1) it is an outpatient procedure, (2) it does not require anesthesia, and (3) it is less expensive than transrectal excision. The advantages of transrectal excision are (1) it may be performed during one brief hospitalization (as opposed to four outpatient visits), and (2) a small subset of patients will have pathologic findings predicting an increased risk of regional lymph node involvement, revealing the need to treat the nodes with external-beam radiotherapy. A disadvantage of wide local excision is that some patients who would be suitable for a local procedure alone must be subjected to a course of external-beam radiotherapy when they are found to have equivocal or positive margins. Patients who are treated with transrectal excision and external-beam radiotherapy have less favorable lesions and are not comparable with patients who are treated with endocavitary radiotherapy or wide local excision alone. They are best compared with patients who have undergone major surgery consisting of abdominoperineal resection or low anterior resection. Because the risk of positive nodes is significantly increased with adverse pathologic findings such as poor differentiation, invasion of the muscularis propria, and endothelial-lined space invasion, a subset of these patients treated with wide local excision would have positive nodes. This subset of patients is not comparable with patients with stage pT1N0 and pT2N0 tumors treated with major surgery. The latter group of patients undergo complete surgical staging, whereas the pathologic staging for patients who undergo wide local excision and radiotherapy is limited to the extent of the primary tumor. With this caveat in mind, wide local excision and radiotherapy seem to result in locoregional control and survival rates similar to the rates obtained with major surgery for patients with pT1 and pT2 cancers (Table 5). Patients who should receive postoperative irradiation have tumors that exhibit one or more of the following characteristics: size greater than 3 cm in diameter, poorly differentiated, invasion of the muscularis propria, endothelial-lined space invasion, fragmented resection, equivocal or positive margins, or perineural invasion. Patients with gross residual disease are not suitable candidates for radiotherapy and require further surgery. The authors' policy is to treat these patients with chemoradiation followed by resection. Patients thought to have transmural invasion before treatment are probably best treated with preoperative chemoradiation combined with major surgery, although a subset of patients can be downstaged and rendered suitable for a wide local excision.