Surgical adjuvant therapy for rectal cancer: present options

Localized Rectal Cancer: Indian Consensus and Guidelines

The rising incidence of colorectal cancer (CRC) in India, particularly the prevalence of rectal cancer over colon cancer (0.7:1), has been a growing concern in recent decades; especially notable is the trend of increasing cases among young CRC patients. Given the diverse treatment approaches for rectal cancer globally and the varying economic capacities of patients in low to middle-income countries (LMICs) like India, it is essential to establish consensus guidelines that are specifically tailored to meet the needs of these patients. To achieve this, a panel comprising 30 eminent rectal cancer experts convened to conduct a comprehensive and impartial evaluation of existing practices and recent advancements in the field. Through meticulous scrutiny of published literature and a consensus-building process that involved voting on pertinent questions, the panel formulated management strategies. These recommendations are the result of a rigorous, evidence-based process and encapsulate the collective wisdom and judgment of leading authorities in the field.

The multidisciplinary management of gastrointestinal cancer. Multimodal treatment of rectal cancer

Greater understanding of the natural history of rectal cancer, and the knowledge that a histologically involved circumferential margin due to inadequate lateral dissection confers a high risk of local recurrence have driven technical advances in surgical technique with meticulous surgical dissection along embryological planes. Significant improvements in local control and overall survival have been seen for patients with resectable rectal cancer. However, even high-quality surgery cannot always achieve a curative resection for locally advanced cancers that extend below the levators, having transgressed the mesorectal fascia. Magnetic resonance imaging is now accepted as a practical method of clinical staging, and can accurately predict pre-operatively the likelihood of achieving a clear circumferential margin. Technological advances in radiation planning and new effective cytotoxic drugs also give scope for dealing with unresectable rectal cancer, and the potential for controlling distant micrometastases. Hence, modern multimodal treatment of rectal cancer attempts to integrate surgery, radiotherapy and chemotherapy, and address the two distinct problems of local recurrence and metastatic disease. Multidisciplinary teams achieve the best results. This paper discusses the surgical management of rectal cancer, the pathology, the principles of imaging, and the lessons learnt from randomized trials of radiotherapy and chemoradiation.

Preoperative therapy for lower rectal cancer and modifications in distance from anal sphincter

PURPOSE

To assess the frequency and magnitude of changes in lower rectal cancer resulting from preoperative therapy and its impact on sphincter-saving surgery. Preoperative therapy can increase the rate of preserving surgery by shrinking the tumor and enhancing its distance from the anal sphincter. However, reliable data concerning these modifications are not yet available in published reports.

METHODS AND MATERIALS

A total of 98 cases of locally advanced cancer of the lower rectum (90 Stage uT3-T4N0-N+ and 8 uT2N+M0) that had undergone preoperative therapy were studied by endorectal ultrasonography. The maximal size of the tumor and its distance from the anal sphincter were measured in millimeters before and after preoperative therapy. Surgery was performed 6-8 weeks after therapy, and the histopathologic margins were compared with the endorectal ultrasound data.

RESULTS

Of the 90 cases, 82.5% showed tumor downsizing, varying from one-third to two-thirds or more of the original tumor mass. The distance between the tumor and the anal sphincter increased in 60.2% of cases. The median increase was 0.73 cm (range, 0.2-2.5). Downsizing was not always associated with an increase in distance. Preserving surgery was performed in 60.6% of cases. It was possible in nearly 30% of patients in whom the cancer had reached the anal sphincter before the preoperative therapy. The distal margin was tumor free in these cases.

CONCLUSION

The results of our study have shown that in very low rectal cancer, preoperative therapy causes tumor downsizing in >80% of cases and in more than one-half enhances the distance between the tumor and anal sphincter. These modifications affect the primary surgical options, facilitating or making sphincter-saving surgery possible.

Thymidine phosphorylase and dihydropyrimidine dehydrogenase expression levels in tumor and normal tissue specimens of T3 human colorectal carcinoma

PURPOSE

Thymidine phosphorylase (TP) and dihydropyrimidine dehydrogenase (DPD) are important enzymes related to the metabolism of 5-fluorouracil and its derivatives. We evaluated the association between the clinicopathological factors and these enzymes in patients with T3 colorectal carcinoma.

METHODS

The TP and DPD expression levels in 15 patients with T3 colorectal carcinomas were measured in tumor and adjacent normal tissue specimens by enzyme-linked immunosorbent assay. Correlations between each enzyme and clinicopathological factors were also statistically evaluated.

RESULTS

The TP levels in tumor and normal tissue specimens were 77.9 +/- 33.6 and 24.7 +/- 10.3, respectively (P < 0.001). The DPD levels in tumor and normal tissue specimens were 44.1 +/- 18.2 and 53.1 +/- 24.1, respectively (P = 0.46). The TP/DPD ratios in tumor and normal tissue specimens were 1.84 +/- 0.52 and 0.53 +/- 0.26, respectively (P < 0.001). The tumor/normal ratios of TP level in patients with and without liver metastasis were 1.79 +/- 0.91 and 4.67 +/- 2.51, respectively (P = 0.024).

CONCLUSION

The measurement of the enzyme expression levels of TP and DPD is considered to be useful for better understanding the conditions of tumor progression. The mechanisms of regulation of these enzymes thus require further evaluation.

Preoperative UFT administration for patients with advanced colorectal cancer--increased uptake of 5-fluorouracil by tumor tissue is a prognostic factor

The aim of this study was to clarify whether increased 5-fluorouracil (5-FU) uptake by tumor tissue following preoperative UFT administration is a prognostic factor after surgery in colorectal cancer patients. We examined the concentrations of 5-FU in tumor or normal tissue of 96 colorectal cancer patients who received UFT (400 mg/day) orally for 7 days prior to surgery. Patients were divided into two groups with high or low 5-FU concentrations in tumor tissue (defined as higher or lower than the cut-off value, respectively). The cut-off value of 5-FU was established based on the upper limit of the 95% confidence interval of the median of the concentration found in normal tissue (0.106 microg/g). Of the 96 patients, 62 (64.6%) were in the low-5-FU group and 34 (35.4%) in the high-5-FU group. The latter had a more favorable clinical outcome (p=0.0465). Cox regression analysis revealed that two independent variables, stage and 5-FU status in tumor tissue, were significant for prediction of survival. These findings suggest that increased uptake of 5-FU by tumor tissue following preoperative oral administration of UFT is an independent prognostic factor in colorectal cancer patients. This variable needs to be considered in the design of future therapeutic trials.

Suppository administration of chemotherapeutic drugs with concomitant radiation for rectal cancer

PURPOSE

Preoperative radiation with combined chemotherapy is effective in shrinking advanced rectal cancer locally and facilitating subsequent surgery. Suppository delivery of 5-fluorouracil is associated with less toxicity and higher rectal tissue concentrations than intravenous administration. This prompted us to evaluate suppository and intravenous administration of 5-fluorouracil and mitomycin C with concomitant radiation to determine associated toxicity.

METHODS

Rectal, liver, lymph node, and lung tissue and systemic and portal blood were collected serially from male Sprague Dawley rats to determine drug concentrations following suppository or intravenous delivery of 5-fluorouracil or mitomycin C. Thirty-six animals were randomly assigned to treatment groups and received 5-fluorouracil suppositories, mitomycin C suppositories, or an equivalent intravenous dose of 5-fluorouracil or mitomycin C 30 minutes before radiation therapy. Before and 3, 6, 10, and 15 days following this treatment, blood was collected, colonoscopy was performed, and rectal tissue was harvested for histologic examination.

RESULTS

Mitomycin C suppository was significantly less toxic compared with intravenous delivery, and higher rectal tissue concentrations were observed from 10 to 30 minutes (P < 0.05). Compared with intravenous 5-fluorouracil administration and radiation, 5-fluorouracil suppository and radiation resulted in additive myelosuppression at day 6 (P < 0.05) with rapid recovery.

CONCLUSIONS

5-Fluorouracil and mitomycin C suppository delivery combined with radiation causes less systemic toxicity and is more effective than intravenous administration.

Suppository delivery of 5-fluorouracil in rectal cancer

BACKGROUND

Preoperative radiotherapy with concomitant intravenous 5-fluorouracil (5-FU-i.v.) is effective in shrinking locally advanced rectal cancers and facilitating subsequent surgery. Topical 5-FU application may enhance its radiosensitizing and cytotoxic effects. Suppository and intravenous 5-FU administration were compared with respect to myelo-suppression and tissue concentrations.

METHODS

Rats received 120 mg/kg 5-FU-i.v. or via suppository (5-FU-S). White blood cell count, serum albumin, alkaline phosphatase, creatinine, and aspartate aminotransferase (AST) were determined before and serially after 5-FU administration. In a separate experiment, rats received 5-FU-S or 5-FU-i.v. as already described. Portal and systemic blood, rectal, iliac lymph node, liver, and lung tissue were harvested for high-performance liquid chromatography determination of 5-FU concentrations 30 min, 1, 3, 6, and 12 h after drug administration.

RESULTS

No toxicity was observed in 5-FU-S animals, whereas 63% of 5-FU-IV animals had diarrhea. Weight loss and myelosuppression occurred only in 5-FU-i.v. animals. Rectal drug concentrations were significantly higher in the 5-FU-S animals compared with 5-FU-i.v. animals, 0.5-6 h after drug administration. Blood, liver, and lung 5-FU concentrations with 5-FU-S were comparable to those with 5-FU-i.v.

CONCLUSIONS

5-FU suppositories are associated with fewer systemic side effects and higher rectal 5-FU concentrations than with 5-FU-i.v. administration.

Adjuvant treatment of colon and rectal cancer: impact of chemotherapy, radiotherapy, and immunotherapy on routine postsurgical patient management. Forschungsgruppe Onkologie Gastrointestinaler Tumoren (FOGT)

Colon cancer patients with UICC stage III or T4 N0 M0 stage II should receive postoperative adjuvant therapy, since relapse rates are high and surgical outcome has been improved by adjuvant treatment. The standard treatment is 5-fluourouracil plus levamisole; an alternative option is the combination of 5-fluourouracil and folinic acid. Stage II (T3 N0 M0) colon cancer patients should not receive adjuvant treatment outside of studies. Rectal cancer patients of stage II or III should receive postoperative radiochemotherapy with 45-54.4 Gy and 5-fluourouracil as standard treatment. Patients not eligible for radiotherapy may receive adjuvant chemotherapy only. Studies need to be conducted to improve adjuvant therapy in colorectal cancer. All qualified patients should be treated within these studies requiring sufficient patient numbers, as well as comparable surgical procedures, proper patient selection and stratification criteria, drug and dose intensities. Intraportal infusion may be as effective as systemic adjuvant treatment; the tumor type and stage for which benefit from this kind of treatment is consistently significant needs to be defined, since intraportal infusion of all resectable colorectal cancers is overtreatment. Both surgery and histopathological staging may be improved in some centers, and these require standardization and quality control.