Adjuvant therapy for colorectal cancer: past accomplishments, future directions

Hypoxia, angiogenesis and apoptosis markers in locally advanced rectal cancer

BACKGROUND AND AIMS

Hypoxia-inducible factor 1alpha (HIF-1alpha) is a critical regulatory protein of cellular response to hypoxia. HIF-1alpha triggers the angiogenic process through activation of the vascular endothelial factor (VEGF) gene. The bcl-2 anti-apoptotic and the death promoting p53 genes, regulate the apoptotic cell death. We investigated the relationship between hypoxia, angiogenesis and apoptosis and their prognostic impact in patients with advanced rectal cancer.

PATIENTS AND METHODS

The immunohistochemical expression of HIF-1alpha, VEGF, p53 and bcl-2 and the determination of microvessel density (MVD), apoptotic index (AI) were carried out in tumour tissue samples obtained from 92 patients with locally advanced rectal cancer (LARC) (T3,4/N+/-).

RESULTS

HIF-1alpha high reactivity and VEGF overexpression were noted in 47.8 and 44.6% of the examined cases, respectively. They significantly correlated with lymph node metastasis (P<0.001) and low rectal location (P=0.016). HIF-1alpha expression was directly correlated with VEGF up-regulation (P<0.001) and MVD (P<0.001). VEGF expression was closely interrelated with MVD (P<0.001). In univariate analysis advanced grade, infiltrative pattern of tumour growth, vascular invasion, positive lymph node status, HIF-1alpha expression and VEGF upregulation were related to decreased disease-free and overall survival. In multivariate analysis, only high HIF-1alpha reactivity and positive lymph node status emerged as independent variables of adverse prognostic significance.

CONCLUSION

HIF-1alpha and VEGF may play an important predictive and prognostic role in patients with LARC.

Prognostic value of p27, p53, and vascular endothelial growth factor in Dukes A and B colon cancer patients undergoing potentially curative surgery

PURPOSE

Early-stage colon cancer patients (Dukes A or B; pT1-T3 pNO pMO) are excluded from adjuvant chemotherapy following potentially curative surgery because they are expected to have good long-term survival. However, 20 percent to 30 percent of these patients ultimately succumb from recurrent disease. This indicates that the conventional staging procedures may be unable to precisely predict cancer prognosis.

METHODS

In 65 early-stage colon cancers, we investigated by immunohistochemistry the role of molecular markers such as p27, p53, and vascular endothelial growth factor in identifying high-risk patients who may benefit from adjuvant treatments.

RESULTS

No clinicopathologic factor, namely Dukes stage, t parameter, number of resected nodes, and vascular or lymphatic invasion, was found be an independent significant predictor of disease-specific and disease-free survival. In contrast, each molecular marker predicted survival and recurrence rates much better than the conventional Dukes staging system. The best combination of variables for prediction of long-term outcome and recurrence rate included p27, p53, and vascular endothelial growth factor. Interestingly, the greater the number of molecular alterations, the lower the five-year estimated survival function. Nearly all cancer-related deaths were observed among patients whose colon cancers expressed all three molecular alterations. Regardless of Dukes stage, the recurrence rate was found to increase with the increase in the number of molecular alterations. Early-stage colon cancers expressing p27 down-regulation and high p53 and vascular endothelial growth factor immunoreactivity showed a 100 percent actuarial four-year recurrence rate.

CONCLUSIONS

Assessment of molecular alterations may be useful to identify a higher-risk group of early-stage colon cancer patients who may benefit from adjuvant chemotherapy.

An analysis of p53, BAX and vascular endothelial growth factor expression in node-positive rectal cancer. Relationships with tumour recurrence and event-free survival of patients treated with adjuvant chemoradiation

Tumours of patients with node-positive rectal cancer were studied by immunohistochemistry for p53, BAX and vascular endothelial growth factor expressions. Results were correlated to the relapse rate, the pattern of relapse and the event-free survival after radical surgery and adjuvant chemoradiation. After a median follow-up of 60 months, 39 patients remained disease-free and 40 patients relapsed (18 local relapses and 22 distant metastases). The majority of disease-free patients showed p53 negative and vascular endothelial growth factor negative tumours. Local relapses occurred more frequently in patients with p53 overexpressing tumours (P<0.01), while distant metastases were in patients with vascular endothelial growth factor positive tumours (P<0.003). Patients with p53 negative or vascular endothelial growth factor negative tumours showed better event-free survival than patients with p53 positive or vascular endothelial growth factor positive tumours. BAX analysis did not show any association with patients' outcome and it was unrelated to the p53 status. Adjuvant treatment strategies for node-positive rectal cancer may be improved by identifying categories of high-risk patients. In this study, vascular endothelial growth factor and p53 expressions correlated with recurrent disease, pattern of relapse and poor event-free survival.

Vascular endothelial growth factor expression, S-phase fraction and thymidylate synthase quantitation in node-positive colon cancer: relationships with tumor recurrence and resistance to adjuvant chemotherapy

BACKGROUND

The behaviour of colorectal carcinomas may depend on molecular properties of tumors. In node-positive colon cancer, we assessed the S-phase fraction (SPF) index, the vascular endothelial growth factor (VEGF) expression and the TS levels. The combined analysis of SPF/VEGF was studied for predictivity of recurrent disease, the TS quantitation was related to the efficacy of fluorouracil-based adjuvant chemotherapy.

PATIENTS AND METHODS

Consecutive patients with surgically-resected, node-positive colon cancer were studied. Flow cytometry for the SPF and immunohistochemistries for the TS and the VEGF expression were carried out on the primary tumor. Recurrences had to be proven by biopsy or surgery, and they were categorized as early, if occurred within 12 months after surgery, or late if occured 13 months or more.

RESULTS

Of 150 evaluable patients, 100 had received fluorouracil-based adjuvant chemotherapy and 50 control patients were untreated. The combined analysis of the VEGF and the SPF showed a strong association between the two markers; 48 patients (32%) had high SPF/VEGF positive tumors and 69 patients (46%) had low SPF/VEGF negative tumors (P < 0.0001). The majority of disease-free patients (73.4%) showed VEGF negative/low SPF tumors (P < 0.0001). Early recurrences occurred more frequently in patients with VEGF positive/high SPF tumors (P < 0.001). In the 100 patients treated with adjuvant chemotherapy, 86% of relapsed patients had TS overexpressing tumors and 69% of disease-free patients had TS negative tumors (P < 0.001). Also, early recurrences occurred more frequently in TS overexpressing tumors (P < 0.0001).

CONCLUSIONS

Evidence is supported that node-positive colon cancer constitutes a heterogenous disease. Patients with VEGF positive/high SPF tumors showed an unfavourable outcome compared to patients with VEGF negative/low SPF tumors. The efficacy of fluorouracil-based adjuvant chemotherapy may depend on the TS status.

Combined modality therapy of rectal cancers

Rectal cancer accounts for about 10% of new cancer cases each year. It strikes men and women at nearly the same rate, generally in the range of 50-80 years of age, with rising incidence with age. Despite simple screening procedures rectal cancer is often advanced when discovered. Current trends in the management of cancer have focused on organ preservation and improved quality of life without compromising the overall survival. During the last decade substantial progress has been made in treatment modalities: new and improved radiation techniques (conformal radiotherapy, altered fractionation, brachytherapy), chemotherapy (protracted infusion, use of radiosensitizers) and development of surgical procedures-enabling safer postoperative irradiation. In patients with advanced/unresectable disease aggressive combined chemoradiation can be added prior to surgery to downstage the tumour and increase the proportion treated with anal-rectal-sparing procedures. Preoperative chemoradiation therapy regimens are as safe and tolerable as the standard postoperative treatment. In this presentation indications for preoperative radiochemotherapy will be discussed in detail, together with treatment-related side effects, prognostic parameters, tumour response and outcome. Different irradiation settings and chemotherapy schedules are described. In patients with primary resectable disease (mainly Dukes C) several prospective randomised trials have shown less local recurrence with postoperative combined modality therapy.

Microsatellite instability and 8p allelic imbalance in stage B2 and C colorectal cancers

BACKGROUND

Microsatellite instability (MSI) and allelic imbalance involving chromosome arms 5q, 8p, 17p, and 18q are genetic alterations commonly found in colorectal cancer. We investigated whether the presence or absence of these genetic alterations would allow stratification of patients with Astler-Coller stage B2 or C colorectal cancer into favorable and unfavorable prognostic groups.

METHODS

Tumors from 508 patients were evaluated for MSI and allelic imbalance by use of 11 microsatellite markers located on chromosome arms 5q, 8p, 15q, 17p, and 18q. Genetic alterations involving each of these markers were examined for associations with survival and disease recurrence. All P values are two-sided.

RESULTS

In univariate analyses, high MSI (MSI-H), i.e., MSI at 30% or more of the loci examined, was associated with improved survival (P =.02) and time to recurrence (P =.01). The group of patients whose tumors exhibited allelic imbalance at chromosome 8p had decreased survival (P =.02) and time to recurrence (P =.004). No statistically significant associations with survival or time to recurrence were observed for markers on chromosome arms 5q, 15q, 17p, or 18q. In multivariate analyses, MSI-H was an independent predictor of improved survival (hazard ratio [HR] = 0.51; 95% confidence interval [CI] = 0.31-0.82; P =.006) and time to recurrence (HR = 0.42; 95% CI = 0.24-0.74; P =.003), and 8p allelic imbalance was an independent predictor of decreased survival (HR = 1.89; 95% CI = 1.25-2.83; P =. 002) and time to recurrence (HR = 2.07; 95% CI = 1.32-3.25; P =.002).

CONCLUSIONS

Patients whose tumors exhibited MSI-H had a favorable prognosis, whereas those with 8p allelic imbalance had a poor prognosis; both alterations served as independent prognostic factors. To our knowledge, this is the first report of an association between 8p allelic imbalance and survival in patients with colorectal cancer.

Biological considerations with pelvic neoplasms

The strategy of therapy for any neoplasm is determined to a significant degree by the biological characteristics of the neoplasm. The ones benefited most by surgical ablation are the cancers that grow locally but never metastasize. The second group is composed of neoplasms with exceedingly slow growth rates permitting long periods of symptom-free survival before recidivation. Many such cancers occur in pelvic structures requiring understanding of the nature of the cancers and then techniques necessary for their resection. The review provides an introduction to some of the relevant biological considerations.

Is early post-operative treatment with 5-fluorouracil possible without affecting anastomotic strength in the intestine?

Early post-operative local or systemic administration of 5-fluorouracil (5-FU) is under investigation as a means to improve outcome after resection of intestinal malignancies. It is therefore quite important to delineate accurately its potentially negative effects on anastomotic repair. Five groups (n = 24) of rats underwent resection and anastomosis of both ileum and colon: a control group and four experimental groups receiving daily 5-FU, starting immediately after operation or after 1, 2 or 3 days. Within each group, the drug (or saline) was delivered either intraperitoneally (n = 12) or intravenously (n = 12). Animals were killed 7 days after operation and healing was assessed by measurement of anastomotic bursting pressure, breaking strength and hydroxyproline content. In all cases, 5-FU treatment from the day of operation or from day 1 significantly (P<0.025) and severely suppressed wound strength; concomitantly, the anastomotic hydroxyproline content was reduced. Depending on the location of the anastomosis and the route of 5-FU administration, even a period of 3 days between operation and first dosage seemed insufficient to prevent weakening of the anastomosis. The effects of intravenous administration, though qualitatively similar, were quantitatively less dramatic than those observed after intraperitoneal delivery. Post-operative treatment with 5-FU, if started within the first 3 days after operation, is detrimental to anastomotic strength and may compromise anastomotic integrity.