Adjuvant therapy for colorectal cancer. The EORTC experience and a review of the literature

Advances and Insights of APC-Asef Inhibitors for Metastatic Colorectal Cancer Therapy

In Colorectal cancer (CRC), adenomatous polyposis coli (APC) directly interacts with the Rho guanine nucleotide exchange factor 4 (Asef) and releases its GEF activity. Activated Asef promotes the aberrant migration and invasion of CRC cell through a CDC42-mediated pathway. Knockdown of either APC or Asef significantly decreases the migration of CRC cells. Therefore, disrupting the APC-Asef interaction is a promising strategy for the treatment of invasive CRC. With the growth of structural information, APC-Asef inhibitors have been designed, providing hope for CRC therapy. Here, we will review the APC-Asef interaction in cancer biology, the structural complex of APC-Asef, two generations of peptide inhibitors of APC-Asef, and small molecule inhibitors of APC-Asef, focusing on research articles over the past 30 years. We posit that these advances in the discovery of APC-Asef inhibitors establish the protein-protein interaction (PPI) as targetable and provide a framework for other PPI programs.

Recurrence Risk after Radical Colorectal Cancer Surgery-Less Than before, But How High Is It?

Simple Summary

Evidence indicates that recurrence risk after colon cancer today is less than it was when trials performed decades ago showed that adjuvant chemotherapy reduces the risk and prolong disease-free and overall survival. After rectal cancer surgery, local recurrence rates have decreased but it is unclear if systemic recurrences have. After a systematic review of available literature reporting recurrence risks after curative colorectal cancer surgery we report that the risks are lower today than they were in the past and that this risk reduction is not solely ascribed to the use of adjuvant therapy. Adjuvant therapy always means overtreatment of many patients, already cured by the surgery. Fewer recurrences mean that progress in the care of these patients has happened but also that the present guidelines giving recommendations based upon old data must be adjusted. The relative gains from adding chemotherapy are not altered, but the absolute number of patients gaining is less.

Abstract

Adjuvant chemotherapy aims at eradicating tumour cells sometimes present after radical surgery for a colorectal cancer (CRC) and thereby diminish the recurrence rate and prolong time to recurrence (TTR). Remaining tumour cells will lead to recurrent disease that is usually fatal. Adjuvant therapy is administered based upon the estimated recurrence risk, which in turn defines the need for this treatment. This systematic overview aims at describing whether the need has decreased since trials showing that adjuvant chemotherapy provides benefits in colon cancer were performed decades ago. Thanks to other improvements than the administration of adjuvant chemotherapy, such as better staging, improved surgery, the use of radiotherapy and more careful pathology, recurrence risks have decreased. Methodological difficulties including intertrial comparisons decades apart and the present selective use of adjuvant therapy prevent an accurate estimate of the magnitude of the decreased need. Furthermore, most trials do not report recurrence rates or TTR, only disease-free and overall survival (DFS/OS). Fewer colon cancer patients, particularly in stage II but also in stage III, today display a sufficient need for adjuvant treatment considering the burden of treatment, especially when oxaliplatin is added. In rectal cancer, neo-adjuvant treatment will be increasingly used, diminishing the need for adjuvant treatment.

Medical Management of Colorectal Carcinomas

Current information on the medical treatment of colorectal cancer was reviewed after a search of the literature through Medline. Publications from 1984 to present were surveyed. Appropriate adjuvant therapy increases overall survival and disease-free intervals. The treatment modalities of unresectable or metastatic tumors are disappointing, with at best 40% of patients experiencing short-lasting responses. Whenever possible, patients with advanced colorectal cancer should be enrolled in clinical trials.

Adjuvant therapy for completely resected stage II colon cancer

BACKGROUND

Colon cancer is potentially curable by surgery. Although adjuvant chemotherapy benefits patients with stage III disease, there is uncertainty of such benefit in stage II colon cancer. A systematic review of the literature was performed to better define the potential benefits of adjuvant therapy for patients with stage II colon cancer.

OBJECTIVES

To determine the effects of adjuvant therapy on overall survival and disease-free survival in patients with stage II colon cancer.

SEARCH STRATEGY

Ovid MEDLINE (1986-2007), EMBASE (1980-2007), and EBM Reviews - Cochrane Central Register of Controlled Trials ( to 2007) were searched using the medical headings "colonic neoplasms", "colorectal neoplasms", "adjuvant chemotherapy", "adjuvant radiotherapy" and "immunotherapy", and the text words "colon cancer" and "colonic neoplasms". In addition, proceedings from the annual meetings of the American Society of Clinical Oncology and the European Society of Medical Oncology (1996 to 2004) as well as personal files were searched for additional information.

SELECTION CRITERIA

Randomized trials or meta-analyses containing data on stage II colon cancer patients undergoing adjuvant therapy versus surgery alone.

DATA COLLECTION AND ANALYSIS

:Three reviewers summarized the results of selected studies. The main outcomes of interest were overall and disease-free survival, however, data on toxicity and treatment delivery were also recorded.

MAIN RESULTS

With regards to the effect of adjuvant therapy on stage II colon cancer, the pooled relative risk ratio for overall survival was 0.96 (95% confidence interval 0.88, 1.05). With regards to disease-free survival, the pooled relative risk ratio was 0.83 (95% confidence interval 0.75, 0.92).

AUTHORS' CONCLUSIONS

Although there was no improvement in overall survival in the pooled analysis, we did find that disease-free survival in patients with stage II colon cancer was significantly better with the use of adjuvant therapy. It seems reasonable to discuss the benefits of adjuvant systemic chemotherapy with those stage II patients who have high risk features, including obstruction, perforation, inadequate lymph node sampling or T4 disease. The co-morbidities and likelihood of tolerating adjuvant systemic chemotherapy should be considered as well. There exists a need to further define which high-risk features in stage II colon cancer patients should be used to select patients for adjuvant therapy. Also, researchers must continue to search for other therapies which might be more effective, shorter in duration and less toxic than those available today.

Prognostic Factors Affecting Locally Recurrent Rectal Cancer and Clinical Significance of Hemoglobin

PURPOSE

To investigate potential prognostic factors, including hemoglobin levels before and during radiotherapy, for associations with survival and local control in patients with unirradiated locally recurrent rectal cancer.

PATIENTS AND METHODS

Ten potential prognostic factors were investigated in 94 patients receiving radiotherapy for recurrent rectal cancer: age (<or=68 vs. >or=69 years), gender, Eastern Cooperative Oncology Group performance status (0-1 vs. 2-3), American Joint Committee on Cancer (AJCC) stage (<or=II vs. III vs. IV), grading (G1-2 vs. G3), surgery, administration of chemotherapy, radiation dose (equivalent dose in 2-Gy fractions: <or=50 vs. >50 Gy), and hemoglobin levels before (<12 vs. >or=12 g/dL) and during (majority of levels: <12 vs. >or=12 g/dL) radiotherapy. Multivariate analyses were performed, including hemoglobin levels, either before or during radiotherapy (not both) because these are confounding variables.

RESULTS

Improved survival was associated with better performance status (p<0.001), lower AJCC stage (p=0.023), surgery (p=0.011), chemotherapy (p=0.003), and hemoglobin levels>or=12 g/dL both before (p=0.031) and during (p<0.001) radiotherapy. On multivariate analyses, performance status, AJCC stage, and hemoglobin levels during radiotherapy maintained significance. Improved local control was associated with better performance status (p=0.040), lower AJCC stage (p=0.010), lower grading (p=0.012), surgery (p<0.001), chemotherapy (p<0.001), and hemoglobin levels>or=12 g/dL before (p<0.001) and during (p<0.001) radiotherapy. On multivariate analyses, chemotherapy, grading, and hemoglobin levels before and during radiotherapy remained significant. Subgroup analyses of the patients having surgery demonstrated the extent of resection to be significantly associated with local control (p=0.011) but not with survival (p=0.45).

CONCLUSION

Predictors for outcome in patients who received radiotherapy for locally recurrent rectal cancer were performance status, AJCC stage, chemotherapy, surgery, extent of resection, histologic grading, and hemoglobin levels both before and during radiotherapy.

Pre-operative radiotherapy and curative surgery for the management of localized rectal carcinoma

BACKGROUND

Preoperative radiotherapy (PRT) has become part of standard practice offered to improve treatment outcomes in patients with rectal cancer.

OBJECTIVES

To determine if PRT improves outcome for patients with localized resectable rectal cancer and how it compared with other adjuvant or neoadjuvant strategies.

SEARCH STRATEGY

A computerized search was performed December 2006 on MEDLINE (from 1966 to December 2006) and the Cochrane Central Register of Controlled Trials (CENTRAL), conference proceedings, using MeSH and textwords where appropriate to identify randomized trials in PRT and rectal cancer. In addition, MetaRegister of Clinical Trials was searched for ongoing trials.

SELECTION CRITERIA

Randomized trials with a PRT arm versus surgery alone, or other neoadjuvant or adjuvant (NA/A) strategies, targeted patients with localized rectal cancer planned for radical surgery were included.

DATA COLLECTION AND ANALYSIS

Trials were selected, data extracted and quality assessed by 2 authors. Quality was assessed using a 14 point checklist. Summary statistics included Hazard ratios and variances (for the outcomes: overall (OA) mortality, cause specific (CS) mortality, any recurrence and local recurrences (LR)) and Odds Ratio (OR) for other outcomes. Potential sources of heterogeneity hypothesized a priori included study quality, biological effective dose (BED), radiotherapy RT technique, and total mesorectal excision (TME) surgery.

MAIN RESULTS

Nineteen trials compared PRT versus surgery alone. Overall (OA) mortality was marginally improved HR 0.93 [95% CI -0.87-1](absolute difference is 2% if the expected survival rate is 60%). Local recurrence (LR) was improved but the magnitude of benefit was heterogeneous across trials. Sensitivity analyses suggested greater benefits in patients treated with BED>30Gy(10) and multiple field RT techniques. There was significantly more pelvic or perineal wound infection, late rectal and sexual dysfunction. Nine trials compared PRT vs. other NA/A. Available evidence did not support an OA mortality or sphincter preserving benefit with the use of combined chemoradiotherapy (CRT) or selective postoperative RT. CRT provides incremental benefit for local control compared with PRT, which was independent of the timing of the CT. There was no significant difference in outcome for different intervals between RT and surgery (2 vs. 8 wk). Dose escalation with endocavitary boost showed significant effect on sphincter preservation.

AUTHORS' CONCLUSIONS

Optimal PRT improves LR, OA mortality, but no increase in sphincter sparing procedure. CRT further increases local control. If the objective is to increase the incidence of sphincter sparing surgery, endocavitary boost showed the most promise. Strategies with the potential to improve outcomes, especially OAS and sphincter sparing while reducing acute and late toxicities (rectal and sexual function) are needed to guide future strategy designs.

Intestinal permeability in humans is increased after radiation therapy

PURPOSE

Irradiation inflicts acute injuries to the intestinal mucosa with rapid apoptosis induction and subsequent reduction in epithelial surface area. It may therefore be assumed that the intestinal barrier function is affected. The aim of this study was to compare the mucosal permeability in irradiated rectum and nonirradiated sigmoid colon from patients subjected to radiation therapy before surgical treatment for rectal cancer.

METHODS

Segments from sigmoid colon and rectum obtained from irradiated and nonirradiated patients were stripped from the serosa-muscle layer and mounted in Ussing diffusion chambers. The mucosa-to-serosa passage of the marker molecules 14C-mannitol, fluorescein isothiocyanate-dextran 4,400, and ovalbumin was followed for 120 minutes.

RESULTS

The permeability to the markers was size-dependent and increased linearly across time in all specimens. The passage of all markers was increased in irradiated rectum compared with nonirradiated sigmoid colon, whereas in specimens from nonirradiated patients there were no differences between rectum and sigmoid colon. Histologic signs of crypt and mucosal atrophy were found in the irradiated rectal specimens.

CONCLUSIONS

Early gastrointestinal complications after radiation therapy may be the result of mucosal atrophy in addition to mucosal damage, with a loss of barrier integrity.

Electrochemical lesions in the rat liver support its potential for treatment of liver tumors

BACKGROUND

An effective therapy is needed for patients with surgically unresectable liver tumors who have very limited life expectancy. One possible treatment is electrochemical tumor necrosis. This study investigated the natural history of electrochemical lesions in the normal rat liver.

MATERIALS AND METHODS

A direct current generator, connected to platinum electrodes, was used to create controlled areas of liver necrosis. Animals were sacrificed 2 days, 2 weeks, 2 months, and 6 months after treatment and the macroscopic and histological appearance of the necrotic lesions was followed.

RESULTS

No animal died as a result of electrolysis; postoperatively, all gained weight normally. Liver enzymes were significantly (P < 0.001) elevated after treatment, but returned to normal after a week. Two days after electrolysis, histology confirmed an ellipsoidal area of coagulative necrosis at the site of the electrode tip and commonly a segment of peripheral necrosis. After 2 weeks there was histological evidence of healing. By 6 months, very little necrotic tissue remained within a small fibrous scar.

CONCLUSIONS

Electrolysis is a safe method for creating defined areas of liver necrosis that heal well with no associated mortality. This study supports the potential of electrolysis for treating patients with unresectable liver tumors.

Experimental study of the effect of preoperative 5-fluorouracil on the integrity of colonic anastomoses

BACKGROUND

Despite curative resection for colorectal cancer, many patients develop recurrence at the primary site or distant organs. These patients are candidates for (neo)-adjuvant chemotherapy. Very little is known about the effect of preoperative 5-fluorouracil (FU) on the healing of colonic anastomoses. The aim of this study was to assess this in a rat model.

METHODS

Eighty male Wistar rats, weighing 160-215 g, were divided into three groups; (1) a control group underwent left colon resection and primary anastomosis (n = 20); (2) a sham group received 1 ml saline intraperitoneally (n = 30); (3) a study group received 5-FU intraperitoneally (20 mg kg-1). Both saline and 5-FU injections were given intraperitoneally for 5 days before operation.

RESULTS

There was no difference in the rate of wound complications, intraperitoneal adhesions and anastomotic complications among the groups. Three and seven days after operation, mean bursting pressure of the anastomosis was 36.5 and 198 mmHg in group 1, 34 and 200 mmHg in group 2, and 39 and 190 mmHg in group 3 respectively (P not significant). Although the myeloperoxidase and hydroxyproline content were significantly lower after 5-FU therapy (P < 0.01, compared with others), the clinical outcome was similar.

CONCLUSION

Preoperative 5-FU consecutive days before operation had no effect on the healing of colonic anastomoses.

Experimental colonic healing in relation to timing of 5-fluorouracil therapy

In an experimental study resembling clinical use of adjuvant 5-fluorouracil (5-FU) treatment of colorectal carcinoma, 97 male Wistar rats were operated on with a standardized left colonic resection. Treatment was given as a daily intraperitoneal injection. The animals were randomized to one of four groups: early treatment with 5-FU 20 mg/kg or saline 0.1 mol/l from the day of operation to day 7 after operation, and delayed treatment with 5-FU 20 mg/kg or saline 0.1 mol/l from the third day after operation to the day before killing. The animals were killed in groups on day 7 or 10 after operation. In the group receiving early 5-FU treatment there was an increased rate of anastomotic complications (seven of 26) compared with none in the control or delayed 5-FU groups. The anastomotic breaking strength in animals having early 5-FU treatment (day 7, median 1.45 (range 0.20-2.95) N; day 10, median 1.80 (range 0.95-3.20) N) was significantly lower than that in controls on both day 7 (median 3.20 (range 2.50-3.80)N) and day 10 (median 3.20 (range 2.20-3.60)N). In the delayed 5-FU treatment group anastomotic breaking strength did not differ from that in controls. Colonic healing was not impaired when intraperitoneal 5-FU treatment was started on day 3 after operation, whereas immediate postoperative administration of 5-FU had a detrimental effect on wound healing.

Long-term results of a randomised trial of short-course low-dose adjuvant pre-operative radiotherapy for rectal cancer: reduction in local treatment failure

A prospective randomised multicentre trial compared pre-operative radiotherapy followed by surgery with surgery alone for rectal cancer < or = 12 cm from the anal verge. Of 468 patients (mean age 67 years, range 31-94, 273 males) who met the entry criteria, 228 were randomised to radiotherapy (3 x 5 Gy over 5 days within 2 days of operation) followed by surgery, and 239 to surgery alone. Randomisation was unknown in 1 patient. Follow-up to death or 5 years was achieved in 454 (97%) patients. 31 (7%) of the 468 patients died within 30 days of operation (radiotherapy and surgery 21 [9%], surgery alone 10 [4%]; P < 0.05). Cardiovascular and thromboembolic complications were more common after radiotherapy and surgery (30, 13%) than after surgery alone (8, 3%; P < 0.005). Of the 280 patients who had curative surgery, 52% of those who had radiotherapy and surgery and 56% of those who had surgery alone survived 5 years (P = 0.88). 395 patients attended outpatients clinics at least once. Local treatment failure was identified during follow-up in 82 patients [31/185 (17%) radiotherapy and surgery; 51/210 (24%) surgery alone; P < 0.05]. It occurred in 33 of the 258 patients who had a curative resection and attended outpatients [radiotherapy and surgery, 11/120 (9%), surgery alone, 22/138 (16%); P = 0.08]. Long-term survival was unaffected, but long-term local recurrence was reduced by the addition of low-dose radiotherapy to surgery. Peri-operative mortality was, however, increased.

Radiation effects in the colon. An experimental study in the rat

In an experimental study, resembling a clinical trial of preoperative irradiation, 10 + 10 Gy was given to the pelvic and lower abdominal region of rats with a 4-day interval. The early effect on the colonic wall was evaluated by myeloperoxidase activity and hydroxyproline content of the bowel wall and correlated to histological findings. Groups of animals were followed up to eight months after irradiation for evaluation of later effects. General effects of irradiation were seen as low WBC during the first week and delayed body weight development up to two months after irradiation. Local effect in the colonic wall was noted as an increase in myeloperoxidase activity (indicating a leucocyte accumulation) in irradiated parts of colon during the first 11 days and again significantly elevated after two months in parts of colon, irradiated as well as protected. This correlated well with histological findings of inflammatory reaction, atypia and dysplasia during the first 10 days after irradiation but not at two months after irradiation. Hydroxyproline content was not affected. There were no major complications due to irradiation seen in the late course of the study period.

Influence of 5-fluorouracil and folinic acid on colonic healing: an experimental study in the rat

Male Wistar rats were subjected to colonic resection and randomized to one of four groups: control group (intraperitoneal NaCl, intravenous NaCl); 5-fluorouracil (5-FU) group (intraperitoneal 5-FU, intravenous NaCl); folinic acid group (intraperitoneal NaCl, intravenous folinic acid); and 5-FU-folinic acid group (intraperitoneal 5-FU, intravenous folinic acid). Treatment was started immediately after surgery and continued until the animals were killed at 3 or 7 days. Anastomotic complications (abscesses or dehiscence) occurred in four of 33 animals in the control group, 12 of 36 in the 5-FU group, one of 32 in the folinic acid group and nine of 36 in the 5-FU-folinic acid group. Anastomotic and skin breaking strength did not differ between groups on day 3 but by day 7 were significantly reduced in the 5-FU group. In rats given 5-FU-folinic acid, breaking strength was also reduced, but less so than in the 5-FU group. Breaking strength in animals receiving folinic acid was similar to that in the control group. In this model colonic healing was impaired after intraperitoneal 5-FU administration, but when folinic acid was added no further deterioration occurred.

Low-dose preoperative radiation postpones recurrences in operable rectal cancer. Results of a randomized multicenter trial in western Norway

A randomized, multicenter clinical trial was conducted in Western Norway to study the effectiveness of preoperative radiation therapy in operable rectal cancer, given at a dosage of 3150 cGy in 18 fractions, 2 to 3 weeks before radical surgery. Three hundred nine patients were entered into the trial between May 1976 and December 1985. After radiation no tumor was seen in 4.5% of the patients. There was no increased morbidity or mortality at surgery. The 5-year survival for evaluable patients was 57.5% in the control group and 56.7% in the radiotherapy group. For patients operated on for cure the 5-year survival was 60.9% and 64.2% in the control group and radiotherapy group, respectively. Radiation significantly delayed both local and distant recurrences in patients in the radiation group who had curative resection from 13.3 months in controls to 27.1 months. The local recurrence rate in the corresponding groups was 21.1% and 13.7%, respectively. We conclude that higher preoperative radiation doses should be used in new trials as a higher dosage may transform the observed positive effects into a survival benefit.

Resection of hepatic metastases from colorectal cancer. Biologic perspective

During the past decade the results of slightly fewer than 1000 resections of liver metastases from colorectal carcinoma have been analyzed, retrospectively reanalyzed, and reviewed. The following are confirmed conclusions: major liver resection can be performed safely (less than a 5% operative mortality rate); 20% to 25% of these patients are cured; no other regional therapy options have any curative potential. The following caveats are also obvious: most patients who are operated on are not cured; although predictors have been proposed to select patients most likely to benefit from surgery, none is discriminating in and of itself; most therapy questions in this group of patients have not been addressed in any formal way; surgery for isolated regionally recurrent colon and rectum carcinoma remains an important stopgap only until effective systemic therapy is discovered. This review of our own and other single and multi-institutional prospective and retrospective data will be framed by the following questions. (1) Does resection of liver metastases cure patients or simply select those who would have survived in the long-term without any therapy? (2) In the absence of any formalized, properly designed trial, how can one judge the benefit of resection? (3) Why do metastases recur only in the liver? (4) What new therapies should focus on the predominant secondary failure sites in the majority of patients who do not benefit from hepatic metastasis resection?

Lymphokine-activated killer cell activity in patients with primary and metastatic malignant liver tumors

Lymphokine-activated killer cells were generated from peripheral blood mononuclear cells of 33 patients with liver tumors (benign, 6; primary malignant, 10; metastatic, 17) and 10 healthy individuals. Although peripheral blood mononuclear cell yield was significantly lower (p less than 0.01) in patients with hepatocellular carcinoma or with metastatic colorectal cancer, natural killer activity in the peripheral blood mononuclear cell fraction was comparable in all groups tested. Optimal lymphokine-activated killer activity was demonstrated after 9 to 12 days of culture in recombinant interleukin 2. Lymphokine-activated killer activity, interleukin 2-induced lymphocyte proliferation and total lytic activity generated per culture in all patient groups studied were similar to those of normal control cells cultured under the same conditions. These in vitro data demonstrate the feasibility of obtaining lymphokine-activated killer cells from the blood of patients with liver tumors and provide a rationale for the future use of lymphokine-activated killer cells in adoptive immunotherapy of patients with primary and metastatic hepatic neoplasms.

Unimpaired ability to generate adherent lymphokine-activated killer (A-LAK) cells in patients with primary or metastatic liver tumors

Adherent lymphokine-activated killer cells (A-LAK cells) obtained from human peripheral blood mononuclear cells represent a population of potent antitumor effectors enriched in interleukin-2(IL-2)-activated natural killer cells. This study shows that A-LAK cells can be successfully generated from the blood of patients with liver cancer not treated with adjuvant chemotherapy or irradiation. Mononuclear cells were isolated from the blood of 33 patients with liver tumors (6 benign, 10 primary malignant, 17 metastatic) at the time of liver resection. A-LAK cells were separated by adherence to plastic following activation of peripheral blood mononuclear cells in 1000 U/ml recombinant IL-2. A-LAK cells (enriched up to 92% in CD3-CD56+ cells) showed better subsequent expansion and two to six times higher antitumor cytotoxicity per cell than unseparated LAK cells cultured under the same conditions. The ability to generate A-LAK cells with superior in vitro cytotoxicity from the blood of most patients with liver cancer indicates that adoptive cellular immunotherapy may be a feasible and new way of treatment for primary and secondary hepatic neoplasms in man.

Endoluminal ultrasound and computed tomography in the staging of rectal cancer

Pre-operative staging of rectal cancer might define patients with disease confined to the rectal wall without lymph node metastases, in whom local excision might be appropriate, or patients with extrarectal spread, who might benefit from pre-operative radiotherapy. With these objectives, 36 consecutive patients with rectal cancer were studied by endoluminal ultrasound: 17 of them also underwent computed tomography (CT) of the pelvis. The results were correlated with the findings at operation and subsequent pathological examination. Endoluminal ultrasound correctly predicted invasion of the tumour through the rectal wall in 86 per cent of patients, with a sensitivity of 96 per cent and specificity of 50 per cent, but correctly identified lymph node metastases in only 61 per cent of patients (sensitivity 57 per cent; specificity 64 per cent). CT correctly predicted invasion through the rectal wall in 94 per cent of cases, with a sensitivity of 100 per cent and specificity of 67 per cent and correctly identified lymph node metastases in 70 per cent of patients (sensitivity 25 per cent; specificity 85 per cent). These findings indicate that both endoluminal ultrasound and CT may be helpful in selecting patients for pre-operative radiotherapy. Neither technique, however, can reliably identify lymph node metastases and therefore cannot be used to select patients who would be suitable for local excision.