The Risk of Distant Metastases in Patients With Clinical Complete Response Managed by Watch and Wait After Neoadjuvant Therapy for Rectal Cancer: The Influence of Local Regrowth in the International Watch and Wait Database

BACKGROUND

Nearly 30% of patients with rectal cancer develop local regrowth after initial clinical complete response managed by watch and wait. These patients might be at higher risk for distant metastases.

OBJECTIVE

This study aimed to investigate risk factors for distant metastases using time-dependent analyses.

DESIGN

Data from an international watch and wait database were retrospectively reviewed. Cox regression analysis was used to determine risk factors for worse distant metastases-free survival. Conditional survival modeling was used to investigate the impact of risk factors on the development of distant metastases.

SETTING

Retrospective, multicenter database.

PATIENTS

A total of 793 patients (47 institutions) with rectal cancer and clinical complete response to neoadjuvant treatment from the International Watch & Wait Database were included.

MAIN OUTCOME MEASURES

Distant metastases-free survival.

RESULTS

Of the 793 patients managed with watch and wait (median follow-up 55.2 mo)' 85 patients (10.7%) had distant metastases. Fifty-one of 85 patients (60%) had local regrowth at any time. Local regrowth was an independent factor associated with worse distant metastases-free survival in the multivariable model. Using conditional estimates, patients with local regrowth without distant metastases for 5 years (from decision to watch and wait) remained at higher risk for development of distant metastases for 1 subsequent year compared to patients without local regrowth (5-year conditional distant metastases-free survival 94.9% vs 98.4%).

LIMITATIONS

Lack of information on adjuvant chemotherapy, salvage surgery for local regrowth, and heterogeneity of individual surveillance/follow-up strategies used may have affected results.

CONCLUSIONS

In patients with clinical complete response managed by watch and wait, development of local regrowth at any time is a risk factor for distant metastases. The risk of distant metastases remains higher for 5 years after development of local regrowth. See Video Abstract at http://links.lww.com/DCR/C53.

EL RIESGO DE METSTASIS A DISTANCIA EN PACIENTES CON RESPUESTA CLNICA COMPLETA MANEJADA POR WATCH AND WAIT DESPUS DE LA TERAPIA NEOADYUVANTE PARA EL CNCER DE RECTO LA INFLUENCIA DEL NUEVO CRECIMIENTO LOCAL EN LA BASE DE DATOS INTERNACIONAL WATCH AND WAIT

ANTECEDENTES:Casi el 30 % de los pacientes con cáncer de recto desarrollan un nuevo crecimiento local después de la respuesta clínica completa inicial manejada por watch and wait. Estos pacientes podrían tener un mayor riesgo de metástasis a distancia.OBJETIVO:Investigar los factores de riesgo de metástasis a distancia mediante análisis dependientes del tiempo.DISEÑO:Se revisó retrospectivamente los datos de la base de datos internacional de Watch and Wait. Se utilizó el análisis de regresión de Cox para determinar los factores de riesgo de peor sobrevida libre de metástasis a distancia. Se utilizó un modelo de sobrevida condicional para investigar el impacto de los factores de riesgo en el desarrollo de metástasis a distancia. El tiempo transcurrido hasta el evento se calculó utilizando la fecha de decisión para watch and wait y la fecha del nuevo crecimiento local para el diagnóstico de metástasis a distancia.ESCENARIOBase de datos multicéntrica retrospectiva.PACIENTES:Se incluyeron un total de 793 pacientes (47 instituciones) con cáncer de recto y respuesta clínica completa al tratamiento neoadyuvante de la base de datos internacional de Watch and Wait.PRINCIPALES MEDIDAS DE RESULTADO:Desarrollo de metástasis a distancia.RESULTADOS:De los 793 pacientes tratados con watch and wait (mediana de seguimiento de 55,2 meses), 85 (10,7%) tenían metástasis a distancia. 51 de 85 (60%) tuvieron recrecimiento local en algún momento. El recrecimiento local fue un factor independiente asociado a una peor supervivencia libre de metástasis a distancia en el modelo multivariable. Además, al usar estimaciones condicionales, los pacientes con recrecimiento local sin metástasis a distancia durante 5 años (desde la decisión de watch and wait) permanecieron en mayor riesgo de desarrollar metástasis a distancia durante un año subsiguiente en comparación con los pacientes sin recrecimiento local (sobrevida libre de metástasis a distancia a 5 años: recrecimiento local 94,9% frente a no recrecimiento local 98,4%).LIMITACIONES:La falta de información relacionada con el uso de quimioterapia adyuvante, las características específicas de la cirugía de rescate para el nuevo crecimient o local y la heterogeneidad de las estrategias individuales de vigilancia/seguimiento utilizadas pueden haber afectado los resultados observados.CONCLUSIONES:En pacientes con respuesta clínica completa manejados por Watch and Wait, el desarrollo de recrecimiento local en cualquier momento es un factor de riesgo para metástasis a distancia. El riesgo de metástasis a distancia sigue siendo mayor durante 5 años después del desarrollo de un nuevo crecimiento local. Consulte Video Resumen en http://links.lww.com/DCR/C53. (Traducción-Dr. Felipe Bellolio).

Breast cancer index (BCI) predicts benefit of two-and-a-half versus five years of extended endocrine therapy in HR+ breast cancer patients treated in the ideal trial

512

Background: For postmenopausal women with hormone receptor positive (HR+) breast cancer, the optimal duration of extended endocrine therapy (EET), after completing 5 years of initial aromatase inhibitor (AI)–based adjuvant therapy, remains unclear. BCI [HOXB13/IL17BR (H/I)] is a gene expression-based biomarker that has been demonstrated to predict EET benefit in the MA.17 and Trans-aTTom studies in patients treated with adjuvant tamoxifen. The current study examined the ability of BCI (H/I) to predict endocrine benefit from 2.5 vs. 5 years of extended letrozole in the IDEAL trial. Methods: All patients with available tumor specimens were eligible for this blinded prospective-retrospective study. The primary endpoint was Recurrence-Free Interval (RFI). Median follow-up was 9.1 years from randomization. Kaplan-Meier and Cox proportional hazards regression analysis were used to analyze the differential benefit of EET with statistical significance of the interaction between BCI (H/I) and treatment assessed by likelihood ratio test. Results: 908 HR+ patients (73% pN+, median 59y, 45% pT1, 48% pT2, disease free at 2.5 years) were included, with 88% and 68% receiving prior treatment with an AI or chemotherapy, respectively. BCI by H/I status (High vs. Low) was significantly predictive of response from extended letrozole in the overall (N = 908) and pN+ (N = 664) cohorts. Notably, BCI (H/I) predicted EET benefit in patients that received any primary adjuvant therapy with an AI (N = 794). Treatment to biomarker interaction was significant in the overall (p = 0.045), pN+ (p = 0.029) and any prior AI (p = 0.025) cohorts, adjusted for age, pT stage, grade, nodal status, prior endocrine therapy and prior chemotherapy. Conclusions: Novel findings from this study demonstrate that BCI predicts endocrine benefit from extended letrozole in postmenopausal patients treated with primary adjuvant AI. These results support the growing body of evidence that BCI by H/I status predicts preferential endocrine response in distinct subgroups of patients, and further support its role as an important genomic tool to inform the risk-benefit regarding duration of extended endocrine therapy. Clinical trial information: NTR3077, BOOG 2006-05, Eudra-CT 2006-003958-16 . [Table: see text]

Disease-free survival as a surrogate for overall survival in neoadjuvant trials of gastroesophageal adenocarcinoma: Pooled analysis of individual patient data from randomized controlled trials

4533

Background: Disease-free survival (DFS) is an appealing surrogate endpoint for overall survival (OS) in trials on neoadjuvant or adjuvant cancer therapy, because it is available faster and with less follow-up effort. The aim of this study was to assess if DFS can be a valid surrogate endpoint for OS when comparing neoadjuvant treatment followed by surgery to surgery alone for gastroesophageal adenocarcinoma. Methods: Individual patient data (IPD) from eight randomized controlled trials (n = 1,126 patients) which compared neoadjuvant therapy followed by surgery with surgery alone for gastroesophageal adenocarcinoma were used for the analysis. Correlation between OS-time and DFS-time was calculated. Kaplan-Meier survival curves and corresponding hazard ratios (HRs) for treatment effects were separately determined for each trial. Subsequently, HRs were pooled in a meta-analysis using a random-effects model. An error-in-variables linear regression model was used to compare observed and predicted values. The minimum treatment effect on DFS necessary to predict a non-zero treatment effect on OS was estimated by calculating the surrogate threshold effect. Results: OS-time correlated strongly with DFS-time. HRs for OS and DFS were highly similar for all single trials. The meta-analysis yielded almost identical overall HRs for treatment effects on OS and DFS. The determination coefficient for the association between HRs for OS and DFS was 0.912 (95% confidence interval 0.75-1.0), indicating a strong trial-level surrogacy between OS and DFS. The surrogate threshold effect was calculated at 0.79, indicating that a future trial yielding a hazard ratio for the treatment effect on DFS < 0.79 could be expected with a 95% probability to yield a hazard ratio for the treatment effect on OS < 1. Conclusions: DFS and OS strongly correlate both after neoadjuvant therapy followed by surgery and after surgery alone for gastroesophageal adenocarcinoma. Likewise, the treatment effects on the two endpoints are very similar. Consequently, DFS can be regarded an appropriate surrogate endpoint for OS in trials on neoadjuvant therapy for gastroesophageal adenocarcinoma.

Short-course radiotherapy followed by chemotherapy before TME in locally advanced rectal cancer: The randomized RAPIDO trial

4006

Background: Local control in locally advanced rectal cancer (LARC) has improved. However, systemic relapses remain high even with postoperative chemotherapy, possibly due to low compliance. Short-course radiotherapy (SCRT) followed by delayed surgery with, in the waiting period, chemotherapy, may lead to better compliance, downstaging and fewer distant metastases. The main objective of the international multicenter phase III RAPIDO trial is to decrease Disease-related Treatment Failure (DrTF), defined as locoregional failure, distant metastasis, a new primary colon tumor or treatment-related death, by reducing the risk of systemic relapse without compromising local control. Methods: MRI-diagnosed LARC patients with either cT4a/b, extramural vascular invasion, cN2, involved mesorectal fascia or enlarged lateral lymph nodes considered to be metastatic were randomly assigned to SCRT (5x5 Gy) with subsequent six cycles of CAPOX or nine cycles of FOLFOX4 followed by total mesorectal excision (TME) (experimental arm) or, capecitabine-based chemoradiotherapy (25-28 x 2.0-1.8 Gy) followed by TME and optional, predefined by hospital policy, postoperative eight cycles of CAPOX or twelve cycles of FOLFOX4 (standard arm). Results: Between June 2011 and June 2016, 920 patients were randomized. Pathological complete response rates were 27.7% vs 13.8% (OR 2.40 [1.70 – 3.39]; p < 0.001) in the experimental and standard arms, respectively. At three years, cumulative probability of DrTF was 23.7% in the experimental arm and 30.4% in the standard arm (HR 0.76 [0.60 – 0.96]; p = 0.02). Probability at three years of distant metastasis and locoregional failure were, in the experimental and standard arms, 19.8% vs 26.6% (HR 0.69 [0.53 – 0.89]; p = 0.004) and 8.7% vs 6.0% (HR 1.45 [0.93 – 2.25]; p = 0.10), respectively. No differences in DrTF between hospitals with or without policy for postoperative chemotherapy were found (p = 0.37). Overall health ( p = 0.192), quality of life ( p = 0.125) and low anterior resection syndrome score ( p = 0.136) were comparable between the two treatment arms. Conclusions: A lower rate of DrTF, as a result of a lower rate of distant metastases, in high-risk LARC patients can be achieved with preoperative short-course radiotherapy, followed by chemotherapy and TME than by conventional chemoradiotherapy. In addition, the high pCR rate, achieved with the experimental treatment regimen can contribute to organ preservation. This treatment can be considered as a new standard of care. Clinical trial information: NCT01558921 .

Conditional survival of patients with rectal cancer undergoing Watch and Wait: The risk of recurrence over time

30

Background: Patients with rectal cancer and complete clinical response (cCR) after neoadjuvant chemoradiation (nCRT) have been offered non-operative management (W&W). Risk factors for local regrowth (RG) include baseline cT and type of nCRT. However, the influence of risk factors for RG over time and the extent in time that patients need to be followed with the rectum in situ after a cCR are unknown. Objective: Analyze the risk of recurrence over time through conditional survival (cDFS/cLRFS) estimates for rectal cancer patients under W&W. Methods: Retrospective analysis of all patients from the largest multicenter database of patients managed non-operatively (International Watch and Wait Database–IWWD). Only patients with cCR after nCRT and W&W with a median of >3 years of follow-up were included. cDFS was used to investigate the evolution of recurrence-odds, as patients remain disease-free after nCRT. 2-year cDFS was estimated at “x” years after nCRT based on the formula cDFS2=DFS(x+2)/DFS(x). Results: 768 patients treated between 1991-2015 were included. Using cDFSestimates, the probability of remaining disease-free for 2 additional years once cCR was achieved and sustained for 1, 3, and 5 years, were 85%, 97%, and 95%, respectively. These contrast with the actuarial DFS for similar intervals of 70%, 68% and 65% respectively. Baseline cT was associated with the risk of RG at 1 year after a cCR (cT2 aLRFS 89% vs. cT3 82%; p=0.004). However, after sustaining a cCR for 1 year, baseline cT becomes irrelevant at 2 years (cLRFS; 94% vs. 90%; |d| 0.14). Also, total dose of RT (≤50 vs >50Gy) was associated with the risk of RG (aLRFS 76% vs 85%; p=0.03) at 1 year. Dose of RT becomes irrelevant (at 2 years; cLRFS 93% vs. 90%; |d| 0.10) once patients sustained a cCR for 1 year. Conclusions: Conditional survival estimates suggests that patients have significantly lower risks (≤5%) of developing late RG (at 5 years) after sustaining cCR for 3 years. A sustained cCR over time may be more relevant for long-term risk of RG than cT-stage or RT dose. The present data can have significant consequences for the recommendation of intensive surveillance after sustaining 3ys of cCR.

Lateral lymph node dissection after neoadjuvant (chemo)radiotherapy may improve oncological outcomes in Western patients with low rectal cancer

163

Background: In the West, rectal cancer patients with pre-treatment abnormal lateral lymph nodes (LLN) are commonly treated with neoadjuvant (chemo)radiotherapy (n(C)RT) followed by total mesorectal excision (TME). Few centers perform lateral lymph node dissection (LLND) in addition to this, with the aim of improving oncological outcomes. To date, no comparative data are available in Western patients. Methods: An international multi-center cohort study was conducted comparing six centers from the Netherlands and Australia treating patients with abnormal LLN (≥5mm short-axis) with n(C)RT and TME (LLND- group) versus similarly staged patients from a dedicated cancer center in the USA who underwent a LLND in addition to n(C)RT and TME (LLND+ group). Results: Data were available on 169 patients. LLND+ patients (n = 44) consisted of significantly younger and more female patients with higher ASA-scores and ypN-stages compared to LLND- patients (n = 115). LLND+ patients also had a larger median LLN short-axis and were more likely to receive adjuvant chemotherapy (100 vs. 30%; p < 0.0001). Between groups, the lateral local recurrence rate (LLRR) was 0% for LLND+ vs. 7% for LLND- (p = 0.09) and the local recurrence rate (LRR) was 3% for LLND+ vs. 11% for LLND- (p = 0.13). No significant differences were observed in disease-free survival (DFS, p = 0.94) or overall survival (OS, p = 0.42). Sub-analysis of patients who underwent adjuvant chemotherapy (LLND- patients: n = 35) demonstrated clinically relevant though non-statistically significant trends towards a lower LLRR (0% for LLND+ vs. 6% for LLND-; p = 0.07), LRR (3% for LLND+ vs. 14% for LLND-; p = 0.06), DFS (p = 0.19) and OS (p = 0.17) in favour of the LLND+ group. Conclusions: Lateral lymph node dissection in addition to neoadjuvant (chemo)radiotherapy may improve oncological outcomes in Western patients with low rectal cancer and abnormal lateral lymph nodes.

A comparison of elderly versus nonelderly patients in the CRITICS gastric cancer trial

81

Background: Although the proportion of elderly cancer patients (pts) increases, few randomized trials provide separate results on this group. Here, we present a sub-analysis of the CRITICS trial, comparing elderly with non-elderly pts. Methods: Preoperative (preop) chemotherapy (CT) included three cycles of epirubicin, cisplatin/oxaliplatin and capecitabine (ECC/EOC); pts were upfront randomized between postoperative (postop) CT (3x ECC/EOC) and chemoradiotherapy (CRT; 45Gy + cisplatin/capecitabine). Elderly pts were defined as age ≥ 70 years at the time of randomization. We present tolerability and outcomes for elderly versus non-elderly pts. Results: Details on baseline characteristics, preop treatment, surgery, postop treatment and survival are shown in Table 1. Tumor type and localization did not differ between both groups. Conclusions: Age had a significant impact on toxicity and tolerability of preop CT, but did not affect surgical resection rates and complications. Although less elderly pts started postop treatment and elderly pts received lower dose in de CT arm, there were no differences in treatment related toxicities. Survival was not significantly different. Clinical trial information: NCT00407186. [Table: see text]

An international patient-centered outcome measurement set for colorectal cancer

753

Background: While there are tools to measure outcomes relevant to patients with colorectal cancer, none is universally accepted and none incorporates components of long-term clinical outcomes, acute complications, and patient-reported outcomes (PROs). Methods: The International Consortium for Health Outcomes Measurement convened an international multidisciplinary working group to develop a comprehensive patient-centered outcome measurement set for patients with all stages of colorectal cancer. The working group utilized a literature review, patient focus group and their own clinical expertise to reach consensus on outcomes and case mix factors through a modified Delphi process. Measurement tools were selected by International Society of Quality of Life Research standards. The final list of PROs was validated through a patient survey. Results: The 29 members of the working group included patient representatives and palliative care, nursing, pathology, medical oncology, colorectal surgery and radiation oncology specialists from academic and nonacademic practices in Europe, Australia, Asia and the USA. The international focus group included 11 patients with colorectal cancer treated with palliative and curative intents. The working group defined four clinical outcomes applicable to all and eight specific to subgroups, such as presence of ostomy for patients with rectal cancer and hospital admission in the last 30 days of life for patients with advanced disease. An algorithm for documenting acute complications was developed. The working group defined 11 PROs applicable to all and eight specific to subgroups, such as erectile dysfunction for patients who received radiotherapy/surgery and neuropathy for those who received chemotherapy. 276 colorectal cancer patients completed the validation survey. Conclusions: Through use of extensive patient input, the international multidisciplinary group developed a patient-centered outcome measurement set incorporating clinical outcomes, acute complications and PROs for patients with colorectal cancer. This comprehensive measurement set allows for standardized international comparison on quality of care outcomes and will be revised annually.

Stromal Targets for Fluorescent-Guided Oncologic Surgery

Pre-operative imaging techniques are essential for tumor detection and diagnosis, but offer limited help during surgery. Recently, the applicability of imaging during oncologic surgery has been recognized, using near-infrared fluorescent dyes conjugated to targeting antibodies, peptides, or other vehicles. Image-guided oncologic surgery (IGOS) assists the surgeFon to distinguish tumor from normal tissue during operation, and can aid in recognizing vital structures. IGOS relies on an optimized combination of a dedicated fluorescent camera system and specific probes for targeting. IGOS probes for clinical use are not widely available yet, but numerous pre-clinical studies have been published and clinical trials are being established or prepared. Most of the investigated probes are based on antibodies or peptides against proteins on the membranes of malignant cells, whereas others are directed against stromal cells. Targeting stroma cells for IGOS has several advantages. Besides the high stromal content in more aggressive tumor types, the stroma is often primarily located at the periphery/invasive front of the tumor, which makes stromal targets particularly suited for imaging purposes. Moreover, because stroma up-regulation is a physiological reaction, most proteins to be targeted on these cells are “universal” and not derived from a specific genetic variation, as is the case with many upregulated proteins on malignant cancer cells.

Prognostic and predictable value of COX2 expression in Russian women with stage I breast cancer

80

Background: Some previous studies found worse prognosis among cyclooxygenase-2 (COX2)-expressing breast cancers; we study prognostic and predictiable value of COX2 expression in breast cancer stage I. Methods: our study included Russian women with breast cancer stage I (n=315) treated in RCRC, RMAPE (1985-2009). A Tissue Micro Array (TMA) with triplicate 1 mm tumor tissue punches taken from tumor blocks was constructed in LUMC; sections were immunohistochemically stained for ER, PR, HER2-status, Ki67 (by standard morphological criteria); COX2-expression were evaluated as positive (>median; 31/309 cases, 10%) or negative (≤median; 278/209 cases, 90%). Also the histological type, grade, age and adjuvant endocrine therapy were examined. We analyzed the clinic and morphological data of COX2-positive tumors, prognostic value for survival (relapses free- RFS, overall- OS and cancer specific- CSS) and predictable value for endocrine therapy. Results: COX2-positive tumor were associated with ductal histological type (p=0,018), PR-negative status (p=0,027) and high Ki67 (p<0,0001), but not correlated (p>0,05) with age, grade, ER, HER2 status or biological subtype. In women with ER-negative tumors (104 patients, 34,1%) COX2-expression did not associate with worse survival (p>0,05). In contrast to this, in patients with ER-positive tumors (201 women, 65,9%) COX2-expression strongly correlated with worse RFS in univariate (HR 2,829, 95% CI 1,366-5,860, p=0,005) and multivariate analyses (HR=2,972, 95% CI 1,190-7,423, p=0,02). The same value of COX2-expression in women with ER-positive tumors was found for CSS (univariate: HR 3,421, 95% CI 1,436-8,149, p=0,005; multivariate: HR 4,260, 95% CI 1,344-13,504, p=0,014), but not for OS (p>0,05). In women who did not receive adjuvant endocrine therapy (145 patients, 46%) COX2 expression did not have any prognostic value for RFS, OS and CSS (p>0,05) but in patients that used adjuvant endocrine therapy (170 women, 54%) COX2-expression strongly associated with worse cancer-specific survival (HR 5,614 95% CI 1,165-27,059, p=0,032), but not with RFS and OS (p>0,05). Conclusions: COX2 expression plays a role in hormonal pathways and sensitivity for endocrine therapy.

Current and future intraoperative imaging strategies to increase radical resection rates in pancreatic cancer surgery

Prognosis of patients with pancreatic cancer is poor. Even the small minority that undergoes resection with curative intent has low 5-year survival rates. This may partly be explained by the high number of irradical resections, which results in local recurrence and impaired overall survival. Currently, ultrasonography is used during surgery for resectability assessment and frozen-section analysis is used for assessment of resection margins in order to decrease the number of irradical resections. The introduction of minimal invasive techniques in pancreatic surgery has deprived surgeons from direct tactile information. To improve intraoperative assessment of pancreatic tumor extension, enhanced or novel intraoperative imaging technologies accurately visualizing and delineating cancer cells are necessary. Emerging modalities are intraoperative near-infrared fluorescence imaging and freehand nuclear imaging using tumor-specific targeted contrast agents. In this review, we performed a meta-analysis of the literature on laparoscopic ultrasonography and we summarized and discussed current and future intraoperative imaging modalities and their potential for improved tumor demarcation during pancreatic surgery.

Influence of histologic subtype on metastatic pattern in colorectal cancer

395

Background: In colorectal cancer (CRC) mucinous adenocarcinoma (MC) and signet-ring cell carcinoma (SRCC) have been associated with differences in metastatic patterns compared to the more common adenocarcinoma (AC). This study systematically evaluates metastatic patterns of different histological subtypes and analyses metastatic disease based upon primary tumor localization. Methods: A nationwide retrospective review of pathological records of 5,813 patients diagnosed with CRC who underwent an autopsy between 1991 and 2010 was performed. Patients were selected from the Dutch Pathology Registry (PALGA). To validate metastatic patterns in rectal cancer patients, data was compared to the prospective randomized multicentre TME-trial that investigated efficacy of preoperative radiotherapy. Results: In the autopsy study 1,675 patients with CRC had metastatic disease. Metastatic disease was more frequently found in MC and SRCC than in AC (33.9%, 61.2% and 27.5%; P< 0.0001) and more often had metastases at multiple sites (58.6% and 70.7% versus 49.9%; P=0.001). AC more commonly metastasized to the liver compared with MC and SRCC, 73.0% versus 52.2% and 31.7% (P<0.0001). The occurrence of metastases exclusively to the liver was less common in MC and SRCC patients. In SRCC patients, liver metastases were almost always observed in combination with other metastases. MC and SRCC metastasized to the peritoneal surface frequently, 48.2% and 51.2%, compared with 20.1% in AC (P<0.0001). Colon cancer patients presented more frequently with intra-abdominal metastases, than rectal cancer patients. Rectal cancer patients presented more often with extra-abdominal metastases. Results from the TME-trial confirmed findings in rectal cancer patients from the autopsy study. Conclusions: There are profound differences in metastatic patterns between different histological subtypes and the localization of the primary tumor in CRC. Findings from this study should encourage to take histological subtype into account during pre-operative examination for metastases and during follow-up. Results also indicate that these factors should be considered a stratification factor in future research initiatives focusing on advanced disease.

Radiotherapy or surgery of the axilla after a positive sentinel node in breast cancer patients: Final analysis of the EORTC AMAROS trial (10981/22023)

LBA1001

Background: Sentinel node biopsy (SNB) is standard in assessing axillary lymph node status for cN0 breast cancer patients. In case of a positive SNB, if treatment is advised, axillary lymph node dissection (ALND) is the current standard. Although ALND provides excellent regional control, it may give harmful side effects. Axillary radiotherapy (ART) instead of ALND was hypothesized to provide comparable regional control and less side effects. Methods: From 2001 to 2010, patients with cT1E2N0 primary breast cancer were enrolled in the EORTC phase III non-inferiority AMAROS trial. Patients were randomized between ALND and ART in case of a positive SNB. Primary endpoint was 5-year axillary recurrence rate. Secondary endpoints were overall survival (OS), disease-free survival (DFS), quality of life (QOL), shoulder movement and lymphedema at 1 and 5 years. Results: Of the 4,806 patients entered in the trial, 744 in the ALND-arm and 681 in the ART-arm had a positive SNB, 60% with a macrometastasis. The two treatment-arms were comparable regarding age, tumor size, grade, tumor type, and adjuvant systemic treatment. With a median follow up of 6.1 years, the 5-year axillary recurrence rate after a positive SNB was 0.54% (4/744) after ALND versus 1.03% (7/681) after ART. The planned non-inferiority test was underpowered because of the unexpectedly low number of events. The axillary recurrence rate after a negative SNB was 0.8% (25/3131). There were no significant differences between treatment arms regarding OS (5 yr estimates: 93.27% ALND, 92.52% ART, p=0.3386) and DFS (5 yr estimates: 86.90% ALND, 82.65% ART, p=0.1788). Lymphedema was found significantly more often after ALND (1yr: 40% ALND, 22% ART, p<0.0001 and 5yr: 28% ALND, 14% ART, p<0.0001). There was a nonsignificant trend toward more early shoulder movement impairment after ART. These findings were compatible with a trend in two QOL items in the arm symptom scale: swelling (ART better) and movement (ALND better). There were no other differences in QOL. Conclusion: ALND and ART after a positive SNB provide excellent and comparable regional control. ART reduces the risk of short-term and long-term lymphedema compared to ALND. Clinical trial information: NCT00014612.

Radiotherapy or surgery of the axilla after a positive sentinel node in breast cancer patients: Final analysis of the EORTC AMAROS trial (10981/22023)

LBA1001

The full, final text of this abstract will be available at abstract.asco.org at 7:30 AM (EDT) on Monday, June, 3, 2013, and in the Annual Meeting Proceedings online supplement to the June 20, 2013, issue of Journal of Clinical Oncology. Onsite at the Meeting, this abstract will be printed in the Monday edition of ASCO Daily News.

Effect of PK-guided tamoxifen dose escalation on endoxifen serum concentrations in CYP2D6 intermediate and poor metabolizers

595

Background: Breast cancer patients with absent or reduced CYP2D6 activity may benefit less from tamoxifen treatment because of impaired biotransformation to the active metabolite endoxifen. We investigated whether a temporary one-step dose escalation of tamoxifen in CYP2D6 poor (PM) and intermediate metabolizers (IM) could increase endoxifen serum concentration to a similar level observed in CYP2D6 extensive metabolizers (EM) without increasing toxicity. Methods: From a prospective study population of early breast cancer patients using tamoxifen, 12 CYP2D6 poor and 12 intermediate metabolizers were selected and included in a one-step tamoxifen dose escalation study during two months. The escalation dose (120 mg maximum) was calculated by multiplying the individual’s endoxifen level divided by the median endoxifen concentration (33.7 nM) observed in CYP2D6 extensive metabolizers by 20 mg. Toxicity was assessed and all patients returned to the standard dose of 20 mg after two months. Results: Tamoxifen dose escalation in CYP2D6 poor and intermediate metabolizers significantly increased endoxifen concentrations (PMs: from 8.0 nM to 27.3 nM, p<0.001; IMs: from 17.8 nM to 30.3 nM, p=0.002) without increasing side effects. In intermediate but not in poor metabolizers dose escalation increased endoxifen to levels comparable with those observed in extensive metabolizers using tamoxifen 20 mg once daily (33.7 nM). Conclusions: CYP2D6 genotype and endoxifen guided tamoxifen dose escalation increased endoxifen concentrations without increasing short term side effects. Whether such tamoxifen dose escalation is effective and safe in view of long term toxic effects is uncertain and needs to be explored. Clinical trial information: NTR1509.

A combined EpCAM and MCAM circulating tumor cell (CTC) CellSearch enrichment to improve CTC capture rate in stage II/III breast cancer: A Dutch Breast Cancer Trialists' Group (BOOG) side study

e22106

Background: Using the CellSearch System (Veridex, USA), ≥1 CTC/7.5 mL of peripheral blood is found in ~20% of primary breast cancer (BC) patients. However, epithelial cell adhesion molecule (EpCAM)-negative CTCs may be missed. We previously showed that a subset of BC cell lines lacks EpCAM, but does express melanoma cell adhesion molecule (MCAM) and that MCAM-positive CTCs (M-CTCs) do occur in metastatic breast cancer patients. In a side-study of the NEOZOTAC trial, a randomized study comparing neoadjuvant chemotherapy (NAC) with or without zoledronic acid in stage II/III BC, we investigated whether combined enrichment with EpCAM and MCAM increases the CTC detection rate. Besides, we hypothesized that CTC counts would correlate with pathological complete response (pCR) to NAC. Additionally, as exploratory study, circulated endothelial cells (CECs) were measured. Methods: At baseline and after the 1st chemotherapy cycle, blood was drawn from all patients in the NEOZOTAC trial who gave additional informed consent. The CellSearch System was used to count EpCAM-positive CTCs (E-CTCs) and M-CTCs. For the latter, the anti-EpCAM-ferrofluid was replaced by an anti-MCAM-ferrofluid (both Veridex). CECs were measured using flow cytometry. Results: At baseline, blood was received from 73 patients; ≥1 E-CTCs and M-CTCs were detected in 14/73 (19%, median 1) and 8/68 (12%, median 1), respectively. Combining both counts, ≥1 CTCs were detected in 17/68 (25%) of patients (p=0.01). After 1 chemotherapy cycle, E-CTCs, M-CTCs and overall CTCs were detected in 9/47 (19%), 7/45 (16%), and 13/44 (30%; p<0.01) patients. Median CEC count was 43 at baseline and 142 after cycle 1 (p<0.001). No differences in CTC and CEC count were found between the treatment arms. Baseline CTC counts, nor changes in counts, were associated with pCR. Conclusions: Combined enrichment of CTCs with EpCAM and MCAM significantly increased CTC detection rates in stage II/III BC with about 10%. CTC counts were not associated with pCR to NAC. Associations with disease free survival will follow when available.

NEOZOTAC: Efficacy results from a phase III randomized trial with neoadjuvant chemotherapy (TAC) with or without zoledronic acid for patients with HER2-negative large resectable or stage II or III breast cancer (BC)—A Dutch Breast Cancer Trialists’ Group (BOOG) study

1028

Background: The role of bisphosphonates when added to the neoadjuvant treatment of BC in enhancing the efficacy of therapy is still unknown. Methods: NEOZOTAC is a national, multicenter, randomized study comparing the efficacy of TAC (docetaxel, Adriamycin and cyclophosphamide i.v.) CT followed by G-CSF on day 2 with or without ZA 4 mg i.v. ,q 3 weeks in patients (pts) with stage II/III, measurable, HER2-negative BC and absence of prior bisphosphonate usage. The primary endpoint is the pathologic complete response (pCR) rate in the resection specimen and positive lymph nodes. 228 pts are needed to show an improvement of the pCR rates from 17% to 34% in the experimental arm using a 5% significance level based on the two-sided Fisher’s exact test with a power of 80%. Randomization was done by using the Pocock’s minimisation technique stratified by cT, cN and estrogen receptor status. pCR rate was analyzed using the Cochran-Mantel-Haenszel test, adjusting for the stratification factors. Analysis was based on intent-to-treat. An unplanned subgroup analysis of postmenopausal women (PMW; FSH >20 and estradiol <110) and baseline vitamin D levels was performed. Results: From July 2010 to April 2012, 250 patients from 25 participating sites were randomized. Pathologic response data of 228 patients are currently available. pCR rate did not differ between the two study arms (17% vs 16%, p = 0.81). However, a trend in benefit in favor of ZA was observed in PMW (18% vs 11%, OR 1.90, 95% C.I. 0.52 – 6.88). Patients with severe vitamin D insufficiency (<25 nmol/L) seemed to respond worse to CT numerically (6% vs. 18%). At ASCO pCR and clinical response data of all patients will be reported. Conclusions: Previously, we have shown that adding ZA to neoadjuvant CT is safe with good compliance.In this study, treatment with ZA did not result in a pCR benefit in the total study population. However our findings suggest that addition of ZA to neoadjuvant CT might be effective for enhancing response in PMW with BC. Clinical trial information: NCT01099436.

Genetic variation in CYP19A1 and occurrence of adverse events in exemestane treatment with early breast cancer patients in the Dutch TEAM trial

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Background: Aromatase inhibitors (AI) are an important part of treatment of endocrine sensitive breast cancer. Adverse events in patients treated with AI’s often cause treatment discontinuation. The most common adverse events, such as arthralgia, myalgia and hot flushes are probably caused by estrogen deprivation and predict treatment efficacy. It is unclear which patients are at risk to develop these adverse events. The aim of this study was to examine if SNP’s in the CYP19A1 gene can predict the occurrence of adverse events in breast cancer patients treated with adjuvant exemestane. Methods: Patients of whom tissue was available and were selected from the Tamoxifen Exemestane Adjuvant Multinational (TEAM) trial. DNA was isolated from tumor samples and 30 SNPs were identified using a tagging SNP approach, aiming for 80% coverage of CYP19A1. Genotypes were determined with taqman assays. Primary endpoint of the study was the occurrence of adverse events. Secondary endpoints were the occurrence of hot flushes, arthralgia, and myalgia. Results: 807 patients were included in the analyses and genotypes were obtained in 722 cases. One SNP, rs8031311, was associated with a higher incidence of adverse events with an odds ratio of 2.8. Four SNP's were associated with an increased incidence of hot flushes: rs934635, rs4775928, rs16964189, rs6493496 with odds ratio’s of 2.9, 1.8, 1.8 and 2.6 respectively. No association was found between variation in CYP19A1 and the occurrence of arthralgia or myalgia. Conclusions: Germline variation in the CYP19A1 gene is related to the occurrence of adverse events, specifically hot flushes, in early breast cancer patients treated with exemestane. These findings may contribute to the individualization of hormonal therapy in breast cancer. [Table: see text]

Primary metastatic breast cancer in elderly: An international comparison

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Background: In primary metastatic breast cancer in elderly, both advanced age and advanced disease limit life expectancy. It remains a challenge to balancing the benefit from therapy and risk of adverse events impeding quality of life or survival. Our aim was to compare management and outcome of primary metastatic breast cancer in elderly treated in two health care settings. Methods: The first cohort comprised a hospital based series in the United States (US, n=73 women diagnosed between 2003 and 2012); the second comprised a population based series in The Netherlands (NL, n=125 women diagnosed between 2008 and 2012). All were ≥65 years at the time of diagnosis. Country was used as an instrumental variable, as a proxy for randomization to either care setting. Multivariable survival analyses were adjusted for age, comorbidity, T stage, nodal stage and hormone receptor status. Results: Characteristics of US and NL patients were similar, except for age (median 72; 79 years, p>0.001). US patients more often received breast surgery and chemotherapy in particular, less often endocrine therapy as monotherapy (Table), and received more lines of treatment (median 4; 2, p<0.001). Adverse events rarely were a reason for a next line of therapy (6% in each cohort). Three-year survival tended to be higher in US patients (HR for US patients was 0.71 (95% CI 0.48-1.05), p=0.089). Multivariable analyses revealed no survival differences (HR for US patients was 0.86 (95% CI 0.53-1.38), p=0.523). Results were similar after stratifying by age at diagnosis (<70; ≥70 years). Conclusions: Treatment of elderly with primary metastatic breast cancer varied considerably between the NL and the US cohort. However, no differences in overall survival were observed. These results warrant further studies to evaluate the extent of treatment in this population. [Table: see text]

CYP2D6 genotype related to tamoxifen efficacy: An analysis with exclusion of potential false CYP2D6 genotype assignment caused by loss of heterozygosity in tumor tissue

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Background: The clinical importance of CYP2D6 genotype as predictor of tamoxifen efficacy is still unclear. Recent genotyping studies on CYP2D6 using DNA derived from tumor blocks have been criticized because loss of heterozygosity (LOH) in tumors may lead to false genotype assignment. Methods: Postmenopausal early breast cancer patients who were randomized to receive tamoxifen, followed by exemestane in the Tamoxifen Exemestane Adjuvant Multinational trial (TEAM) were genotyped for 5 CYP2D6 variant alleles. CYP2D6 genotypes and phenotypes were related to disease free survival during tamoxifen use (DFS-t) in 731 patients. By analyzing three microsatellites flanking the CYP2D6 gene, patients whose genotyping results were potentially affected by LOH were excluded. Results: Analysis of the CYP2D6 alleles and the microsatellite markers demonstrated heterozygosity for at least one of the CYP2D6 alleles or microsatellite markers in 97.7% of patients with a specified CYP2D6 phenotype. The 14 patients (2.3%) with a homozygous CYP2D6 genotype in which no heterozygosity could be demonstrated for the microsatellite markers were excluded from the analysis. No association was found between the CYP2D6 genotype or predicted phenotype and DFS-t. Conclusions: In postmenopausal early breast cancer patients treated with adjuvant tamoxifen followed by exemestane neither CYP2D6 genotype nor phenotype was associated with DFS-t. This is in accordance with two recent studies in the BIG1-98 and ATAC trials. Our study is the first CYP2D6 association study using DNA from paraffin embedded tumor tissue in which potentially false interpretation of genotyping results because of LOH was excluded.

Validation of IHC4 algorithms for prediction of risk of recurrence in early breast cancer using both conventional and quantitative IHC approaches

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Background: Hormone receptors, HER2 and Ki67 are residual risk markers in early breast cancer. Combining these markers into a unified algorithm (IHC4) provides information on residual recurrence risk of patients treated with hormone therapies. This study aimed to independently investigate the validity of the IHC4 algorithm for residual risk prediction using both conventional (DAB)-IHC and quantitative immunofluorescence (QIF-AQUA). Methods: The TEAM pathology study recruited >4500 samples from patients treated in the TEAM trial. TMAs were stained for ER, PgR, HER2 and Ki67 using QIF-AQUA technology or DAB-based immunohistochemistry (DAB-IHC). Central HER2 FISH was performed. Quantitative image analysis was used to generate expression scores that were normalized to produce “IHC4 algorithm” as well as novel algorithm scores.  Algorithm scores were compared with disease recurrence in univariate and multivariate Cox Proportional Hazards models. Results: Both DAB-IHC and QIF-AQUA IHC4 continuous models were significant (P<0.0001) for prediction of disease recurrence with a continuous Hazard Ratio (HR) of 1.011 (1.010 – 1.013) for QIF-AQUA IHC4 versus 1.008 (1.007 – 1.010) for the DAB-IHC IHC4 model using the published IHC4 algorithm (Cuzick et al 2011).  Binning continuous model scores (4 bins) by Kaplan-Meier survival analysis was used to graphically illustrate these effects.  De novo models for both DAB-IHC and QIF-AQUA were also significantly (P<0.0001) predictive of residual risk in early breast cancer. Additionally, all 4 models were independent predictors of recurrence (P<0.0001) with other recognized clinical prognostic factors in multivariate analysis.  Although results from DAB and QIF-AQUA were modestly correlated, the QIF-AQUA model showed enhanced prediction of recurrence in both Cox Proportional Hazards Modeling and C-index calculations. Conclusions: Either conventional DAB or QIF-AQUA methods of IHC provided evidence supporting the clinical utility of IHC4 algorithms in the context of the TEAM study.  With careful standardization, either of these IHC4 assays should be considered for prediction of residual risk in early breast cancer.

Common polymorphisms in the estrogen receptor-1 may determine risk of hot flashes in early breast cancer patients using tamoxifen

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Background: In breast cancer patients the occurrence of hot flashes as common side effect of tamoxifen therapy may be associated with effective estrogen receptor antagonism dependent on genetic variations of metabolic enzymes and the estrogen receptor. Methods: 742 early breast cancer patients who were randomized to receive tamoxifen, followed by exemestane after 2.5 to 3 years within the Tamoxifen Exemestane Adjuvant Multinational (TEAM) Trial were genotyped for 30 germ line genetic variants of 11 enzymes that are involved in the tamoxifen metabolism and the estrogen receptor 1 (ESR1). These genetic variants were related to the occurrence of hot flashes during the first year of tamoxifen use (primary aim) and during the complete tamoxifen treatment period (secondary aim). A multivariable logistic regression was used to adjust for age and adjuvant chemotherapy. Results: No genetic variant was associated with the occurrence of hot flashes during the first year. Higher age was related to a lower incidence of hot flashes in the first year (adjusted odds ratio 0.94, 95% CI 0.92-0.96; p<0.001). The ESR1 PvuII XbaI CG haplotype (CG/CG vs CG/other + other/other: adjusted odds ratio 0.44, 95% CI 0.21-0.92; p=0.03), ESR1 PvuII XbaI TA haplotype (TA/TA + TA/other vs other/other: adjusted odds ratio 1.86, 95% CI 1.09-3.14; p=0.02) and age (adjusted odds ratio 0.94, 95% CI 0.92-0.97; p<0.001) were associated with the occurrence of hot flashes during the total tamoxifen treatment period. No association was found between the CYP2D6 predicted phenotype and hot flashes. Conclusions: Common polymorphisms in the estrogen receptor-1 might help to predict the occurrence of hot flashes in breast cancer patients treated with adjuvant tamoxifen. If replicated, this may provide clinicians with a tool to offer more personalized hormonal therapy.

Mammostrat as an immunohistochemical multigene assay for prediction of early relapse risk in the TEAM pathology study

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Background: Some postmenopausal patients with hormone sensitive early breast cancer remain at high risk of relapse despite endocrine therapy, and might benefit additionally from adjuvant chemotherapy. The challenge is to prospectively identify such patients. The Mammostrat test uses five immunohistochemical markers to stratify patients regarding recurrence risk, and may inform treatment decisions. We tested the efficacy of this panel in the TEAM trial. Methods: Pathology blocks from 4598 TEAM patients were collected and TMAs constructed. The cohort was 47% node positive and 36% were also treated with adjuvant chemotherapy. Triplicate 0.6mm2 TMA cores were stained and positivity for p53, HTF9C, CEACAM5, NDRG1, SLC7A5 assessed. Cases were assigned a Mammostrat risk score, and distant relapse free (DRFS) and disease free survival (DFS) analysed. Results: In multivariate regression analyses, corrected for conventional clinicopathological markers, Mammostrat provided significant additional information on DRFS after endocrine therapy in ER positive node negative patients (N=1226) not receiving chemotherapy (p=0.004). Further analyses in all patients not exposed to chemotherapy, irrespective of nodal status (N=2559) and in the entire cohort (N=3837) showed Mammostrat scores provide additional information on DRFS in these groups (p=0.001 and p<0.0001 respectively; multivariate analyses). No differences were seen between the two endocrine treatment regimens. Conclusions: The Mammostrat score predicts DRFS for both exemestane and tamoxifen-exemestane treated patients irrespective of nodal status and chemotherapy. The ability of this test to provide additional outcome data following treatment provides further evidence for its’ utility in risk stratification of ER positive postmenopausal breast cancer patients.

Results of a comparison between European countries for esophagectomy and gastrectomy: Initiative for a European upper GI audit (EURECCA Upper GI)

98

Background: In Europe, several countries have implemented national audit programs to reduce variation in outcomes and improve care for esophageal and gastric cancer. These audits provide insight in national variations, but currently no international comparisons can be made. Purposes of the current study were to compare patterns of care and outcomes in several European countries, and to evaluate the effect of hospital volume on outcomes for esophagectomy and gastrectomy.

Methods: Data were obtained from national cancer registries or audits in the Netherlands, Sweden, Denmark, and the United Kingdom. Differences in postoperative 30-day mortality and 2-year survival were adjusted for available case-mix variables and separately analyzed for esophagectomy and gastrectomy, using generalized estimated equations and Cox regression. In the current study, high-volume hospitals were defined as hospitals with an annual volume of > 20.

Results: From 2004-2009, 10,854 esophagectomies and 9,010 gastrectomies were performed in the participating countries. Availability of case-mix variables varied between countries, and a limited number of variables could be used in the international comparison. On univariate analysis, 30-day mortality and 2 year survival differed significantly between participating countries, but on multivariate analysis, no significant differences were found. The percentage of resections performed in high-volume hospitals varied considerably between countries (esophagectomy: 20% to 94%, gastrectomy: 0% to 59%). Increasing annual hospital volume was associated with lower 30-day mortality after esophagectomy (P < 0.001) and gastrectomy (P = 0.025), and with improved 2-year survival after esophagectomy (P = 0.004), but not after gastrectomy.

Conclusions: This study provides an initial step towards a European Upper GI Cancer Audit. However, with the available data only limited case-mix adjustments could be made. Future steps would include synchronization of registered variables and the use of uniform variable definitions. Increasing annual hospital volume is associated with improved short-term outcomes of upper GI cancer surgery.

Cost-utility analysis of preoperative radiotherapy in patients with rectal cancer undergoing total mesorectal excision: a study of the Dutch Colorectal Cancer Group

PURPOSE

To compare the societal costs and the (quality-adjusted) life expectancy of patients with rectal cancer undergoing total mesorectal excision (TME) with or without short-term preoperative radiotherapy (5 x 5 Gy).

PATIENTS AND METHODS

We used a Markov model to project the clinical and economic outcomes of preoperative radiotherapy. Data on local recurrence rates, quality of life, and costs were obtained from the patients of a multicenter randomized clinical trial. In this trial, 1,861 patients with resectable rectal cancer from 108 hospitals were randomly assigned for TME surgery with or without preoperative radiotherapy. Outcome measures of the model were life expectancy, quality-adjusted life expectancy, lifetime costs per patient, and the incremental cost-effectiveness ratio.

RESULTS

The base case model estimates that the loss of quality of life due to preoperative radiotherapy is outweighed by the gain in life expectancy. Life expectancy increases by 0.67 years; quality-adjusted life expectancy, by 0.39 years; and costs, by $9,800 per patient. The corresponding cost-effectiveness ratio is $25,100 per quality-adjusted life year. Sensitivity analyses indicate that the cost-effectiveness ratio remains acceptable under a wide range of assumptions.

CONCLUSION

Assuming that the reduced local recurrence rate does lead to a survival advantage, the cost-utility analysis estimates that the improved survival outweighs the impaired quality of life and the increased costs. We conclude that short-term preoperative radiotherapy in patients with rectal cancer undergoing TME is both effective and cost-effective.

A tumor-specific kinase activity regulates the viral death protein Apoptin

Apoptin, a chicken anemia virus-encoded protein, is thought to be activated by a general tumor-specific pathway, because it induces apoptosis in a large number of human tumor or transformed cells but not in their normal, healthy counterparts. Here, we show that Apoptin is phosphorylated robustly both in vitro and in vivo in tumor cells but negligibly in normal cells, and we map the site to threonine 108. A gain-of-function point mutation (T108E) conferred upon Apoptin the ability to accumulate in the nucleus and kill normal cells, implying that phosphorylation is a key regulator of the tumor-specific properties of Apoptin. An activity that could phosphorylate Apoptin on threonine 108 was found specifically in tumor and transformed cells from a variety of tissue origins, suggesting that activation of this kinase is generally associated with the cancerous or pre-cancerous state. Moreover, analyses of human tissue samples confirm that Apoptin kinase activity is detectable in primary malignancies but not in tissue derived from healthy individuals. Taken together, our results support a model whereby the dysregulation of the cellular pathway leading to the phosphorylation of Apoptin contributes to human tumorigenesis.

Down-regulation of HLA-A expression correlates with a better prognosis in colorectal cancer patients

To evaluate the prognostic impact of human leukocyte antigen class I (HLA-I) expression on immune surveillance in colorectal cancer, we studied 88 curatively resected tumors for HLA-A and HLA-B/C expression and correlated these data to clinical and histopathological parameters. HLA-A was normal (all tumor cells had HLA expression) in 32%, reduced (HLA-negative and -positive tumor cells coexisted) in 56%, or absent (no tumor cells expressed HLA) in 12% of evaluable cases. HLA-B/C was normal in 47%, reduced in 47%, and absent in 7% of the cases. Considering both markers, total HLA-I expression was normal in 27%, reduced in 63%, absent in 7%, and could not be evaluated in 3% of the cases due to absent HLA-A expression in tumor and normal cells. Down-regulation of HLA-A expression significantly correlated with a lower tumor stage (p = 0.005), mucinous tumors (p = 0.05), a lower incidence of recurrences (p = 0.03), and a longer disease-free survival (p = 0.02). Down-regulation of HLA-B/C expression correlated with a lower tumor stage (p < 0.001) and a longer disease-free survival (p = 0.04). In multivariate analysis, HLA-A down-regulation was the only prognostic factor correlated with a longer disease-free survival (p = 0.02). Six tumors were negative for HLA-A and -B/C and did not recur during follow-up. Therefore, we analyzed microsatellite instability (MSI) in these cases. Three of these six tumors indeed showed down-regulation of MLH-1, MSH-2, or MSH-6, indicating a MSI-high phenotype. Beta-2-microglobulin protein expression was lost in five of six of the HLA-I-negative cases, but frame shift mutations in three repetitive sequences in beta2-microglobulin were absent. In contrast, loss of MLH-1, MSH-2, and MSH-6-protein expression was only observed in two of nine matched controls with reduced or normal HLA-A and -B/C expression. Our data showed that HLA-I was down-regulated in 72% of colorectal cancers and provided independent prognostic information for a longer disease-free survival. The better prognosis may be caused by elimination of HLA-negative cells by natural killer cells or by an attenuated tumor aggressiveness, as is seen in tumors with a MSI-high phenotype.