Steven Teerenstra

KRAS mutation analysis: a comparison between primary tumours and matched liver metastases in 305 colorectal cancer patients

Background:KRAS mutation is a negative predictive factor for treatment with anti-epidermal growth factor receptor antibody in metastatic colorectal cancer (CRC). KRAS mutation analysis is usually performed on primary tumour tissue because metastatic tissue is often not available. However, controversial data are available on the concordance of test results between primary tumours and corresponding metastases. We assessed the concordance of KRAS mutation status in a study of 305 primary colorectal tumours and their corresponding liver metastases.Methods:Patients with histologically confirmed CRC who underwent surgical resection of the primary tumour and biopsy or surgical resection of the corresponding liver metastasis were included. KRAS mutation analysis was performed for codons 12 and 13.Results:KRAS mutation was detected in 108 out of 305 primary tumours (35.4%). In 11 cases (3.6%), we found a discordance between primary tumour and metastasis: 5 primary tumours had a KRAS mutation with a wild-type metastasis, 1 primary tumour was wild type with a KRAS mutation in the metastasis, and in 5 cases the primary tumour and the metastasis had a different KRAS mutation.Conclusion:We observed a high concordance of KRAS mutation status of 96.4% (95% CI 93.6–98.2%) between primary colorectal tumours and their corresponding liver metastases. In only six patients (2.0%; 95% CI 0.7–4.2%), the discordance was clinically relevant. In this largest and most homogenous study to date, we conclude that both primary tumours and liver metastases can be used for KRAS mutation analysis.

Markers for EGFR pathway activation as predictor of outcome in metastatic colorectal cancer patients treated with or without cetuximab

BACKGROUND Anti-EGFR monoclonal antibodies in metastatic colorectal cancer (mCRC) treatment are only effective in patients with KRAS wild type tumours. Here we assess the predictive value of other potential relevant markers involved in the epidermal growth factor receptor (EGFR) signalling pathways for response to cetuximab-based treatment. MATERIALS AND METHODS Formalin-fixed paraffin-embedded colorectal cancer tissue of the primary tumour was obtained from 559 mCRC patients treated with chemotherapy and bevacizumab with or without cetuximab (phase III CAIRO2 study). DNA was isolated for mutation analysis of BRAF (V600E), KRAS (codon 12 and 13) and PIK3CA (exon 9 and 20). Tissue microarrays (TMAs) were constructed for the assessment of EGFR and HER2 gene copy number (GCN), and EGFR and PTEN protein expression. The results of these markers, individually or in combination, were correlated with progression-free survival (PFS) and overall survival (OS) in the subgroup of patients with a KRAS wild type tumour treated in the cetuximab-arm. KRAS wild type patients treated without cetuximab were used as a control group. RESULTS A total of 208 tumours (39.4%) contained a KRAS mutation, 8.7% a BRAF mutation and 9.9% a PIK3CA mutation. Loss of PTEN expression and the presence EGFR protein expression were observed in 42.0% and 61.7% of the samples, respectively. An increased EGFR GCN was observed in 15.3% of the samples, and 11.5% of the evaluable samples contained an increased HER2 GCN. In KRAS wild type patients treated with cetuximab a BRAF mutation was significantly and independently associated with PFS and OS. In patients treated without cetuximab the PFS and OS were also associated with the BRAF genotype. No prognostic or predictive value was observed for any of the other markers when tested individually or in combination. CONCLUSIONS BRAF genotype is correlated with PFS and OS in KRAS wild type mCRC patients, which is independent of cetuximab treatment. PIK3CA mutation, loss of PTEN expression, EGFR GCN and HER2 GCN have no predictive value for response to treatment with cetuximab, neither individually nor in combination with other markers.

Predicting lymph node metastasis in pT1 colorectal cancer: a systematic review of risk factors providing rationale for therapy decisions

BACKGROUND AND STUDY AIM Population screening for colorectal cancer (CRC) is expected to increase the number of pT1 CRCs. Local excision is an attractive treatment option, but is only oncologically safe in the absence of lymph node metastasis (LNM). A systematic review of the predictive value of pathological risk factors for LNM in pT1 CRC was conducted to provide data for an evidence-based decision regarding follow-up or radical surgery after local excision. METHODS PubMed was searched for reports on predictors of LNM in pT1 CRC. Published papers written in English and containing at least 50 patients were included. Meta-analyses were performed using Review Manager 5.1. RESULTS A total of 17 studies were included involving a total of 3621 patients with available nodal status. The strongest independent predictors of LNM were lymphatic invasion (relative risk [RR] 5.2, 95 % confidence interval [CI] 4.0 - 6.8), submucosal invasion ≥ 1 mm (RR 5.2, 95 %CI 1.8 - 15.4), budding (RR 5.1, 95 %CI 3.6 - 7.3), and poor histological differentiation (RR 4.8, 95 %CI 3.3 - 6.9). Limitations of the study were: results could not be stratified according to location in the colon or rectum; very early tumors removed by polypectomy without surgical resection were not included in the meta-analysis; and included studies were primarily from Asian countries and results therefore need to be verified in Western populations. CONCLUSION The absence of lymphatic invasion, budding, submucosal invasion ≥ 1 mm, and poor histological differentiation were each associated with low risk of LNM. Risk stratification models integrating these factors need to be investigated further.

Stepped wedge designs could reduce the required sample size in cluster randomized trials

OBJECTIVE The stepped wedge design is increasingly being used in cluster randomized trials (CRTs). However, there is not much information available about the design and analysis strategies for these kinds of trials. Approaches to sample size and power calculations have been provided, but a simple sample size formula is lacking. Therefore, our aim is to provide a sample size formula for cluster randomized stepped wedge designs. STUDY DESIGN AND SETTING We derived a design effect (sample size correction factor) that can be used to estimate the required sample size for stepped wedge designs. Furthermore, we compared the required sample size for the stepped wedge design with a parallel group and analysis of covariance (ANCOVA) design. RESULTS Our formula corrects for clustering as well as for the design. Apart from the cluster size and intracluster correlation, the design effect depends on choices of the number of steps, the number of baseline measurements, and the number of measurements between steps. The stepped wedge design requires a substantial smaller sample size than a parallel group and ANCOVA design. CONCLUSION For CRTs, the stepped wedge design is far more efficient than the parallel group and ANCOVA design in terms of sample size.

Outcomes of colorectal cancer patients with peritoneal carcinomatosis treated with chemotherapy with and without targeted therapy

BACKGROUND Although systemic therapies have shown to result in survival benefit in patients with metastatic colorectal cancer (mCRC), outcomes in patients with peritoneal carcinomatosis (PC) are poor. No data are available on outcomes of current chemotherapy schedules plus targeted agents in mCRC patients with PC. METHODS Previously untreated mCRC patients treated with chemotherapy in the CAIRO study and with chemotherapy and targeted therapy in the CAIRO2 study were included and retrospectively analysed according to presence or absence of PC at randomisation. Patient demographics, primary tumour characteristics, progression-free survival (PFS), overall survival (OS), and occurrence of toxicity were evaluated. RESULTS Thirty-four patients with PC were identified in the CAIRO study and 47 patients in the CAIRO2 study. Median OS was decreased for patients with PC compared with patients without PC (CAIRO: 10.4 versus 17.3 months, respectively (p ≤ 0.001); CAIRO2: 15.2 versus 20.7 months, respectively (p < 0.001)). Median number of treatment cycles did not differ between patients with or without PC in both studies. Occurrence of major toxicity was more frequent in patients with PC treated with sequential chemotherapy in the CAIRO study as compared to patients without PC. This was not reflected in reasons to discontinue treatment. In the CAIRO2 study, no differences in major toxicity were observed. CONCLUSION Our data demonstrate decreased efficacy of current standard chemotherapy with and without targeted agents in mCRC patients with PC. This suggests that the poor outcome cannot be explained by undertreatment or increased susceptibility to toxicity, but rather by relative resistance to treatment.

Clinicopathological features and outcome in advanced colorectal cancer patients with synchronous vs metachronous metastases

Background:Synchronous metastases of colorectal cancer (CRC) are considered to be of worse prognostic value compared with metachronous metastases, but only few and conflicting data have been reported on this issue.Methods:We retrospectively investigated patient demographics, primary tumour characteristics and overall survival (OS) in 550 advanced CRC patients with metachronous vs synchronous metastases, who participated in the phase III CAIRO study. For this purpose only patients with a prior resection of the primary tumour were considered.Results:The clinical and pathological characteristics associated with poor prognosis that we observed more often in patients with synchronous metastases (n=280) concerned an abnormal serum lactate dehydrogenase (LDH) concentration (P=0.01), a worse WHO performance status (P=0.02), primary tumour localisation in the colon (P=0.002) and a higher T stage (P=0.0006). No significant difference in median OS was observed between patients with synchronous metastases and metachronous metastases (17.6 vs 18.5 months, respectively, P=0.24).Conclusion:Despite unfavourable clinicopathological features in patients with synchronous metastases with a resected primary tumour compared to patients with metachronous metastases, no difference in the median OS was observed. Possible explanations include a (partial) chemoresistance in patients with metachronous disease because of previous adjuvant treatment, whereas differences between the two groups in screening procedures resulting in a lead time bias to diagnosis or in prognostic molecular markers remain speculative.

Mucinous adenocarcinomas: poor prognosis in metastatic colorectal cancer.

PURPOSE Mucinous histology of metastatic colorectal cancer (CRC) has been associated with poor prognosis, however this has never been assessed in large well-defined study populations treated with the current used systemic agents. We investigated the prognostic value of mucinous histology in two large phase III studies in metastatic CRC. PATIENTS AND METHODS The study population included 1010 metastatic CRC patients who were treated with chemotherapy and targeted therapies in two phase III studies. Patients were classified according to the histology of the primary tumour in mucinous adenocarcinomas (MC) and non-mucinous adenocarcinomas (AC). RESULTS Patients with MC (n=99) were older, had more often a normal serum lactate dehydrogenase (LDH), extrahepatic localisation of metastases, larger primary tumour diameter and a higher T classification compared to patients with AC (n=911). A deficient mismatch repair system and BRAF mutations were observed in 17% and 22% of patients with MC, compared to 3% and 7% in patients with AC, respectively. Clinical outcome was investigated in both studies separately, showing a worse overall survival (OS), progression free survival and overall response rate in patients with MC compared to patients with AC. Patients with MC received less cycles of treatment compared to AC, but did not suffer from a higher incidence of grade 3/4 toxicity. In multivariate analysis, mucinous histology was as an independent negative prognostic factor for OS, resulting in a combined hazard ratio of 1.78 (95%confidence interval (CI) 1.35-2.35). CONCLUSIONS Patients with metastatic mucinous CRC have distinct clinicopathological features and poor response to chemotherapy and targeted agents. The strong negative prognostic value of MC warrants the use of this pathological feature as a stratification factor for clinical trials in metastatic CRC.

Systematic review of the effect of external beam radiation therapy to the breast on axillary recurrence after negative sentinel lymph node biopsy

Axillary recurrence after negative sentinel lymph node biopsy (SLNB) in patients with invasive breast carcinoma remains a concern. Previous investigations to identify prognostic factors for axillary recurrence identified that a disproportionate number of patients with an axillary recurrence after negative SLNB were not treated with external beam radiation therapy (EBRT) of the breast as part of initial treatment. This finding prompted a systematic review to test the hypothesis that EBRT to the breast reduces the risk of axillary recurrence after negative SLNB.

Influence of body mass index on outcome in advanced colorectal cancer patients receiving chemotherapy with or without targeted therapy

PURPOSE Obesity is associated with an increased risk of development and recurrence of colorectal cancer. However, the role of obesity in advanced colorectal cancer (ACC) patients is unknown. We investigated the effect of body mass index (BMI) on overall survival (OS) in ACC patients receiving systemic treatment in two large phase III studies (CAIRO and CAIRO2). PATIENTS AND METHODS Treatment data were obtained and analysed from 796 ACC patients who were treated with chemotherapy in the CAIRO study, and from 730 ACC patients who were treated with chemotherapy plus targeted therapy in the CAIRO2 study. Baseline height and weight were used to assign patients to one of the following BMI categories: A (<18.5 kg/m(2)), B (18.5-24.9 kg/m(2)), C (25.0-29.9 kg/m(2)) and D (≥30.0 kg/m(2)). RESULTS In 796 patients of the CAIRO study a high BMI was associated with better median OS (8.0, 14.9, 18.4 and 19.5 months for BMI categories A, B, C, and D, respectively; P=0.001), and was an independent prognostic factor for OS in a multivariate analysis. BMI was not associated with OS in 730 patients who participated in the CAIRO2 study, although a trend was observed. CONCLUSIONS These results show that BMI is an independent prognostic factor for survival in patients receiving chemotherapy, but not in patients receiving chemotherapy and targeted therapy. The possible decreased efficacy of bevacizumab in obese patients may explain this discrepant result. The role of BMI in patients receiving targeted therapy should be further tested.

Beyond KRAS mutation status: influence of KRAS copy number status and microRNAs on clinical outcome to cetuximab in metastatic colorectal cancer patients

BackgroundKRAS mutation is a negative predictive factor for treatment with anti-epidermal growth factor receptor (EGFR) antibodies in metastatic colorectal cancer (mCRC). Novel predictive markers are required to further improve the selection of patients for this treatment. We assessed the influence of modification of KRAS by gene copy number aberration (CNA) and microRNAs (miRNAs) in correlation to clinical outcome in mCRC patients treated with cetuximab in combination with chemotherapy and bevacizumab.MethodsFormalin-fixed paraffin-embedded primary tumour tissue was used from 34 mCRC patients in a phase III trial, who were selected based upon their good (n = 17) or poor (n = 17) progression-free survival (PFS) upon treatment with cetuximab in combination with capecitabine, oxaliplatin, and bevacizumab. Gene copy number at the KRAS locus was assessed using high resolution genome-wide array CGH and the expression levels of 17 miRNAs targeting KRAS were determined by real-time PCR.ResultsCopy number loss of the KRAS locus was observed in the tumour of 5 patients who were all good responders including patients with a KRAS mutation. Copy number gains in two wild-type KRAS tumours were associated with a poor PFS. In KRAS mutated tumours increased miR-200b and decreased miR-143 expression were associated with a good PFS. In wild-type KRAS patients, miRNA expression did not correlate with PFS in a multivariate model.ConclusionsOur results indicate that the assessment of KRAS CNA and miRNAs targeting KRAS might further optimize the selection of mCRC eligible for anti-EGFR therapy.