Alaa Abduljabbar

Prognostic significance of alterations in KRAS isoforms KRAS-4A/4B and KRAS mutations in colorectal carcinoma

Somatic KRAS mutation is an early well‐known event in colorectal carcinogenesis but a complete understanding of RAS function and dysfunction in colorectal cancer is still to come. Our aim was to study the incidence of KRAS mutation; KRAS splice variants: KRAS4A and KRAS4B; and their relationships with various clinico‐pathological characteristics in colorectal cancer (CRC).In this study, 285 CRC cases were analysed for KRAS mutation by direct DNA sequencing followed by immunohistochemical analysis after validation with real‐time PCR assay, to study the protein expression of KRAS4A and ‐4B isoforms. KRAS gene mutations were seen in 80/285 CRCs (28.1%) and of the mutated cases, the majority of the mutations were seen in codon 12 (81.2%) as opposed to codon 13 (18.8%). CRCs with KRAS mutations were associated with a poor overall survival (p = 0.0009). Furthermore, KRAS mutations at codon 12 were associated with a poor overall survival of 64.4% at 5 years compared with a 5‐year overall survival of 75.8% and 78.2% with codon 13 mutation and absence of KRAS mutations, respectively (p = 0.0025). KRAS4A protein expression was predominantly seen in the cytoplasm, while KRAS4B protein was nuclear. KRAS4A overexpression was significantly associated with left colon, histology subtype of adenocarcinoma, p27kip1, and cleaved caspase3 expression. Interestingly, KRAS4A overexpression was associated with a better overall survival (p = 0.0053). On the other hand, KRAS4B overexpression (33.2%) was significantly associated with larger tumour size (p = 0.0234) and inversely correlated with p27kip1 protein (p = 0.0159). Both KRAS mutation and KRAS4A were independent prognostic markers in a multivariate analysis with age, gender, stage, differentiation, and MSI status. Our results highlight the differential role of KRAS isoforms in CRC, their utility as a prognostic biomarker, and underline the importance of KRAS alterations as a potential therapeutic target for CRC. Copyright

Laparoscopic ovarian transposition before pelvic radiation in rectal cancer patient: safety and feasibility

BackgroundInfertility due to pelvic radiation for advanced rectal cancer treatment is a major concern particularly in young patients. Pre-radiation laparoscopic ovarian transposition may offer preservation of ovarian function during the treatment however its use is limited.AimThe study investigates the safety, feasibility and effectiveness of pre-radiation laparoscopic ovarian transposition and its effect on ovarian function in the treatment o locally advanced rectal cancer.MethodsCharts review of all young female patients diagnosed with locally advanced rectal cancer, underwent laparoscopic ovarian transposition, then received preoperative radiotherapy at king Faisal Specialist Hospital and Research Centre between 2003–2007.ResultsDuring the period studied three single patients age between 21–27 years underwent pre-radiation laparoscopic ovarian transposition for advanced rectal cancer. All required pretreatment laparoscopic diversion stoma due to rectal stricture secondary to tumor that was performed at the same time. One patient died of metastatic disease during treatment. The ovarian hormonal levels (FSH and LH) were normal in two patients. One has had normal menstrual period and other had amenorrhoea after 4 months follow-up however her ovarian hormonal level were within normal limits.ConclusionsLaparoscopic ovarian transposition before pelvic radiation in advanced rectal cancer treatment is an effective and feasible way of preservation of ovarian function in young patients at risk of radiotherapy induced ovarian failure. However, this procedure is still under used and it is advisable to discuss and propose it to suitable patients.

Colorectal cancer in Saudi Arabia: incidence, survival, demographics and implications for national policies.

BACKGROUND AND OBJECTIVES The national data on colorectal cancer in Saudi Arabia has not been analyzed. The objective of this study is to describe the demographics, incidence and survival rates for colorectal cancer in Saudi Arabia for the period 1994–2010. DESIGN Retrospective analysis of the Saudi Cancer Registry data for the period 1994–2010. SETTING Data from the Saudi Cancer Registry was analyzed by stage at presentation (local, regional, distal, unknown) and survival rates were calculated using the Kaplan-Meier method. PATIENTS From 9889 colorectal cancer cases, a sample of 549 (5.6%) patients was selected and their living status ascertained to assess survival. RESULTS Colorectal cancer has been the most common cancer among men and the third commonest among women since 2002 in Saudi Arabia. There has been a slight predominance among men with an average ratio of 116:100 over the years (range: 99:100–132:100). The overall age-standardized rate (ASR) approached a plateau of 9.6/100 000 in 2010. The incidence of the disease has been highest in the capital, Riyadh, where it reached 14.5/100 000 in 2010. Median age at presentation has been stable at around 60 years (95% confidence Interval (CI): 57–61 years) for men and 55 years (95% CI: 53–58 years) for women. Distant metastasis was diagnosed in 28.4% of patients at the time of presentation and rectal cancer represented 41% of all colorectal cancers diagnosed in 2010. The overall 5-year survival was 44.6% for the period 1994–2004. The ASR for all age groups below 45 years of age was lower than that for the United States. LIMITATIONS The study was retrospective with a possibility of bias from inaccurate staging of patients, and inaccurate survival information and patient demographics due to the underdeveloped census system prior to 2001. Survival data for the period 2005–2010 are lacking. CONCLUSION Colorectal cancer presents at a younger age in Saudis, especially in women. This has a major implication for decisions about the threshold age for screening. The ASR has increased, but is still much lower than in developed countries. The lower overall 5-year survival compared with developed countries is due to lack of screening, a higher proportion of advanced stage cancer at presentation, lack of specialized care outside the major cities and a higher proportion of rectal cancer cases.

MED12 is recurrently mutated in Middle Eastern colorectal cancer

Objective Colorectal cancer (CRC) is a common cancer and a leading cause of cancer deaths. Previous studies have identified a number of key steps in the evolution of CRC but our knowledge of driver mutations in CRC remains incomplete. Recognising the potential of studying different human populations to reveal novel insights in disease pathogenesis, we conducted genomic analysis of CRC in Saudi patients. Design In the discovery phase of the study, we conducted whole genome sequencing of tumour and corresponding germline DNA in 27 patients with CRC. In addition to known driver mutations, we identified three MED12 somatic mutations. In the replication phase, we employed a next-generation sequencing approach to capture and sequence MED12 and other candidate genes in a larger sample of 400 patients with CRC and confirmed the enrichment for recurrent MED12 mutations. Results In order to gain insight into a plausible biological mechanism for the potential role of MED12 mutations in CRC, we studied CRC cell lines that differ substantially in the expression level of MED12, and found the latter to be correlated inversely with transforming growth factor (TGF)-β signalling and directly with apoptosis in response to chemotherapeutic agents. Importantly, these correlations were replicated when MED12 expression was experimentally manipulated. Conclusions Our data expand the recently described role of MED12 as a tumour suppressor in other cancers to include CRC, and suggest TGF-β signalling as a potential mediator of this effect.

Risk Factors for Abdominal Incision Infection after Colorectal Surgery in a Saudi Arabian Population: The Method of Surveillance Matters

BACKGROUND Reported surgical site infection rates range from 2.1% to 40% after colorectal surgery and are believed to be underestimated depending on the method of surveillance. The study aims were to identify an accurate incidence and associated risk factors for abdominal incision surgical site infection after elective open colorectal surgery in a Saudi population. METHODS This was a prospective observational longitudinal study of 300 consecutive adult patients, recruited upon admission to an 800-bed tertiary referral center. All consenting adults admitted for elective open colorectal surgery were included. Patients were followed for 36 d post-surgery by two certified and experienced wound care experts who diagnosed abdominal incision surgical site infections. The definition provided by the U.S. Centers for Disease Control and Prevention was used. Statistical analysis was performed using both univariate and multivariable logistic regression. RESULTS Data were analyzed for 296 patients; the incidence of abdominal surgical site infection was 30%. Factors associated with surgical site infection by univariate analysis were pre-operative pre-albumin (p=0.04, odds ratio [OR] 0.81, 95% confidence interval [CI] 0.66-0.99); operative difficulty because of truncal obesity (p=0.006, OR 2.19, 95% CI 1.25-3.84) and obesity measured by body mass index (p=0.002, OR 4.00, 95% CI 1.95-8.20). Multivariable analysis identified only two significant risk factors: Pre-operative pre-albumin (p=0.02, OR 0.76, 95% CI 0.60-0.96), and obesity measured by body mass index (BMI; p=0.001, OR 4.71, 95% CI 2.20-10.10). CONCLUSION Obesity and nutritional status correlated with post-operative abdominal surgical site infection. The method of surveillance and length of follow-up impact the rate reported.

Outcome after ileal pouch-anal anastomosis for familial adenomatous polyposis compared to mucosal ulcerative colitis in a Middle Eastern population.

BACKGROUND AND OBJECTIVES To compare the complications and outcome after ileal pouch-anal anastomosis (IPAA) for mucosal ulcerative colitis (MUC) and familial adenomatous polyposis (FAP). DESIGN AND SETTINGS This is a retrospective study. The study was conducted at a single tertiary referral center. METHODS All patients who underwent restorative proctocolectomy with IPAA at a tertiary center in Saudi Arabia from 2001 till 2009 were retrieved. Data was obtained regarding preoperative status, postoperative complications, and functional outcome. RESULTS A total of 40 patients underwent IPAA, of which 21 cases were of FAP and 19 cases of MUC. Median age at operation for FAP and MUC was 31 (range: 16–45) and 43 (range: 15–65) years, respectively (P<.05). Median length of stay was 10 days (range: 6–42) for FAP and 12 days (range: 9–27) for MUC (P=.1). Postoperative morbidity was noted in 4 cases of FAP and 6 cases of MUC (P=.36). Specifically, wound infection was noted in 2 cases of FAP compared to 3 cases of MUC (P=.55); 1 MUC case had an anastomotic leak (P=.29). One mortality was recorded among the FAP cases (P=.35). The time between the creation of IPAA and the closure of ileostomy was 4.5 and 5 months for FAP and MUC, respectively (P=.87). Median follow-up was 36 months. Median bowel frequency per 24 hours was 6 (range: 3–24) for FAP and 7 (range 3–17) for MUC (P=.54). Intestinal obstruction was reported in 3 cases of FAP and 5 cases of MUC (P=.38). One pouch was excised in a FAP patient. One case of MUC developed pouchitis. CONCLUSIONS The outcome after IPAA was inferior for MUC compared to FAP, but it was not statistically significant due to the small sample size. The morbid status of the MUC cases and their older age contributed to the minor differences.

Expanding the spectrum of germline variants in cancer

Our ability to identify germline variants in hereditary cancer cases remains challenged by the incomplete cataloging of relevant genes and lack of consensus on who should be tested. We designed a panel [hereditary oncogenesis predisposition evaluation (HOPE)] that encompasses most of the genes known to be associated with cancer development and tested its yield on more than 1300 samples of cancer patients. Pathogenic or likely pathogenic variants in high and intermediate risk genes were identified in 16, 23.9, 9.7 and 2.7%, respectively, of peripheral blood or normal tissue samples taken from patients with breast, ovarian, colorectal and thyroid cancer. To confirm specificity of these findings, we tested an ethnically matched cohort of 816 individuals and only identified pathogenic or likely pathogenic variants in 1.59% (0.98% in high risk and 0.61% in intermediate risk). Remarkably, pathogenic or likely pathogenic alleles in DNA repair/genomic instability genes (other than BRCA2, ATM and PALB2) accounted for at least 16.8, 11.1, 50 and 45.5% of mutation-positive breast, ovarian, thyroid and colorectal cancer patients, respectively. Family history was noticeably lacking in a substantial fraction of mutation-positive cases (63.7, 81.5, 42.4 and 87.5% in breast, ovarian, colorectal and thyroid, respectively). Our results show high contribution of germline mutations to cancer predisposition that extends beyond “classical” hereditary cancer genes. Family history was lacking in 63.5% mutation-positive cases, shows that hereditary cancer need not appear familial and suggests that relaxed selection of cancer patients for hereditary cancer panels should be considered.

Pre-operative chemoradiotherapy using capecitabine and cetuximab followed by definitive surgery in patients with operable rectal cancer

BACKGROUND Achieving a high rate of complete pathological response with pre-operative chemoradiotherapy in rectal cancer is an unmet need. We evaluated the efficacy and toxicity of the combination of cetuximab, capecitabine and radiation therapy in the pre-operative setting of localized rectal cancer. PATIENTS AND METHODS Patients with clinically staged T3, T4 or nodepositive rectal cancer were treated with concurrent capecitabine and radiotherapy with weekly cetuximab starting one week before the start of radiation. This was followed by total mesorectal excision within 6-8 weeks. All patients achieving R0 resection received adjuvant capecitabine for 6 cycles. RESULTS Fifteen patients were treated and all underwent surgery. Sphincter preservation was achieved in 11 patients (73.3%) and pathological complete response in two. With a median follow up of 48 months (range 8.4-57.5), 12 patients were relapse-free and 14 were alive with 4-year relapse free survival of 80%. Overall survival was 93%. Significant grade 3 and 4 toxicity was mainly cetuximab-induced skin reactions (33%), radiation-induced skin toxicity (13%) and diarrhea (20%). CONCLUSIONS Adding cetuximab to pre-operative concurrent capecitabine and radiotherapy provides modest efficacy with manageable toxicity.

Abstract 1213: Clinicopathological significance of ALK alterations in colorectal carcinoma.

ALK has been shown to be a putative oncogene in lung cancer and neuroblastoma that can be potentially targeted with selective inhibitors. Ongoing clinical trials using ALK inhibitors such as Crizotinib have shown promising results. ALK gene copy gain number in colorectal cancer (CRC) patients have been shown to be associated with tumors that have a more aggressive phenotype. We investigated the alterations in ALK gene by FISH analysis, immunohistochemistry and screened for ALK mutations by sequencing the ALK gene in 737 CRC. We screened for mutations in ALK by sequencing the tyrosine kinase domain that covers exons 20 -28. ALK alterations were correlated with tumor pathological features including TNM staging, MSI status, KRAS and BRAF mutations, as well as clinical outcome. Overall survival was analyzed using Kaplan Meyer plots. On FISH analysis in colorectal cancers, ALK amplifications were observed in 2.6%. Amplifications and gain with increase in gene copy number(4 to 6 copies) were seen in 3.4%. No translocations were seen in our study. There were no associations with nodal metastasis and other clinical or molecular parameters. However in Stage III & IV, ALK amplification was associated with KRAS mutations. CRC subgroup with ALK amplifications showed a poor overall survival overall survival and ALK gene amplifications was an independent prognostic marker in multivariate Cox proportional Hazards model. IHC showed cytoplasmic overexpression in 14.7% CRCs and no associations with any clinical or molecular parameters. We are screening for ALK mutations in 100 CRC samples and results are awaited. The insights gained from our current study and future clinical trials are likely to directly benefit subgroups of CRC patients whose tumors are driven by ALK and will pave the way to more targeted approaches to cancer treatment. Citation Format: Zeenath Jehan, Sarita Esther Prabhakaran, Rong Bu, Nasser Al-Sanea, Alaa Abduljabbar, Luai Ashari, Samar Al-Homoud, Fouad Al Dayel, Shahab Uddin, Prashant Bavi, Khawla Sami Al-Kuraya. Clinicopathological significance of ALK alterations in colorectal carcinoma. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1213. doi:10.1158/1538-7445.AM2013-1213

Abstract 1069: Clinicopathological significance of CARD10 alterations in Middle Eastern colorectal cancer

The incidence of Colorectal Carcinoma (CRC) in Saudi Arabia is rising and CRC is among the top 3 Saudi cancers in both men and women. NF-κB gene plays a role in tumorgenesis through the transcriptional activation of genes associated with cell proliferation, angiogenesis, metastasis, tumor promotion, inflammation and suppression of apoptosis. NF-κB protein activation, defined as nuclear expression of NF-kB by immunohistochemistry was seen in 43.2% (164/380) CRC and was an independent prognostic marker for poor survival. CARD10 and A20 genes are known positive and negative regulators of the NF-kB activation pathway and can activate the NF-kB activity. CARD10 is an enzyme that is encoded by the CARD10 gene and it associates with IKK complex resulting in NF-κB activation. CARD11 which shares a high degree of structure, domain and functional homology to CARD10 is oncogenic in diffuse large B cell lymphoma and results in activation of NF-κB. Considering the potential therapeutic utility of targeting NF-kB and its key modulators, we studied CARD10 genetic alterations (mutations and amplifications) and immunohistochemical expression of CARD10 in over 300 CRC cases and 13 colon cell lines. We detected missense mutations in 5.2 % (15/288) and 2 colon cell lines. Our results showed that CARD10 protein is widely expressed in CRC (67.7%) and expression levels of CARD10 progressively increase from normal colorectal mucosa to pre-malignant colorectal adenomas to CRC. CARD10 protein expression associated significantly with NF-KB activation (P = 0.0313). Interestingly, there was a mutual exclusivity between CARD10 protein overexpression and A20 loss of expression which might suggest that NFKB can be activated by alteration in one of these genes in CRC. Furthermore, CARD10 amplification (15.3%) was significantly associated with CARD10 protein expression and presence of distance metastasis (p=0.0487) Interestingly CARD10 mutations were detected in 21.4% of MSI CRC and only 78.6% of MSS CRC (p=0.0251), suggesting that CARD10 mutations play a role in both subsets of CRC but might represent more important oncogenic event for the development/progression of MSI CRC than MSS CRC. Our study highlights for the first time the role of CARD10 protein overexpression as a novel mechanism for NF-kB activation and demonstrates clinico-pathological significance of CARD10 alterations in Middle Eastern CRC. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 1069. doi:10.1158/1538-7445.AM2011-1069