Retrospective Evaluation of the Impact of Dose Escalation Using Pre-operative Simultaneous Integrated Boost Volumetric Modulated Arc Therapy on the Outcome of Locally Advanced Rectal Cancer Patients

PURPOSE

Evaluating the outcome of pre-operative simultaneous integrated boost volumetric modulated arc therapy (SIB-VMAT) concomitant with capecitabine in patients diagnosed with locally advanced rectal cancer (LARC) at King Faisal Specialist Hospital and Research Centre (KFSH&RC), Riyadh, Saudi Arabia, during the period January 2013-December 2019.

RESULTS

A total of 134 patients were enrolled. The median age at diagnosis was 59 years. All patients received pre-operative concurrent chemo-radiation therapy (CCRT) using SIB-VMAT with oral capecitabine. Neoadjuvant chemotherapy was administered prior to CCRT in 32 patients (23.9%). The dose of radiation was 55 Gy in 94 patients (70.1%), while 40 patients (29.9%) received 50 Gy. All patients completed the CCRT treatment without breaks. No records of acute and late grade III and IV toxicities. Curative surgery was performed in all patients with a median interval of 11 (6-52) weeks between the end of CCRT and the date of surgery. No reported 30-day postoperative mortality and no grade III and IV Clavien-Dindo complications. PCR was reported in 26 patients (19.4%), while pathologically negative nodes (pN0) were achieved in 103 patients (76.9%). Adjuvant chemotherapy was utilized in 57 patients (42.5%). The 5-year local recurrence-free survival (LRFS), disease-free survival (DFS), and overall survival (OS) were 93.2%, 67.1%, and 87.3%, respectively. Only tumor regression grade (TRG) was significantly correlated with LRFS, (p value 0.043). On multivariate analysis, only TRG and achievement of pN0 were significantly correlated with DFS (p value < 0.001).

CONCLUSION

Dose escalation utilization (SIB-VMAT) in the pre-operative treatment of LARC is well tolerated and provides effective local control.

Perianal extramammary Paget's disease with adenocarcinoma of perianal skin area, a case report

Extramammary Paget disease (EMPD) is an uncommon slow-growing skin adenocarcinoma originating in the anogenital region and axilla outside the mammary glands, often in regions with apocrine glands. The most common location is the vulva, followed by perineal, perianal, scrotal and penile skin. Here, we report a case of a 63-year-old male with EMPD in the perianal region. He reported 4 years of pain associated with an increasing region of skin irritation and bleeding on defecation that did not improve with topical agents. A biopsy sample revealed poorly differentiated carcinoma consistent with adenocarcinoma and associated with Paget disease. Workup was done. The patient tolerated local excision of the region well with no complications. A rare disease, EMPT, is challenging to diagnose and manage. Histopathological findings can, however, differentiate it from a wide array of similar skin conditions. Thorough investigations should be undertaken before initiating treatment to ensure the best outcomes.

Deterioration in renal function after stoma creation: a retrospective review from a Middle Eastern tertiary care center

BACKGROUND

Stomas are associated with multiple complications including dehydration which ultimately affects renal function. These complications begin with changes in the estimated glomerular filtration rate (GFR).

OBJECTIVES

Evaluate changes in GFR after stoma creation by stoma type and identify how different types of stoma affect GFR.

DESIGN

Retrospective, analytical cohort SETTING: Tertiary care center in Saudi Arabia PATIENTS AND METHODS: The colorectal surgery database was reviewed for all adult patients who underwent stoma creation (permanent and temporary ileostomies and colostomies) or reversal in 2000-2015. GFR was estimated at the first encounter, before the index surgery, at the time of stoma reversal, and upon the last follow-up. Patients with renal impairment, including low GFR before stoma creation, patients who had a temporary stoma converted to a permanent stoma, and patients who died with a stoma were excluded. We studied the association of several demographic and clinical factors on changes in GFR by univariate and multivariate analysis.

MAIN OUTCOME MEASURES

Estimated GFR at the last clinic visit for the permanent stoma group and at stoma closure for the temporary stoma group.

SAMPLE SIZE

394 patients (149 ileostomates, 245 colostomates) RESULTS: Thirty-three (8.4%) of the 394 patients had a low GFR: 11 (7.4%) in the ileostomy group and 22 (9%) in the colostomy group (P= .579). The rate of readmissions with ileostomies was higher (11.4%) than with colostomies (3.3%) (P≤.001). The number of temporary ileostomies (n=9, 7.0%) differed from temporary colostomies (n=2, 1.9%) but the difference was not statistically significant (P=.06). In the multivariate analysis, stoma permanency, hypertension, chemotherapy and nephrotoxic drugs were risk factors associated with low GFR.

CONCLUSION

Ileostomies were not associated with a high rate of renal function deterioration in comparison to colostomies, but had a significantly higher rate of readmission due to dehydration and electrolytes imbalance possibly due to the hot climate in Saudi Arabia.

LIMITATIONS

Retrospective nature and limited sample size which may have resulted in a type 2 statistical error.

CONFLICTS OF INTEREST

None.

Neoadjuvant concurrent chemoradiotherapy using infusional gemcitabine in locally advanced rectal cancer: A phase II trial

INTRODUCTION

Gemcitabine is a well-known radiosensitizer. Herein, we tested the efficacy and toxicity of preoperative concurrent infusional gemcitabine and radiotherapy in locally advanced rectal cancer.

PATIENTS AND METHODS

This was a phase II, single-arm trial. Eligible patients had a diagnosis of rectal adenocarcinoma with clinical stage T3-T4 and/or nodal involvement, age ≥18 years, and no prior chemotherapy or radiotherapy. Patients received preoperative radiation at a dose of 50.4-54 Gy over 28 days with concurrent infusional gemcitabine administered at a dose of 100 mg/m² over the course of 24 h weekly for 6 weeks. The primary endpoint was pathological complete response (pCR).

RESULTS

Forty patients were recruited. Only one patient did not complete therapy due to death. Eight patients did not undergo surgery, one died, two progressed to nonresectable disease, and five withdrew consent. Five patients progressed prior to surgery, with two having unresectable metastases and three having resectable liver metastases. One was found to have peritoneal metastasis during surgery. Out of the 32 patients who underwent surgery, seven achieved pCR at a rate of 20%. With a median follow-up of 30 months, four additional patients had a distant relapse (one had a subsequent local relapse). The 3-year event-free and overall survival rates were 70% and 85%, respectively. The commonest preoperative grade 3-4 toxicity included lymphopenia (50%), neutropenia (41%), anemia (15%), diarrhea (12%), abdominal pain (12%), and proctitis (8%).

CONCLUSION

Concurrent preoperative chemoradiotherapy using infusional gemcitabine for locally advanced rectal cancer achieved an encouraging degree of local control with manageable toxicity.

Sacral chordoma with incidental rectal adenocarcinoma: a case report

Background

We report a unique case of synchronous sacrococcygeal chordoma in association with rectal invasive adenocarcinoma. Retrorectal tumors are a rare disease caused by a variety of pathologies. To our knowledge, no prior cases of such a coincidental finding of both cancers have been reported in the literature.

Case presentation

This is the case of a 74-year-old white middle eastern man, with known hypertension under treatment, who presented with complaints of progressive lower back pain associated with urinary incontinence over the past 12 months. Magnetic resonance imaging (MRI) of the pelvis showed a large midline, well-defined, oval-shaped lesion replacing the sacrococcygeal portion of the spine, with extension to the presacral region. Computed tomography (CT)-guided Tru-Cut biopsy revealed features suggestive of chordoma. At surgery, we performed excision of the entire mass en bloc, sacrectomy with rectus abdominis myocutaneous flap reconstruction and end sigmoid colostomy. Surgical histopathology proved it to be sacral dedifferentiated chordoma and rectal invasive adenocarcinoma. Overall, the patient recovered well postoperatively, was discharged home with functional stoma and on permanent Foley catheter use.

Conclusion

To the best of our knowledge, this is the only reported case of such a presentation, and sheds light on the approach and management. We hope that reporting such a case will add value to the medical literature.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13256-021-02728-2.

Clonal Evolution and Timing of Metastatic Colorectal Cancer

Colorectal cancer (CRC) is the third most frequently diagnosed cancer worldwide, where ~50% of patients develop metastasis, despite current improved management. Genomic characterisation of metastatic CRC, and elucidating the effects of therapy on the metastatic process, are essential to help guide precision medicine. Multi-region whole-exome sequencing was performed on 191 sampled tumour regions of patient-matched therapy-naïve and treated CRC primary tumours (n = 92 tumour regions) and metastases (n = 99 tumour regions), in 30 patients. Somatic variants were analysed to define the origin, composition, and timing of seeding in the metastatic progression of therapy-naïve and treated metastatic CRC. High concordance, with few genomic differences, was observed between primary CRC and metastases. Most cases supported a late dissemination model, via either monoclonal or polyclonal seeding. Polyclonal seeding appeared more common in therapy-naïve metastases than in treated metastases. Whereby, treatment prompted for the selection of distinct resistant clones, through monoclonal seeding to distant metastatic sites. Overall, this study reinforces the importance of early clinical detection and surgical excision of the CRC tumour, whilst further highlighting the clinical challenges for metastatic CRC with increased intratumour heterogeneity (either due to early dissemination or polyclonal metastatic spread) and the underlying risk of future therapeutic resistance in treated patients.

POLE and POLD1 germline exonuclease domain pathogenic variants, a rare event in colorectal cancer from the Middle East

Background

Colorectal cancer (CRC) is a major contributor to morbidity and mortality related to cancer. Only ~5% of all CRCs occur as a result of pathogenic variants in well‐defined CRC predisposing genes. The frequency and effect of exonuclease domain pathogenic variants of POLE and POLD1 genes in Middle Eastern CRCs is still unknown.

Methods

Targeted capture sequencing and Sanger sequencing technologies were employed to investigate the germline exonuclease domain pathogenic variants of POLE and POLD1 in Middle Eastern CRCs. Immunohistochemical analysis of POLE and POLD1 was performed to look for associations between protein expression and clinico‐pathological characteristics.

Results

Five damaging or possibly damaging variants (0.44%) were detected in 1,135 CRC cases, four in POLE gene (0.35%, 4/1,135) and one (0.1%, 1/1,135) in POLD1 gene. Furthermore, low POLE protein expression was identified in 38.9% (417/1071) cases and a significant association with lymph node involvement (p = .0184) and grade 3 tumors (p = .0139) was observed. Whereas, low POLD1 expression was observed in 51.9% (555/1069) of cases and was significantly associated with adenocarcinoma histology (p = .0164), larger tumor size (T3 and T4 tumors; p = .0012), and stage III tumors (p = .0341).

Conclusion

POLE and POLD1 exonuclease domain pathogenic variants frequency in CRC cases was very low and these exonuclease domain pathogenic variants might be rare causative events of CRC in the Middle East. POLE and POLD1 can be included in multi‐gene panels to screen CRC patients.

A cutaneous metastasis of unresectable rectal adenocarcinoma: A case report and literature review

•

Colorectal cancer (CRC) is the third most commonly diagnosed malignancy and the fourth leading cause of cancer death in the world.

•

Approximately, 0.8% of patients will present with skin lesion as the first sign of a silent internal malignancy as skin metastasis without visceral metastasis is rare in CRC.

•

A comprehensive literature review (including clinical features of patients, management, and outcome) covering all reported cases of cutaneous metastasis secondary to rectal cancer was included for better understanding of the disease.

Background

Colorectal cancer is ranked third among the most commonly diagnosed malignancies and fourth among the leading causes of cancer death in the world. However, only a few case reports are found in the literature regarding skin metastasis originating from rectal cancer, which usually shows widespread disease and poor prognosis. Approximately, 0.8% of the patients will have skin lesion as the first indication of a silent internal malignancy, which is rare.

Case report

We report a complicated case of a 45-year-old male patient who referred to our highly specialized governmental hospital for diversion loop colostomy as well as biopsies of rectal and inguinal skin areas followed by palliative radiation therapy to the pelvis. Histopathological exam of rectal biopsies revealed moderately differentiated rectal adenocarcinoma, while the skin of the right inguinal area showed metastatic cutaneous rectal adenocarcinoma. Unfortunately, palliative radiation therapy was not started as the patient passed away secondary to respiratory failure which ended by cardiopulmonary arrest.

Conclusion

A patient who is having new or evolving skin lesions with an oncology history should be well investigated as cutaneous metastasis is a strong possibility.

Long-term outcomes after complete mesocolic excision for colon cancer at a tertiary care center in Saudi Arabia

BACKGROUND

Data on long-term survival and recurrence of cancer after complete mesocolic excision (CME) for colon cancer has not been reported from our center and related to international data.

OBJECTIVE

Describe overall and disease-free survival, survival by surgery site and stage, and recurrence rates after curative surgery.

DESIGN

Retrospective chart review.

SETTINGS

Academic tertiary care center.

PATIENTS AND METHODS

The study included all patients who underwent either laparoscopic or open surgery for colon cancer with curative intent between 2001 and 2011. The colorectal database was reviewed for the following: demographic data, comorbidities, radiologic investigations, clinical stage, type of operation, complications, pathologic assessment, adjuvant treatment, recurrence and survival. Survival and recurrence rates were calculated, and survival curves were generated.

MAIN OUTCOME MEASURES

5-year overall survival, secondary endpoints were 5-year disease-free survival, survival by surgery site and stage, and recurrence rates.

SAMPLE SIZE

220.

RESULTS

The mean (SD) age at diagnosis was 57 (13) years (CI 95%: 55-59 years). There were 112 males. Mean (SD) body mass index was 27.6 (5.7) kg/m² (CI 95%: 27-28). Pathological assessment revealed R0 (microscopically margin-negative) resection in 207 (94%). The overall 5-year survival and disease-free survival was 77.9% and 70%, respectively. The 5-year disease-free survival was 69% for the sigmoid/left colon and 69% for the right colon (difference statistically nonsignificant). Stages at the time of resection were stage 0 for 2 (0.01%) patients, stage I for 18 (8%), stage II for 92 (42%), stage III for 100 (46%), and stage IV for 6 (3%). The 5-year overall survival by stages I, II, III and IV was 94%, 80%, 75% and 50%, respectively (difference statistically non-significant). The overall 5-year recurrence rate was 23.4%.

CONCLUSION

The outcomes of surgical treatment for colon cancer at our institution are equivalent to international sites. No difference was noted between left and right colon in terms of survival after CME.

LIMITATIONS

Single center, retrospective, small sample size.

CONFLICT OF INTEREST

None.

APC truncating mutations in Middle Eastern Population: Tankyrase inhibitor is an effective strategy to sensitize APC mutant CRC To 5-FU chemotherapy

Colorectal Cancer (CRC) is highly heterogeneous for which prognosis is dependent mainly on clinical staging. There is a need to stratify subpopulations of CRC on molecular basis to better predict outcome and therapy response. Truncating mutations in adenomatous polyposis coli (APC) are well-described events in CRC carcinogenesis. Clinical and genotypic characterization of Middle Eastern CRC based on presence and type of APC was determined in 412 CRC tumors using modern next generation sequencing. APC truncating mutations were identified in 58.2% (240/412) of CRCs. Overall, mutation was significant predictor of superior overall survival. Further, the type of APC mutations (short or long) did not have impact on clinical outcome. However, in vitro analysis showed difference between CRC cell lines carrying short truncating APC vs CRC cells that carry long truncating APC mutation in response to 5-flourouracil (5-FU). Importantly, we were able to overcome the resistance to 5-FU seen in CRC cells carrying short APC by tankyrase inhibitor, XAV939, thereby inhibiting Wnt/β-catenin signaling cascade. Overall, our results showed that APC mutation status plays an important role in predicting overall survival in Middle Eastern population. Furthermore, in vitro data showed that selective targeting of APC mutated CRC by tankyrase inhibitor can be an effective strategy to overcome 5-FU resistance in CRC cells.

Abstract 4286: TGFβ induced SMAD4 dependent apoptosis proceeded by EMT in colorectal cancer

Colorectal cancer (CRC) is one of the leading cause of cancer-related deaths Worldwide. In Saudi Arabia, CRC is more aggressive and presents at younger age, warranting new treatment strategies. Role of TGFβ/Smad4 signaling pathway in initiation and progression of CRC is well documented. Current study examined the role of TGFβ/Smad4 signaling pathway in a large cohort of Saudi CRC, followed by in vitro analysis to dissect the dual role of TGFβ on inducing epithelial to mesenchymal transition (EMT) and apoptosis. In this study, we investigated Smad4 alterations and their association with clinicopathological outcomes in a large cohort of CRC samples using targeted capture sequencing, Fluorescent in-situ hybridisation and immunohistochemistry. Our study demonstrated high frequency of Smad4 alterations with low expression of Smad4 protein identifying a sub-group of aggressive CRC to be an independent marker for poor prognosis. Functional studies using CRC cells show that TGFβ induces Smad4 dependent EMT followed by apoptosis. Induction of mesenchymal transcriptional factors, Snail1 and Zeb1 was essential for TGFβ-induced apoptosis. Our results indicate that KLF5 acts as an oncogene in CRC cells regardless of Smad4 expression and inhibition of KLF5 is requisite for TGFβ-induced apoptosis. Furthermore, TGFβ/Smad4 signal inhibits the transcription of KLF5 that in turn switches Sox4 from tumor promoter to suppressor. A high incidence of Smad4 alterations were found in the Saudi CRC patients. Functional study results indicate that TGFβ induces Smad4 dependent EMT followed by apoptosis in CRC cells.

Citation Format: Pratheeshkumar Poyil, Abdul K. Siraj, Divya Sasidharan Padmaja, Sandeep Kumar Parvathareddy, Rong Bu, Tariq Masoodi, Yan Kong, Saravanan Thangavel, Saeeda Omer Ahmed, Nasser Al-Sanea, Luai H. Ashari, Alaa Abduljabbar, Samar Alhomoud, Fouad Al-Dayel, Khawla S. Al-Kuraya. TGFβ induced SMAD4 dependent apoptosis proceeded by EMT in colorectal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4286.

TGFβ-induced SMAD4-dependent Apoptosis Proceeded by EMT in CRC

Colorectal cancer is one of the leading causes of cancer-related deaths worldwide. In Saudi Arabia, colorectal cancer is more aggressive and presents at younger age, warranting new treatment strategies. Role of TGFβ/Smad4 signaling pathway in initiation and progression of colorectal cancer is well documented. This study examined the role of TGFβ/Smad4 signaling pathway in a large cohort of Saudi patients with colorectal cancer, followed by in vitro analysis to dissect the dual role of TGFβ on inducing epithelial-to-mesenchymal transition (EMT) and apoptosis. Our study demonstrated high frequency of Smad4 alterations with low expression of Smad4 protein identifying a subgroup of aggressive colorectal cancer to be an independent marker for poor prognosis. Functional studies using colorectal cancer cells show that TGFβ induces Smad4-dependent EMT followed by apoptosis. Induction of mesenchymal transcriptional factors, Snail1 and Zeb1, was essential for TGFβ-induced apoptosis. Our results indicate that KLF5 acts as an oncogene in colorectal cancer cells regardless of Smad4 expression and inhibition of KLF5 is requisite for TGFβ-induced apoptosis. Furthermore, TGFβ/Smad4 signal inhibits the transcription of KLF5 that in turn switches Sox4 from tumor promoter to suppressor. A high incidence of Smad4 alterations were found in the Saudi patients with colorectal cancer. Functional study results indicate that TGFβ induces Smad4-dependent EMT followed by apoptosis in colorectal cancer cells.

Survival and outcomes after laparoscopic versus open curative resection for colon cancer

BACKGROUND

Many studies have shown that open and laparoscopicsurgery for resection of colonic cancers produce similar short- and long-term results, but no data have been reported from Saudi Arabia.

OBJECTIVE

Compare 3-year disease-free and overall survival after laparoscopic versus open curative resection for potentially curable colon cancer.

DESIGN

Multicenter retrospective cohort study.

SETTING

Tertiary academic hospital.

PATIENTS AND METHODS

We analyzed data of patients who underwent curative resection for potentially curable colon cancer using the laparoscopic or open approach at three tertiary care centers during the period 2000-2015.

MAIN OUTCOME MEASURES

Overall and disease-free 3-year survival were the primary endpoints. Secondary endpoints included conversion rate, duration of surgery, length of hospital stay, rate of wound infection, resumption of bowel function, number of lymph nodes retrieved, adequacy of resection and rate of recurrence. Risk factors for recurrence, including complete mesocolic excision, were assessed.

SAMPLE SIZE

721.

RESULTS

Patient and tumor characteristics were similar in the two groups except for ASA class ( P<.01), weight ( P<.05) and tumor stage ( P<.05). Over a median follow-up of 46 months, the 3-year overall survival was 76.7% for open resection and 90.3% for laparoscopic colon resection ( P<.05). The 3-year disease-free survival was 55.3% for open colon resection and 64.9% for laparoscopic colon resection ( P=.0714).

CONCLUSION

Overall and disease-free survival after the laparoscopic approach for curative resection of colon cancer is comparable to the open approach.

LIMITATIONS

Retrospective design and the possibility of selection bias.

CONFLICT OF INTEREST

None.

Dose Escalation with Simultaneous Integrated Boost (SIB) Using Volumetric Modulated Arc Therapy (VMAT) in Rectal Cancer

PURPOSE

Assess feasibility-rate of PCR, short-term toxicity after neoadjuvant concurrent chemoradiation (NACRT) delivered via simultaneous integrated boost (SIB) using volumetric modulated arc therapy (VMAT) technique for locally advanced rectal cancer.

METHODS

Retrospective evaluation of patients with locally advanced rectal cancer treated with VMAT-SIB technique preoperatively at an academic tertiary care center in Riyadh, Saudi Arabia between February 2013 and March 2017.

RESULTS

One hundred patients with depth of invasion staged as T3/T4 or T2 in 93 and seven patients, respectively. Lymph node metastasis was staged as N1/N2 or N0 in 87 and 13 patients, respectively. Circumferential radial margin (CRM) was involved radiologically prior to treatment in 50 patients. A dose of 55 or 50 Gy was given to 71 and 29 patients, respectively. All treatments were completed without interruption. Grade 3/4 toxicity was not observed. Low anterior resection and abdominoperineal resection were performed with negative proximal, distal, and radial margins in 72 and 28 patients, respectively. There were no immediate significant postoperative complications. Histologically, no residual tumor (grade 0) was noted in 20 patients (pCR). Regression grade 1, 2, and 3 were noted in 31, 34, and 15 patients. Average number of lymph nodes retrieved in the surgical specimen was 12 (range 6-22). Lymph nodes were negative for cancer in 80 patients.

CONCLUSION

Dose escalation with SIB-VMAT as NACRT for rectal cancer is feasible. Moreover, it can increase the rate of pathological complete response with a favorable toxicity profile. Clinical benefit of this approach needs to be validated in a larger cohort of patients with longer follow-up.

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.

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.

Experience of assisted reproductive technology at King Abdulaziz University Hospital

AIM

To present the authors' experience with assisted reproductive technology (ART) at King Abdulaziz University Hospital in Jeddah, Saudi Arabia.

MATERIALS AND METHODS

Retrospective analysis of data collected from the charts of 264 women who were undergoing their first cycle of ART between September 2013 and March 2014. All the women were treated with gonadotropin-releasing hormone (GnRH) antagonist protocol. For all patients, the documented data included age, infertility type, cause, and hormone profile. Number of follicles > 10 mm, endometrial thickness, number of oocytes retrieved, number of fertilized ova, and number of embryos produced, as well as the number transferred, day of transfer, cancellation rate, and treatment administered for luteal phase support (oral and vaginal progesterone) treatment type, and outcome were recorded. The data was analyzed using the Statistical Package for the Social Sciences.

RESULTS

The authors included women aged 21 to 39 years (mean ± standard deviation, 32.28 ± 5.51). Patients suffered from primary infertility in 69.7% of the cases; approximately 30% of the women had secondary infertility. Eighty of the 264 patients (30.3%) conceived; however, only 56 women (21.2%) had a live birth. The overall cancellation rate in the patients was 12.1%. The following reasons were documented for cases of failure: no oocytes, 16 (6.1%); no sperm, eight (3.0%); and no embryo, eight (3.0%).

CONCLUSION

The success rate of ART at the present institution falls within the range reported in the medical literature. However, further studies should be conducted to investigate the course and outcome of ART in patients who undergo treatment in this institution.

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.

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

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

BACKGROUND

Infertility 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.

AIM

The 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.

METHODS

Charts 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.

RESULTS

During 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.

CONCLUSIONS

Laparoscopic 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.

Coexpression of activated c-Met and death receptor 5 predicts better survival in colorectal carcinoma

Dysregulated overexpression of hepatocyte growth factor and its receptor, c-Met, has been reported in various cancers, but its role in colorectal carcinoma (CRC) has not been elucidated. Therefore, we investigated the role of phosphorylated Met (p-Met) in Middle Eastern CRC patient samples and cell lines. The p-Met was overexpressed in 80.8% of CRCs and strongly associated with the expression of p-AKT, DR5, and Ki-67 by immunohistochemistry. Coexpression of p-Met and DR5 was seen in 53.1% of CRC cases and was associated with a less aggressive phenotype, characterized by a histological subtype of adenocarcinomas, well-differentiated tumors, and was an independent prognostic marker for better overall survival. PHA665752, a selective p-Met inhibitor, induced apoptosis in CRC cells via inactivation of c-Met and AKT. PHA665752 treatment also caused increased expression of DR5 via generation of reactive oxygen species, and combination treatment with tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) and PHA665752 induced significant apoptosis. In vivo, cotreatment of a CRC xenograft with PHA665752 and TRAIL significantly reduced tumor volume and weight. These data demonstrate a significant correlation between p-Met and DR5 in patients with CRC. Furthermore, inhibition of p-Met signaling by PHA665752 in combination with TRAIL significantly inhibited cell growth and induced apoptosis in CRC cell lines, suggesting that this may have significant clinical implications as a therapeutic target in the treatment of CRC.

Bortezomib stabilizes mitotic cyclins and prevents cell cycle progression via inhibition of UBE2C in colorectal carcinoma

Substantial evidence implicates the ubiquitin-conjugating enzyme E2C (UBE2C) gene, in several human cancers, including colorectal carcinoma (CRC). We therefore investigated the prognostic value of UBE2C alterations in CRC and UBE2C signaling in CRC cell lines. UBE2C protein expression and UBE2C gene copy number were evaluated on clinical samples by immunohistochemistry and fluorescence in situ hybridization in a TMA format. The effect of the proteasome inhibitor bortezomib and small-interfering RNA knockdown was assessed by apoptotic assays and immunoblotting. UBE2C dysregulation was associated with proliferative marker Ki-67, accumulation of cyclin A and B1, and a poor overall survival. UBE2C expression was an independent prognostic marker in early-stage (I and II) CRC. UBE2C depletion resulted in suppression of cellular growth and accumulation of cyclin A and B1. In vitro, bortezomib treatment of CRC cells caused inhibition of cell viability via down-regulation of UBE2C. UBE2C knockdown by bortezomib or transfection with specific small-interfering RNA against UBE2C also caused cells to be arrested at the G2/M level, leading to accumulation of cyclin A and cyclin B1. In vivo, a significant reduction in tumor volume and weight was noted in mice treated with a combination of subtoxic doses of oxaliplatin and bortezomib compared with treatment with oxaliplatin or bortezomib alone. Altogether, our results suggest that UBE2C and the ubiquitin-proteasome pathway may be potential targets for therapeutic intervention in CRC.

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

Abstract 4813: Aberrant promoter methylation of TMS1 gene in patients with colorectal carcinoma in Saudi Arabia

Gene silencing associated with aberrant methylation of promoter region CpG islands is an acquired epigenetic alteration. It serves as an alternative to genetic defects in the inactivation of tumor suppressor and other genes in human cancers. Several genes have been shown to be epigenetically inactivated in a wide range of tumors. TMS1 is a tumor suppressor gene which encodes for a CARD (caspase recruitment domain) containing regulatory protein and has been shown to be hyper-methylated in various cancers. Therefore, we studied the methylation status of TMS1 using a panel of colorectal cell lines and 15 CRC cases. Methylation status of the promoter region of TMS1 gene was determined using methylation specific PCR in colorectal cancer cell lines. Seven out of 13 colorectal cell lines showed to be methylated for TMS1 gene (54%). Initial analyses with 15 clinical colorectal cases demonstrated 53% methylation. Real time PCR and western bolt analysis was employed to assess the expression levels. 5-AZA-2′-deoxycytidine was used to demethylate colorectal cancer cell lines. Four out of 7 methylated colorectal cell lines were completely methylated and 3 out of 7 showed partial methylation for TMS1 gene resulting in loss of TMS1 expression. Treating methylated colorectal cell lines with the methyltransferase inhibitor, 5-aza-2’ deoxycytidine alone resulted in partial demethylation and re-expression of TMS1 gene, suggesting the role of methylation in silencing the gene. TMS1 gene has shown tumor suppressive effects after demethylation in thyroid cancer cell. Additionally the oncogenic role of TMS1 has been demonstrated in different cancers. We will further evaluate the role of TMS1 gene after demethylation for apoptosis. After demethylation of TMS1 gene with 5-aza-2’ deoxycytidine we will treat our colorectal cancer cell lines with increasing doses of TRAIL and will evaluate its response by Annexin/PI dual staining and western blot analysis.

Our results demonstrated that TMSI gene is methylated in colorectal cancer cells and repression of methylation by 5-Aza-2′-deoxycytidine restored the expression of TMS1 gene. In conclusion, methylation of TMS1 may prove to be a useful prognostic marker and/or predictor of patient survival in colorectal and can be utilized for targeted therapy.

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 4813. doi:10.1158/1538-7445.AM2011-4813

Abstract 2104: Frequent inactivation of A20 and its prognostic significance in Middle Eastern colorectal carcinoma

A20, also known as TNF alpha induced protein3 (TNFAIP3), is a tumor suppressor gene and a well-known negative regulator of the NF-kB pathway in hematolymphoid neoplasms. In colorectal carcinoma (CRC), aberrant NF-kB regulation has been associated with poor prognosis and resistance to therapy. However, role of A20 gene in CRC is unknown. Therefore, we sought to elucidate the biological role of A20, mechanism of its inactivation and its prognostic role in colorectal carcinoma. We investigated the genetic and epigenetic abnormalities of A20 gene in CRC. In a tissue microarray cohort of 434 CRC, we studied loss of A20 protein expression by immunohistochemistry and A20 deletions by FISH. We also screened 116 random CRC and 14 CRC cell lines for mutations in A20 gene and A20 promoter methylation. Of the 116 CRC samples, A20 deletions were seen in 15.3% and incidence of A20 mutation was 2.5%; most of the mutations (4/5) were missense mutations. A20 promoter hyper-methylation was seen in 50.8% and was correlated with loss of protein expression (p=0.0079). A20 inactivation, defined as loss or reduced expression of protein was observed in 63% of CRC and A20 inactivation was an independent prognostic marker for poor survival in all CRC. In addition A20 expression retained its prognostic value in the following subgroups: Stage III; Stage II and III; and Stage III and IV. A20 was inactivated in majority of the CRC due to promoter methylation and can be targeted to modulate NF-κb expression.

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 2104. doi:10.1158/1538-7445.AM2011-2104

Laparoscopic ovarian transposition before pelvic irradiation: a Saudi tertiary center experience

OBJECTIVE

To report the authors' experience with laparoscopic ovarian transposition and ovarian function preservation in women who require pelvic irradiation as part of their cancer therapy.

DESIGN

Cohort study.

SETTING

The gynecologic oncology service in a referral tertiary/quaternary medical center in Saudi Arabia.

PATIENTS

Twenty-three premenopausal patients treated with radiotherapy for a pelvic malignancy.

INTERVENTIONS

Laparoscopic ovarian transposition to paracolic gutters with uterine conservation.

MAIN OUTCOME MEASURES

Preservation of ovarian function assessed by patients' symptoms and serum follicle-stimulating hormone level.

RESULTS

Bilateral laparoscopic ovarian transposition was performed in 23 patients: 15 with cervical cancer, 4 with rectal cancer, 3 with Ewing sarcoma, and 1 with Hodgkin lymphoma. No immediate intraoperative or postoperative complications were observed. Three patients were lost to follow-up. Ovarian preservation was achieved in 13 (65%) of 20 patients. Seven patients with low follicle-stimulating hormone levels had regular uterine bleeding at follow-up.

CONCLUSIONS

Laparoscopic ovarian transposition is a safe and effective procedure for preserving ovarian function. This procedure should be considered in all premenopausal women who need to undergo pelvic irradiation as part of their cancer treatment.

Prognostic significance of TRAIL death receptors in Middle Eastern colorectal carcinomas and their correlation to oncogenic KRAS alterations

Background

Tumour necrosis factor-related apoptosis-inducing ligand (TRAIL) is a member of the tumour necrosis factor cytokine family that induces apoptosis upon binding to its death domain containing receptors, TRAIL receptor 1 (DR4) and TRAIL receptor 2 (DR5). Expression of TRAIL receptors is higher in colorectal carcinoma (CRC) as compared to normal colorectal mucosa and targeted therapy with TRAIL leads to preferential killing of tumor cells sparing normal cells.

Methods

We investigated the expression of TRAIL and its receptors in a tissue microarray cohort of 448 Middle Eastern CRC. We also studied the correlation between TRAIL receptors and various clinico-pathological features including key molecular alterations and overall survival.

Results

CRC subset with TRAIL-R1 expression was associated with a less aggressive phenotype characterized by early stage (p = 0.0251) and a histology subtype of adenocarcinomas (p = 0.0355). Similarly CRC subset with TRAIL-R2 expression was associated with a well-differentiated tumors (p < 0.0001), histology subtype of adenocarcinomas (p = 0.0010) and tumors in left colon (p = 0.0009). Over expression of pro apoptotic markers: p27^KIP1 and KRAS4A isoforms was significantly higher in CRC subset with TRAIL-R1 and TRAIL-R2 expression; TRAIL-R1 expression was also associated with cleaved caspase-3(p = 0.0011). Interestingly, TRAIL-R2 expression was associated with a microsatellite stable (MS--S/L) phenotype (p = 0.0003) and with absence of KRAS mutations (p = 0.0481).

Conclusion

TRAIL-R1 expression was an independent prognostic marker for better survival in all CRC samples and even in the CRC group that received adjuvant therapy. The biological effects of TRAIL in CRC models, its enhancement of chemosensitivity towards standard chemotherapeutic agents and the effect of endogenous TRAIL receptor levels on survival make TRAIL an extremely attractive therapeutic target.

Frequent PIK3CA gene amplification and its clinical significance in colorectal cancer

Using a DNA microarray approach to screen for gene copy number changes in 20 colorectal (CR) carcinoma samples and filtering for high-level DNA copy number changes, we detected an amplicon at 3q26 containing the PIK3CA gene. Fluorescence in situ hybridization was employed for evaluation of PIK3CA amplification on a progression CR tissue microarray containing 448 CR carcinomas, normal mucosa, and adenomas with follow-up information. PIK3CA amplification (ratio PIK3CA/centromere 3 > or = 2.0) was found in 38% of cancers, while another 19% of tumours had PIK3CA gains (ratio >1.0 but <2.0). Both PIK3CA amplification and gains were associated with high levels of PIK3CA protein expression and no association was seen between PIK3CA amplification and PIK3CA mutation. In a subset of 220 patients who received adjuvant chemotherapy and/or radiotherapy, survival in patients with PIK3CA-amplified cancers was significantly longer compared with patients with cancers without amplification. This association was independent of stage, grade, histology subtype, gender, and age categories. Interestingly, PIK3CA amplification was also seen in CR adenomas, indicating an early genetic alteration, and was also a frequent event in colorectal carcinogenesis. Furthermore, PIK3CA amplification is an independent prognostic marker for better survival and may be one of the promising markers to define CRC subsets that may maximally benefit from adjuvant therapy.

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.

Leptin receptor expression in Middle Eastern colorectal cancer and its potential clinical implication

We investigated the role of leptin receptor (Ob-R) and its relationship with phosphatidylinositol 3-kinase (PI3K)/AKT activation in colorectal carcinomas (CRCs) tissues followed by in vitro studies using a panel of CRC cell lines. Obesity serves an important risk factor of several cancers including CRC that ranks as the second most common cancer in Saudi Arabia. High levels of adipokine leptin (Ob) and its Ob-R are seen in obesity and also in various carcinomas including CRC. We investigated the proliferative and antiapoptotic effect of Ob on human CRC cell lines Caco-2, HT-29 and SW-840 and the role of PI3K/AKT-signaling pathway in mediating these actions. Then the expression of Ob-R and its relationship with clinicopathological features was analyzed in 448 CRC, 229 normal colon mucosa and 24 colorectal adenomas using tissue microarray technology. Treatment with Ob resulted in increased proliferation of CRC cell lines and involved activation of PI3K/AKT-signaling pathway. Pretreatment with Ob-R small interfering RNA or PI3K inhibitor inhibited these responses. Ob-R was significantly overexpressed in primary CRC relative to adenomas and normal colonic mucosa. In primary CRC, Ob-R significantly correlated with Ob expression, early stage and well-differentiated tumors. Intriguingly, patient with Ob-R positive tumors showed significantly better overall survival (P = 0.0098). Ob plays a critical role in CRC carcinogenesis through PI3K/AKT pathway via Ob-R. Ob-R is a prognostic marker associated with better survival.