presence of opportunistic pathogens such as Fusobacterium nucleatum, which in turn could be responsible, at least in part, of the higher levels of inflammation found in these patients.These data point out the importance that gut microbiota could have in the appearance and develpment of CRC-associated to obesity and could give new clues for the development of new diagnostic tools for CRC prevention.

Background: For patients who are diagnosed with early-stage cutaneous melanoma, the principal therapy is wide surgical excision of the primary tumour and assessment of lymph nodes. The purpose of the present guideline was to update the 2010 Cancer Care Ontario guideline on wide local excision margins and sentinel lymph node biopsy (slnb), including treatment of the positive sentinel node, for melanomas of the trunk, extremities, and head and neck. Methods: Using Ovid, the medline and embase electronic databases were systematically searched for systematic reviews and primary literature evaluating narrow compared with wide excision margins and the use of slnb for melanoma of the truck and extremities and of the head and neck. Search timelines ran from 2010 through week 25 of 2017. Results: Four systematic reviews were chosen for inclusion in the evidence base. Where systematic reviews were available, the search of the primary literature was conducted starting from the end date of the search in the reviews. Where systematic reviews were absent, the search for primary literature ran from 2010 forward. Of 1213 primary studies identified, 8 met the inclusion criteria. Two randomized controlled trials were used to inform the recommendation on completion lymph node dissection. Key updated recommendations include: (1) Wide local excision margins should be 2 cm for melanomas of the trunk, extremities, and head and neck that exceed 2 mm in depth. (2) SLNB should be offered to patients with melanomas of the trunk, extremities, and head and neck that exceed 0.8 mm in depth. (3) Patients with sentinel node metastasis should be considered for nodal observation with ultrasonography rather than for completion lymph node dissection. Conclusions: Recommendations for primary excision margins, sentinel lymph node biopsy, and completion lymph node dissection in patients with cutaneous melanoma have been updated based on the current literature.

# 01: Iron deficiency in bariatric surgery patients — a single-centre experience over 5 years {#article-title-2} As the prevalence and severity of obesity have increased in Canada, so too has the demand for bariatric surgery. The objective of this study was to determine the incidence of

Background: Advances in chemotherapy for mCRC have improved median survival to more than 24 months. This has resulted in increased opportunity to undergo more frequent interventions for symptom relief at the end of life. We explored patterns of palliative interventions (surgery, endoscopy, interventional radiology (IR), drainage procedures, radiotherapy) in mCRC patients over a time of evolving chemotherapy regimens. Methods: A retrospective review was undertaken of all mCRC patients referred to palliative care at a tertiary cancer center in Toronto, Canada. Patients treated 2000-2004 (early cohort) were compared to 2006-2010 (later cohort) as more effective palliative chemotherapy was available in the later time period. Descriptive statistics, t-tests, and chi-squared tests were employed. Results: A total of 542 (212 early and 330 later cohort) patients were included. Compared to the early cohort, the later cohort was significantly younger (62 vs 65 years, p = 0.012), had more Stage 4 disease (47 vs 42%, p = 0.029), fewer curative surgeries (58 vs 70%, p = 0.005) and fewer had adjuvant chemotherapy (26 vs 38%, p = 0.002). Palliative care referral was delayed for the later cohort with longer times between diagnosis of unresectability and referral (13 vs 8 mths, p = 0.0019) and shorter times between referral and death (6 vs 8 mths, p = 0.019). More patients in the later cohort had palliative surgery (31 vs 22%, p = 0.015), palliative IR procedures (15 vs 4%, p < 0.0001) and did not receive any chemotherapy (44 vs 29%, p < 0.0001). The later cohort underwent more interventions in the last months of life with more chemotherapy and drainage procedures closer to death (7 vs 12 mths, p = 0.002 and 2 vs 9 mths, p = 0.006 respectively). There was no difference in survival (calculated from date of diagnosis to death) between the cohorts (median survival 35 months). Conclusions: In their final months of life, palliative mCRC patients are undergoing more interventions requiring multi-disciplinary input with the aim of improving quality of life than previously. Increasing use of interventions in the last months of life has significant ramifications for patients, service provision, staffing and funding. Funding: PSI Foundation Disclosure: All authors have declared no conflicts of interest. Keywords: palliative interventions, metastatic colorectal cancer, palliative care

# 1 Is laparoscopic sleeve gastrectomy a reasonable stand-alone procedure for super morbidly obese patients? {#article-title-2} Laparoscopic Roux-en-Y gastric bypass (LRYGB) is a well established standard of care in the treatment of obesity and its associated comorbidities. Laparoscopic sleeve