P-0282 Facing Rectal Cancer Under the Age of 50: Analysis of 140 Patients Discussed in an Multidisciplinary Team (Co-Recto) in Argentina

Abstract

ABSTRACT Introduction Recent studies have outlined an increase in the incidence rates of rectal cancer among adults aged 50 and younger, a group for whom average-risk screening is not a standard of care. Controversies still exist regarding its features and prognosis. Methods Between February-2007 and December-2011, 578 rectal cancer pts were registered and discussed in our multidisciplinary team “Co-Recto”. A retrospective cohort analysis was performed in a subset of adults aged ≤50 years, focusing on clinical and demographic parameters, preoperative assessment, therapeutic approach, tumor response and pattern of disease recurrence. Results 140/578 (24.2%) pts were aged between 18-50 years, of whom 82 (58%) were identified as being aged ≤40 at presentation. Median age was 37 years, 73/140 (52%) were female. Only 35/140 (25%) had medical insurance. The mean time from symptoms onset to diagnosis was 6 months (1-34 months). The most frequent tumor location was lower rectum: 74/140 (53%). Median distance from the anal verge was 50 mm (10–150 mm). Levator muscle - external anal sphincter were involved in 26/140 pts (18%). 26/140 (18%) tumors were single-ring cells- mucinous adenocarcinoma. Regarding colorectal cancer high-risk conditions, 9/140 (6.5%) pts had familial adenomatous polyposis and 8/140 (6%) had inflammatory bowel disease. Lynch syndrome was assessed in 23/140 (16%) pts with microsatellite instability (MSI) analysis and/or immunohistochemistry (IHQ) analysis of mismatch repair (MMR) proteins MLH1, MSH2, MSH6 and PMS2. 22/23 (96%) pts had MMR proficient tumors; in 1/23 pts (4%) a germinal mutation in PMS2 was identified (Lynch syndrome). 10/23 pts were also screened for the two most prevalent MUTYH mutations: G393D and Y176C, identifying biallelic MUTYH mutations in 1 case. 19/140 (13.5%) pts had already undergone elective surgery before discussion in “Co-Recto”, and 121/140 (86.5%) were assessed preoperatively in “Co-Recto” to decide the best therapeutic approach. Clinical staging at diagnosis was I: 6(5%), II 18(15%), III 66(54%) and IV: 31(26%). A curative intent therapeutic approach was done in 90/121 (74%). Neoadjuvant treatment was delivered in 61/90 (68%): induction chemotherapy 49/61 (80%), chemoradiotherapy mostly based on capecitabine 58/61 (95%), and chemotherapy alone followed by TME surgery 3/61 (5%). 2/61 pts with clinical complete response by MRI were considered for a watch and wait strategy, pathological complete response rate was 19% (11/59). After a median follow up of 23 months (2-54m), the recurrence rate was: local 2/61 (3.2%), distant 4/61 (6.5%), and both (1/61). Conclusion In our experience, young-onset rectal cancer frequently presents with locally advanced and/or metastatic disease, requiring more aggressive treatments. Distant relapses often occur. Known hereditary syndromes seem to have a low prevalence. We highlight the challenge of reviewing current screening strategies to warrant a proper and early diagnosis in young patients.