Outcomes of younger patients diagnosed with locally advanced rectal cancer.

Abstract

500 Background: The incidence of rectal cancer is higher in the older population. In developed nations there has been a rise in incidence in young onset rectal cancer (yRC). We evaluated and compared the presentation and survival outcomes of treatments for locally advanced rectal cancer in yRC patients to that of older patients. Methods: All cases of rectal cancers referred to a large tertiary referral cancer centre in Western Sydney between 2009-2016 were examined. Patient demographics, presenting symptoms, treatment, clinico-pathological characteristics, progression free survival (PFS) and overall survival (OS) were obtained. Under 50 years old was used as the cut-off age for defining yRC. Results: One hundred sixty-two patients were identified, 33 in the yRC and 129 in the older patient group. The median age at diagnosis was 62 (24 – 92). Median follow-up was 40 months. There was no difference in presenting symptoms between the two groups, with per rectal bleeding being the most common symptom at presentation. 17.5% of yRC presented with stage IV disease, compared with 22.1% of older patients. yRC were more likely to complete neoadjuvant therapy (97% vs 81%; P=0.02). yRC were more likely to proceed to surgery (91% vs 72%, P=0.02). There were no significant differences in surgical outcomes, including complications and postoperative TNM staging. yRC were more likely to have microsatellite high tumours (18% vs 4%; P=0.01). No statistical differences were seen in survival outcomes (PFS 57.1 vs 62.9 months, P=0.26; OS 85.1 Vs 92.8 months, P=0.57) between older and yRC patients. Eight progressions (eight deaths) were observed in the yRC group and 40 progressions (36 deaths) were observed in the older patient group. Conclusions: 20% of rectal cancers were considered yRC. These patients were more likely to complete neoadjuvant therapy and proceed to surgery. In this cohort, median PFS and OS were longer compared to the older patient group, although this was not statistically significant. yRC were more likely to have MMR deficiency. Patients under 50 years with alarm symptoms including per rectal bleeding require vigilance in investigations to allow for earlier detection and appropriate management of rectal cancer.