Relevance of adjuvant chemotherapy in elderly patients with low rectal tumors.

Abstract

37 Background: The balance between the benefits and toxicities of adjuvant systemic chemotherapy is crucial in the elderly, and often co-morbid patients who have undergone total mesorectal excision (TME) surgery for carcinomas of the lower rectum (1). Tumour distance from the anal verge is a known prognostic factor in rectal cancer (2, 3) and it may influence the effectiveness of adjuvant chemotherapy (AC) (4). This study evaluated the differences in the survival outcomes between patients on surveillance(S) and those who received AC in a multi-centre, real-world setting with a focus on the elderly cohort. Methods: Data was extracted from electronic patient records from 4 NHS trusts in Kent, UK. We retrospectively analysed records of patients between 1 Jan 2014 and 31 Dec 2019, who had neoadjuvant chemoradiotherapy, were down-staged and then offered either S or AC based on clinician’s judgement. The tumour distance from the anal verge was measured through high resolution MRI. The patients were downstaged following assessment as their pTNM staging was lower than their cTNM staging. Results: 589 patients treated for rectal cancer were identified. Of these, 168/589(28%) had non-metastatic disease, were later down-staged at TME and were offered S or AC. 95/168 (57%) of these patients received AC. Patients who received AC were younger (median age 63 vs 70 years, p< 0.001) and with additional poor prognostic factors such as extramural venous invasion EMVI+ (74 vs 39%, p= 0.001), circumferential resection margin CRM+ (89 vs 70% p = 0.001) and pathological nodal involvement (AJCC stage III disease) ( p< 0.001) (table) compared to those on S. Our findings did suggest that patients on surveillance with tumours < 5cm from the anal verge had a longer disease-free survival(DFS) than those who received chemotherapy; this was especially the case in the elderly patient cohort (HR 0.13 95% CI 0.02-0.99, p= 0.049).Our findings also showed that the DFS benefit for patients under surveillance increased with age. Surveillance was most effective in patients over 60 years old compared to those under 60. However, age or distance from anal verge did not have an impact on overall survival (HR 1.01 95% Cl 0.95-1.08 p= 0.70). Conclusions: Although patients treated with AC were younger than patients on S, their tumours had additional poor prognostic factors. Patients on surveillance with tumours <5cm from the anal verge enjoyed a longer DFS but no OS benefit. Elderly patients with tumours < 5cm from the anal verge with no poor prognostic features could derive a benefit from surveillance and avoid chemotherapy-related toxicity. However, our findings will need to be corroborated in prospective studies. [Table: see text]