586P - Estimation of risk of nodal involvement following pre-operative chemoradiotherapy for locally advanced rectal cancer with view to organ preservation

Date 29 September 2014
Event ESMO 2014
Session Poster Display session
Topics Anti-Cancer Agents & Biologic Therapy
Rectal Cancer
Surgery and/or Radiotherapy of Cancer
Presenter Fei Sun
Citation Annals of Oncology (2014) 25 (suppl_4): iv167-iv209. 10.1093/annonc/mdu333
Authors F. Sun, A.S. Dhadda
  • Oncology, Castle Hill Hospital, HU16 5JQ - Hull/GB

Abstract

Aim

Locally advanced rectal cancer is routinely treated with neo-adjuvant chemoradiotherapy to downstage the disease prior to surgery. The ypT stage correlates with risk of nodal involvement. We proposed the use of tumour regression grade in addition to this to determine whether it could predict a cohort of patients who could be treated with local excision alone.

Methods

The study involved 261 patients with locally advanced rectal cancer treated with pre-operative chemo-radiotherapy between 2001 and 2009 at Nottingham University Hospital and the Queen's Centre for Oncology in Hull. All patients were treated with CT planned conformal radiotherapy with a dose of 45-50Gy in 25 fractions with or without concurrent fluoropyrimidine chemotherapy. Surgery was performed after an interval of 6-10 weeks. The tumour regression grade (TRG) was assessed by two pathologists using the Mandard score.

Results

A simplified Mandard TRG grading system was used, TRG1(complete regression), TRG2(microscopic residual cancer) and TRG3(Mandard TRG 3-5 ranging from significant residual disease to no regression). The demographics of the patients is shown in table 1. Of the 261 patients 38 had T0, 15 patients had ypT1, 43 patients had ypT2, 152 patients had ypT3 and 13 patients had ypT4 disease. On chi-square analysis T stage, lymphovascular invasion (LVI) and TRG were significantly associated with risk of pathological nodes (p < 0.0001). The risk of pathological nodes for patients downstaged to ypT0-1 was 2%, ypT2 12%, ypT3 46% and ypT4 62% (see table 2). For patients without LVI who were downstaged to ypT2 the risk of pathological nodes was 8% for TRG2 and 17% for TRG3.

Conclusions

Patients who are downstaged to ypT0-1 following standard pre-operative chemoradiotherapy have a low risk of pathological nodal metastases and may benefit from a local excision with a view to organ preservation. Patients downstaged to ypT2 or above have a high risk of nodal disease greater than 12% although a subgroup of ypT2 with no LVI and TRG2 warrants further investigation.

Disclosure

All authors have declared no conflicts of interest.