573P - Relevant upstaging of pN2 cM0 colorectal cancer patients with post-surgery 18F-FDG PET-CT

Date 29 September 2014
Event ESMO 2014
Session Poster Display session
Topics Colon Cancer
Rectal Cancer
Imaging, Diagnosis and Staging
Presenter Martin Fehr
Citation Annals of Oncology (2014) 25 (suppl_4): iv167-iv209. 10.1093/annonc/mdu333
Authors M. Fehr1, J. Müller2, D. Horber3, D. Köberle4, T.T. Cerny5, U. Gueller1
  • 1Medical Oncology And Haematology, Kantonsspital St. Gallen, 9007 - St. Gallen/CH
  • 2Departement Nuclear Medicine, Kantonsspital St. Gallen, CH-9007 - St. Gallen/CH
  • 3Medical Oncology And Haematology, Kantonsspital St. Gallen, CH-9007 - St. Gallen/CH
  • 4Medical Oncology, Claraspital, 4058 - Basel/CH
  • 5Medical Oncology And Heamatology, Kantonsspital St. Gallen, 9007 - St. Gallen/CH

Abstract

Aim

Data regarding the role of PET-CT in patients with colorectal cancer (CRC) are sparse. Patients with pN2 CRC are at high risk of early relapse. Our institutional guidelines recommend PET-CT in these patients prior to adjuvant treatment to detect occult metastatic disease. The main objective of the present study was to assess the proportion of pN2 CRC patients, in which PET-CT detected metastases.

Methods

In the present single centre cohort study pN2 cM0 CRC patients deemed fit for adjuvant chemotherapy and without evidence of metastatic disease on preoperative CT scans were included. All PET-CT findings were either confirmed by biopsy or unequivocal clinical course.

Results

50 pN2 cM0 CRC patients (20 female, 30 male) were included from July 2007 to March 2014. Median age was 63 years (range: 37–78), median number of resected lymph nodes was 19 (range: 7–50), median number of metastatic lymph nodes was 8 (range: 4–18). New evidence of early recurrence or metastatic lesions was found in 8 patients (16%; 95%CI 7.2% - 29.1%), resulting in a number needed to screen of 6.25. Three of 8 PET-CT positive patients had oligo-metastatic disease potentially amenable for complete resection. CEA was normal in 4 of 8 PET-CT positive patients. Right-sided primaries seemed to show a tendency for higher rate of early PET-CT positive relapse (38% vs. 12%, P = 0.10). Age, number of resected lymph nodes or metastatic lymph nodes were not significantly different between PET-CT positive and negative patients (all P > 0.05).

Conclusions

This is the first analysis to evaluate the role of PET-CT in pN2 CRC patients. Our investigation demonstrates that previous occult disease prior to pre-planned adjuvant chemotherapy can be found in about 1 out of 6 patients resulting in a low number needed to screen in this high risk CRC group. Postoperative CEA levels were normal in half of these patients and thus cannot replace PET-CT. Integrating PET-CT findings in addition to routine staging procedures had a relevant impact in treatment decisions in our cohort of pN2 CRC patients. Further evaluation of PET-CT in larger cohorts is warranted.

Disclosure

All authors have declared no conflicts of interest.