FMISO PET & perfusion CT at baseline and; week 2 CRT as predictive markers for response in rectal cancer

T. Greenhalgh, J. Wilson, Tanuj Puri, J. Franklin, L. Wang, R Goldin, K. Chu, V. Strauss, M. Partridge, T. Maughan

Research output: Contribution to journalArticlepeer-review


Purpose or Objective: Patients with locally advanced rectal cancer are
considered for neoadjuvant CRT. Around 15% have a
complete response with a similar proportion having
minimal response. This study explores the predictive value
of FMISO-PET and perfusion CT (pCT).
Material and Methods: Patients having neoadjuvant CRT for rectal cancer were
recruited at a single centre from October 2013-April 2016.
FMISO-PET and pCT were done at baseline and in week 2
CRT. Tumour was delineated on MRI by a radiologist,
copied to CT using rigid registration and amended for air.
FMISO SUVmax in tumour (T) and muscle (M), and
perfusion parameters Blood Volume (BV) and Blood Flow
(BF) were determined. Pathological tumour regression
grade was scored by AJCC 7.0.
Results: 11 patients were recruited with median age 67
(interquartile range (IQR) 19). 9(82%) were male. Staging
was T2 in 2 (18%) and T3 in 9 (92%). 4 (36%) were node
negative, 6 (55%) N1 and 1 (9%) N2. All had M0 disease. 7
patients had total mesorectal excision. 7 patients were
classed as good responders (AJCC 0/1 or good clinical
response) and 4 as poor responders (AJCC 2/3 or poor
clinical response). FMISO scans were evaluable in 8/10 patients at baseline
and in 8/9 at week 2 CRT (Table 1). Reasons for
unevaluability were non-tumour uptake either in the
colorectal lumen, which was maximal on the 4 hour scan
due to colonic excretion of FMISO, or through spill in from
adjacent bladder activity. Using a threshold of T:M
SUVmax ratio of > 1.3, a hypoxic tumour volume was
identified at baseline in 7/8 and in 5/8 at week 2 CRT.
Baseline median T:M SUVmax was 3.1 (interquartile range
(IQR) 1.3). In 5/7 patients with paired evaluable scans, the
T:M ratio reduced (≥25% reduction in SUV max), however
this showed no correlation with outcome in this small
dataset. All patients had evaluable pCT at baseline and week 2
CRT. Neither baseline median BV (3.2, IQR 2.1) nor BF
(23.2, IQR 18) showed a relationship with response. There
was also no clear trend for change at week 2 CRT in
median BV (2.8, IQR 2.2)) or BF (21, IQR 38.3)). An
example FMISO-PET/CT and BV pCT map at baseline and
week 2 CRT is shown in Figure 1. Conclusion
This pilot study revealed significant challenges in delivery
and interpretation of FMISO PET scanning for rectal
cancer. Preliminary data does not support the hypothesis
that a reduction in FMISO uptake is predictive of response.
In addition, no association was seen between pCT
parameters and response; larger scale studies would be
required to establish the value of this functional imaging
Original languageEnglish
Article numberEP-1278
Pages (from-to)S686–S687
Number of pages2
JournalRadiotherapy and Oncology
Issue number1
Publication statusPublished - 1 May 2017

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  • Manchester Cancer Research Centre


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