Quality of treatment and surgical approach for rectal gastrointestinal
stromal tumour (GIST) in a large European cohort
Nikki S. IJzerman
a
,
b
,
*
, Mahmoud Mohammadi
c
, Dimitri Tzanis
d
,
2
, Hans Gelderblom
c
,
Marco Fiore
e
, Elena Fumagalli
f
, Piotr Rutkowski
g
, Elzbieta Bylina
g
, Ioannis Zavrakidis
h
,
Neeltje Steeghs
a
, Han J. Bonenkamp
i
, Boudewijn van Etten
j
, Dirk J. Grünhagen
k
,
Shahnawaz Rasheed
l
, Paris Tekkis
l
, Charles Honor
e
m
,
2
, Winan van Houdt
n
,
Jos van der Hage
o
, Sylvie Bonvalot
d
,
2
, Yvonne Schrage
p
,
1
, Myles Smith
n
,
1
a
Sarcoma Unit, Department of Medical Oncology, Netherlands Cancer Institute, Amsterdam, the Netherlands
b
Department of Medical Oncology, Erasmus MC Cancer Institute, Erasmus University Medical Center, Rotterdam, the Netherlands
c
Leiden University Medical Center, Department of Medical Oncology, Leiden, the Netherlands
d
Department of Surgery, Institut Curie, PSL University, Paris, France
2
e
Fondazione IRCCS Istituto Nazionale dei Tumori, Department of Surgery, Milano, Italy
f
Fondazione IRCCS Istituto Nazionale dei Tumori, Department of Medical Oncology, Milano, Italy
g
Maria Sklodowska-Curie National Research Institute of Oncology, Department of Soft Tissue/Bone Sarcoma and Melanoma, Warsaw, Poland
h
Netherlands Cancer Institute - Antoni van Leeuwenhoek, Department of Epidemiology and Biostatistics, Amsterdam, the Netherlands
i
Radboud University Medical Centre, Department of Surgical Oncology, Nijmegen, the Netherlands
j
University of Groningen, University Medical Centre Groningen, Department of Surgery, Groningen, the Netherlands
k
Erasmus MC e Cancer Institute, Department of Surgical Oncology, Rotterdam, the Netherlands
l
Sarcoma Unit, Department of Surgical Oncology, Royal Marsden Hospital, London, UK
m
Gustave Roussy, Surgical Oncology department, France
2
n
Netherlands Cancer Institute - Antoni van Leeuwenhoek, Department of Surgical Oncology, Amsterdam, the Netherlands
o
Leiden University Medical Center, Department of Surgery, Leiden, the Netherlands
p
Netherlands Cancer Institute - Antoni van Leeuwenhoek, Department of Surgical Oncology, the Netherlands and European School of Soft Tissue Sarcoma
Surgery, Amsterdam, the Netherlands
article info
Article history:
Received 14 January 2020
Accepted 20 February 2020
Available online xxx
Keywords:
Gastrointestinal stromal tumours
Rectum
Surgery
Treatment outcome
Survival
abstract
Background: Rectal gastrointestinal stromal tumours (GISTs) are rare tumours. Variability in the man-
agement may influence outcome, but there is a lack of understanding regarding contemporary variance
in care. A multicenter, international, retrospective cohort study was performed to elucidate character-
istics and outc omes of rectal GIST in European practice, with particular reference to surgical approach.
Methods: All rectal GIST patien ts diagnosed between 2009 and 2018 were identified from five European
databases. Recurrence free survival (RFS) and overall survival (OS) were estimated using Kaplan-Meier
method. Possible confounders were identified using Cox regression analyses.
Results: From 210 patients, 155 patients had surgery. The three main types of surgery were local tumour
resection (LTR, n ¼ 46), low anterior resection (LAR, n ¼ 31) and abdomino-perineal resection (APR,
n ¼ 32). Most patients received neoadjuvant (65%) and/or adjuvant imatinib therapy (66%). Local
recurrence rate after surgery was 15% and overall recurrence rate 28%. No signi ficant differences were
found in terms of RFS nor OS between LTR, LAR and APR. However, locally resected tumours were
smaller, while LAR and APR patients more often received perioperative imatinib. General hospitals
treated smaller GISTs, offered imatinib less frequently, and had a higher tumour rupture rate. In the
* Corresponding author. Netherlands Cancer Institute, Department of Medical Oncology, Plesmanlaan 121, 1066, CX, Amsterdam, Netherlands.
E-mail addresses: n.ijzerman@nki.nl (N.S. IJzerman), m.mohammadi@lumc.nl (M. Mohammadi), dimitri.tzanis@curie.fr (D. Tzanis), a.j.gelderblom@lumc.nl
(H. Gelderblom), marco.fiore@istitutotumori.mi.it (M. Fiore), elena.fumagalli@istitutotumori.mi.it (E. Fumagalli), piotr.rutkowski@coi.pl (P. Rutkowski), elab@coi.waw.pl
(E. Bylina), izavrakidis@mail.com (I. Zavrakidis), n.steeghs@nki.nl (N. Steeghs), han.bonenkamp@radboudumc.nl (H.J. Bonenkamp), b.van.etten@umcg.nl (B. van Etten), d.
grunhagen@erasmusmc.nl (D.J. Grünhagen), Shahnawaz.rasheed@rmh.nhs.uk (S. Rasheed), paris.tekkis@rmh.nhs.uk (P. Tekkis), charles.honore@gustaveroussy.fr
(C. Honor
e), w.v.houdt@nki.nl (W. van Houdt), j.a.van_der_hage@lumc.nl (J. van der Hage), sylvie.bonvalot@curie.fr (S. Bonvalot), y.schrage@nki.nl (Y. Schrage), Myles.
Smith@rmh.nhs.uk (M. Smith).
1
these authors share senior authorship.
2
on behalf of the French Sarcoma group.
Contents lists available at ScienceDirect
European Journal of Surgical Oncology
journal homepage: www.ejso.com
https://doi.org/10.1016/j.ejso.2020.02.033
0748-7983/© 2020 Elsevier Ltd, BASO ~ The Association for Cancer Surgery, and the European Society of Surgical Oncology. All rights reserved.
European Journal of Surgical Oncology xxx (xxxx) xxx
Please cite this article as: IJzerman NS et al., Quality of treatment and surgical approach for rectal gastrointestinal stromal tumour (GIST) in a
large European cohort, European Journal of Surgical Oncology, https://doi.org/10.1016/j.ejso.2020.02.033
multivariate analysis in the group having LTR, APR or LAR, the only significant prognostic factor for local
recurrence was higher age (HR 1.06, CI 1.00e1.12, p ¼ 0.048).
Conclusions: In European clinical practice for rectal GIST, LTR, LAR and APR have comparable local
control. Multimodal approach is higher and tumour rupture less frequent in specialist centres compared
to general hospitals.
© 2020 Elsevier Ltd, BASO ~ The Association for Cancer Surgery, and the European Society of Surgical
Oncology. All rights reserved.
1. Introduction
Gastrointestinal stromal tumours (GISTs) are rare tumours
arising from the mesenchymal tissue in the gastrointestinal tract
with an estimated incidence of 10e15 per million per year[1].
Approximately 5% of the GISTs occur in the rectum[2e5]. Variability
in the management of this rare tumour may influence outcome, but
there is a lack of understanding regarding contemporary variance
in care. Due to the rarity of GIST, a multidisciplinary approach with
the involvement of centres with relevant expertise has been
recognized as an important factor[6]. There is however limited
evidence-based data regarding the treatment of rectal GIST. Most
published studies are either single centre experiences with limited
number of patients[7e12] or series lacking detailed data about
important prognostic factors[13,14], which makes it difficult to
interpret the data and limits the clinical application.
Furthermore, since GISTs located in the rectum has been
described as an adverse prognostic factor[15], the European Society
of Medical Oncology (ESMO) guidelines state that surgical resection
should be considered in all rectal GIST patients, irrespectively of
tumour size[6]. Furthermore, MRI is advised as primary imaging
modality. However, specific surgical strategies are not discussed
within ESMO guidelines. Consideration of the surgical approach, is
important due to the technically challenging nature of rectal GIST,
relating to the precise site of origin in the rectum, its relation to the
sphincter complex, the risk of tumour rupture and positive mar-
gins, and the relationship to vital structures in the pelvic cavity. The
decision about the approach and extent of surgery is therefore
crucial for achieving histologically negative margins and at the
same time it should be balanced according both to oncological risk
and functional morbidity. Other considerations in this group of
patients are related to the mode of biopsy, the influence and timing
of neoadjuvant treatment on mode of surgery and oncological
outcomes, and whether there is benefit in being managed in a high-
volume specialist centre.
To address some of these questions, we present a multicentre,
international retrospective study including patients with rectal
GIST from five European countries, which represents one of the
largest series in rectal GIST. The primary aim of this study is to
elucidate the characteristics of rectal GIST and outcome of different
treatment modalities in contemporary European practice.
2. Methods
2.1. Study design and patient selection
This is a retrospective, multicenter, international cohort study.
We adhered to the STROBE guidelines for cohort studies. Data from
five different GIST databases were combined to achieve an
adequate sample size. All patients diagnosed with rectal GIST be-
tween January 2009 and January 2018 were selected to prevent any
type of selection bias. Participating countries were the Netherlands
(Dutch GIST consortium, sites: UMC Groningen, Netherlands Cancer
Institute, Leiden UMC, Erasmus MC, Radboud MC), Italy (site:
Fondazione IRCSS Istituto Nazionale dei Tumori Milano), France
(French Sarcoma Group, sites: NetSarc centres), UK (site: the Royal
Marsden Hospital) and Poland (site: Maria Sklodowska-Curie Na-
tional Research Institute of Oncology). Patients were excluded from
the analysis when essential information was missing, being gender
and whether patients underwent surgery.
2.2. Main outcome measures
The primary endpoint was to describe the outcomes of rectal
GIST in European practice, in terms of local recurrence rate, recur-
rence free survival (RFS) and disease specific survival (DSS). Sec-
ondary descriptive endpoints were tumour characteristics (i.e. size,
mitotic count, mutational status, baseline distance to anal verge),
the impact of neoadjuvant and adjuvant imatinib therapy (i.e. time
to maximal tumour reduction, change in size and mitotic count,
percentage of post-treatment viable cells), number of patients with
radiotherapy and surgery characteristics (i.e. type of surgery, severe
complications classified by at least grade 3b according to Clavien-
Dindo classification, margins, peroperative tumour rupture).
2.3. Surgical procedures
Local tumour resection (LTR) includes transanal excision,
transanal endoscopic microsurgery and transperineal approach for
resection of the anal canal. Two other common surgical procedures
were low anterior resection (LAR) and abdomino-perineal resection
(APR).
2.4. Statistical analyses
Statistical analyses were performed using IBM SPSS Statistics 25.
Time to maximum reduction of tumour size on neoadjuvant ima-
tinib treatment was calculated from start date until the date of the
maximum achieved radiological reduction. Survival estimates were
obtained using the Kaplan-Meier method and compared by log-
rank test. RFS was calculated from date of surgery to date of
recurrence or date of last follow-up. DSS was calculated from the
date of diagnosis to date of death or date of last follow-up. Potential
confounders were identified by using univariate Cox regression
analysis. Only confounders with a p-value below 0.3 were subse-
quently included in the multivariate analysis. All tests were two-
sided and a p-value of <0.05 was considered significant. In the
group with the three main types of surgery, multiple imputation
(Predictive Mean Matching, 20 times, 50 iterations) was performed
in SPSS for missing values of likely confounders.
3. Results
3.1. Patient characteristics
In total, 231 patients with rectal GIST were identified from the
databases. After exclusion of 21 patients due missing essential in-
formation, 210 patients were ultimately included: 48 patients from
N.S. IJzerman et al. / European Journal of Surgical Oncology xxx (xxxx) xxx2
Please cite this article as: IJzerman NS et al., Quality of treatment and surgical approach for rectal gastrointestinal stromal tumour (GIST) in a
large European cohort, European Journal of Surgical Oncology, https://doi.org/10.1016/j.ejso.2020.02.033
the Netherlands, 35 from Italy, 22 from the UK, 36 from Poland and
69 from France.
Median age in these 210 patients was 61 years with 63% being
male (Table A1). Median tumour size at diagnosis was 65 mm and
median baseline distance to anal verge 34 mm. Three most com-
mon reported symptoms at diagnosis were rectal mass, rectal
bleeding and change in bowel habit. Mutation status was known for
156 patients (74%). Most of the GISTs were KIT exon 11 mutated
(71%), but also mutations in KIT exon 9 (14%), KIT exon 13 (3%),
PDGFR (n ¼ 1) and KIT/PDGFR wildtype (12%) were reported. Mitotic
rate at baseline was low (5/50 HPF) in 59% and high (>5/50 HPF)
in 41% of the patients.
In this cohort, 55 patients did not undergo surgery (Fig. A1). The
main reason for this was metastatic disease, other reasons were
unfitness for surgery, patients declining surgery and ongoing
response on systemic treatment. From the surgeries, LTR was most
often performed, followed by APR and LAR.
3.2. Main types of surgery
The group with the three main types of surgeries (LTR, LAR and
APR) consists of 109 patients (Table A2). None of these patients had
metastatic disease at diagnosis. Median age in this group was 61
years and 70% were male. Median baseline tumour size was 61 mm
and median distance to the anal verge 35 mm. In one patient, the
tumour extended into the sphincter and in 4 patients it was 1cm
from the sphincter. Most GISTs were KIT exon 11 mutated (74%).
Comparing the three groups of surgery, smaller tumours more often
had LTR. No significant differences were found in baseline mitotic
rate, peroperative tumour rupture and resection margins. The severe
complication rate was low (4.4%). Patients with a LAR or APR
received neoadjuvant imatinib therapy more frequently compared to
the LTR group (77% or 91% vs. 54% resp.), but this difference was not
noticed in the adjuvant treated group (86% or 61% vs. 61% resp.,
p ¼ 0.062). When comparing LAR with APR separately, patients with
a LAR received adjuvant imatinib more often than patients having an
APR (86% vs. 61%). No other differences were found in characteristics
between patients with a LAR and APR.
3.3. Location of surgery: general hospital versus specialist centre
For 140 patients that had surgery (90%) the type of hospital was
specified. Fifty-one (36%) operations were performed in a general
hospital not specialized in GIST surgery. These operations were
mainly LTRs and baseline tumour size was smaller (median 44 mm
vs. median 67 mm, p ¼ 0.002). Patients that had surgery in general
hospitals were less often treated with neoadjuvant and adjuvant
imatinib (13% vs. 96% (p < 0.001) and 51% vs. 72% (p ¼ 0.026) resp.).
No difference was found in resection margins (p ¼ 0.131), but
peroperative tumour rupture was more often reported in general
hospitals compared to specialized centres (37% vs. 5%, p < 0.001).
Local RFS was significantly shorter for all patients with peroper-
ative tumour rupture (n ¼ 17) in univariate KM analysis (p < 0.001,
median not reached), but this effect was lost in multivariate Cox
regression analysis. Furthermore, no statistically signifi
cant differ-
ence was detected for local RFS between patients that underwent
surgery in a general hospital or specialist centre (p ¼ 0.240, median
not reached).
3.4. (Neo)adjuvant treatment
In the surgery cohort, most of the patients received neoadjuvant
(65%) and/or adjuvant therapy (66%). Neoadjuvant therapy was
imatinib 400 mg QD in 91% of the cases, and few received imatinib
800 mg QD (n ¼ 7, mostly KIT exon 9 mutated) or masitinib or
sunitinib if there was severe imatinib toxicity (n ¼ 2 and n ¼ 1
resp.). Median time on neoadjuvant treatment was 10 months
(range 1e102), whereas the time to maximum tumour reduction,
reviewed retrospectively and available for only 45% of patients, was
6 months (median, range 2e38). Patients treated with neoadjuvant
imatinib had a median size reduction of 33% (range 100 to 20%,
available for 86% of the patients) and a decrease in mitotic count of
2.5 (median, range 39 to 11, only available for 36% of the patients).
The median percentage of viable cells after neoadjuvant therapy
was 30% (0e100, available for 51% of the patients). Median time on
adjuvant imatinib treatment was 25 months (range 0e112). In the
whole cohort at least 12 patients received radiotherapy. Four pa-
tients were treated with radiotherapy adjuvant because of high risk
features and, remarkably, only one of them had a recurrence.
3.5. Outcome in general
Median follow-up time after surgery was 28 months (range
0e115). During this follow-up time 43 patients had a recurrence
(recurrence rate 28%): 17 patients a local recurrence (recurrence
rate 11%), 19 patients had distant recurrent disease only (recurrence
rate 12%) and 7 patients had simultaneously local and distant
recurrent disease (recurrence rate 5%). Median all RFS was 75
months (95% confidence interval (CI) of 64e85 months). Median
local RFS was not reached. Overall 12 patients died from which 10
died of disease (5%), but most of them did not have surgery: only 3
patients that underwent surgery died of disease (2%). There was no
difference in DSS (p ¼ 0.644) comparing the three main types of
surgery.
3.6. Prognostic factors for a local recurrence within the group with
three main surgeries
Using the Kaplan Meier method, local RFS did not differ between
the three main surgeries (Fig. A2). No difference in local RFS was
found comparing the country of surgery (p ¼ 0.348). Furthermore,
local RFS was not significantly longer after adjuvant imatinib
(p ¼ 0.848) nor neoadjuvant imatinib (p ¼ 0.186). No difference in
local RFS was found comparing high risk rectal GIST (size >5 cm,
mitotic count >5 and/or peroperative tumour rupture) with low
risk rectal GIST (p ¼ 0.283).
Cases with missing data were automatically excluded from the
Cox regression analysis. To make the results more reliable, multiple
imputation of the missing data was done for the expected possible
confounders within the group of three main surgeries (percentage
missing data: baseline mitotic rate 42%, distance to anal verge 25%,
peroperative tumour rupture 21%, severe complications 17% and
mutation status 16%). After multiple imputation, Cox regression
analysis was performed (Table A3). Using the p-value threshold of
0.3, older age, larger baseline tumour size, closer to anal verge,
positive resection margin, peroperative tumour rupture and no
neoadjuvant imatinib were associated with worse local RFS on
univariate Cox regression analysis. In multivariate analysis, using a
p-value threshold of 0.05, the only significant prognostic factor for
local recurrence was older age (HR 1.057, CI 1.000e1.116, p ¼ 0.048).
4. Discussion
In this retrospective cohort study, the characteristics of rectal
GIST in European practice were investigated. The average rectal
GIST patient in this series is 61 years old and male (63%), presenting
most commonly with a rectal mass, rectal bleeding or a change in
bowel habits. The vast majority has a resection of the primary
tumour, being most frequently a LTR, LAR or APR. The recurrence
rate after surgery was high, despite the majority of patients having
N.S. IJzerman et al. / European Journal of Surgical Oncology xxx (xxxx) xxx 3
Please cite this article as: IJzerman NS et al., Quality of treatment and surgical approach for rectal gastrointestinal stromal tumour (GIST) in a
large European cohort, European Journal of Surgical Oncology, https://doi.org/10.1016/j.ejso.2020.02.033
perioperative treatment with imatinib. Smaller tumours were most
likely treated by LTR, while LAR and APR patients received more
often perioperative imatinib therapy. LTR, LAR and APR appear to
have comparable oncological outcome.
Several European studies relating to rectal GIST have been
published [7e10], all focusing on differences in outcome after
surgery with and without neoadjuvant imatinib, but these studies
suffer from small sample sizes and may not reflect contemporary
practice. Two recent studies were performed with a larger sample
size, but are limited by lack of detailed data about important
prognostic factors, tumour size prior to pre-operative therapy and
recurrence rate [14,16]. Our cohort has the benefit of having a larger
sample size, representing multiple institutions, with a wide range
of variables that may help inform practice.
Contrary to expectations, in our cohort, tumour rupture and
negative resection margins did not appear to influence the risk for
recurrence in multivariate analysis. A possible explanation could be
a protective effect of perioperative imatinib, but this did not appear
to reduce the risk for local recurrence in multivariate analyses
either. That may be related both to selection bias in treating pa-
tients at higher risk with imatinib and to the relatively low number
of events.
The median time of maximum tumour reduction on neo-
adjuvant imatinib in our series was 6 months. This duration is in
line with the time to maximum tumour reduction of 6.9 months
found by Wang et al. in 17 rectal GIST patients[17]. Despite the
dogma that optimal neoadjuvant imatinib therapy takes longer in
rectal GIST patients, the duration of treatment to maximal tumour
regression seems comparable to other GIST locations[18,19].
Furthermore, the range of optimal response time is wide and
frequent scans to evaluate response should be scheduled.
In this cohort, twelve patients had radiotherapy. Due to the
overall good response rates to imatinib, reliable data about the
influence of radiotherapy is scarce[6]. In recent years however,
several studies were performed regarding radiotherapy in GIST.
Joensuu et al. investigated radiotherapy in 25 metastatic GIST pa-
tients, whereof 19 patients were concomitantly treated with tyro-
sine kinase inhibitors. Responses to radiotherapy were infrequent
(8%), but most patients had durable stabilization (80%) despite
confounding from TKI treatment is likely[20]. Some other series
show promising results in specific scenarios, but more studies are
needed to determine the specificinfluence of radiotherapy on
oncological outcome[21e23]. However, radiotherapy can be
considered among possible therapeutic options in patients who do
not want surgery and wish to stop or are progressive on TKIs.
Consideration should be given to the type of institution initial
surgery was performed, and if there is any potential influence on
outcomes. We observed that despite the smaller tumour size in
general hospitals, the frequency of tumour rupture was higher in
general hospitals compared to specialist centres. This suggests that
the quality of surgery was superior in specialist centres: despite
smaller cancers and less extensive surgery, there was a higher rate
of tumour rupture in general hospitals. Moreover, patients had
lower chance to be offered multimodal treatment in general hos-
pitals. Nevertheless, the oncological outcome was not different in
general hospitals, which might be explained by selection bias
where the high risk tumours are referred to specialized centres.
These findings highlight the importance of management of rectal
GISTs in specialist centres. The overall rarity of rectal GIST de-
termines that they are very unfamiliar in routine clinical care.
Management is frequently complex and pathways of care are
complicated, which can be overcome by specialized multidisci-
plinary GIST care. Moreover, another advantage of centralized care
is that more patients can be included in studies which will ulti-
mately ensure improved care.
Of interest was that a substantial proportion of patients declined
surgery when indicated. Declining end stomas and concerns
regarding and the impact of surgery on quality of life were identi-
fied as the most common underlying motivations. This demon-
strates the importance of shared decision making with patients and
personalized surgery for patients with rectal GIST, in particular
with the availability of alternative treatments to surgical resection.
The ESMO guideline recommends MRI as pre-operative imaging
in rectal GIST. However, when collecting the data, we noticed that
in the Netherlands quite often CT scans were done instead, prob-
ably due to limited capacity. In contrast, standard MRI scanning is
done in the UK. Another interesting observation was that, addi-
tionally to MRI scanning, an examination under anesthesia
including rigid sigmoidoscope digital rectal examination is per-
formed pre-operatively in the RMH for optimal surgical planning. It
would be interesting to determine the influence of these different
ways of pre-operative tumour assessment on oncological outcome
and choice of surgical approach in future research.
The main limitation of our study is the relatively short follow-up
time compared to the median RFS (28 months vs. 75 months). The
number of events is therefore low and definite conclusions can only
be drawn after analysis of data with longer follow-up. Another
problem is the amount of missing data in certain variables, which
was addressed by using imputation. Furthermore, it would have
been informative to ascertain what proportion of patients initially
thought to require an APR, but ultimately had a sphincter sparing
procedure after neoadjuvant treatment with imatinib. Neverthe-
less, this is the largest cohort of European rectal GIST patients to
date, and one of the largest in the literature, and it is illustrative to
combine all available data on such a rare tumour from countries
that all manage patients according to the ESMO guideline.
5. Conclusions
This study represents a large cohort of surgically treated rectal
GIST patients in Europe. In European clinical practice, smaller tu-
mours are most likely treated by LTR, while the larger tumours are
preferentially treated with LAR and APR and patients receive more
often perioperative imatinib therapy. LTR, LAR and APR have
comparable oncological outcome. Quality of treatment (multi-
modal approach, less peroperative tumour rupture) appears to be
superior in specialist centres and referral of rectal GIST to specialist
centres is therefore recommended.
Funding
A research grant for the Dutch GIST Registry was received from
Novartis (3017/13), Pfizer (WI189378) and Bayer (2013-MED-
12005). These funding sources did not have any involvement in
conducting this research.
Declaration of competing interest
P. Rutkowski has received honoraria for lectures and Advisory
Board from Novartis, Pfizer and Blueprint Medicines. The other
authors declare that they have no known competing financial in-
terests or personal relationships that could have appeared to in-
fluence the work reported in this paper.
Appendix
N.S. IJzerman et al. / European Journal of Surgical Oncology xxx (xxxx) xxx4
Please cite this article as: IJzerman NS et al., Quality of treatment and surgical approach for rectal gastrointestinal stromal tumour (GIST) in a
large European cohort, European Journal of Surgical Oncology, https://doi.org/10.1016/j.ejso.2020.02.033
Table A1
Patient and tumour characteristics whole cohort of GIST patients.
Characteristic No. %
210 100
Gender
Male 132 63
Female 78 37
Age (median, range) 61 (18e91)
Tumour size at diagnosis in mm (median, range) 65 (3e250)
Distance to anal verge in mm (median, range) 34 (0e200)
Most important symptom at diagnosis
Rectal bleeding 27 13
Change in bowel habits 25 12
Rectal mass 22 11
Pain 16 8
Urinary tract problems 94
Incidental finding 94
Screening program 21
Vaginal bleeding 21
Not specified 22 11
Mutation status
KIT exon 11 110 53
KIT exon 9 21 10
Wildtype (KIT/PDGFR) 19 9
KIT exon 13 52
PDGFR 11
Mitotic rate at baseline
Low (5/50 HPF) 63 59
High (>5//50 HPF) 43 41
Surgery yes/no
Yes 155 74
No 55 26
Fig. A1. Flowchart of rectal GIST patients.
N.S. IJzerman et al. / European Journal of Surgical Oncology xxx (xxxx) xxx 5
Please cite this article as: IJzerman NS et al., Quality of treatment and surgical approach for rectal gastrointestinal stromal tumour (GIST) in a
large European cohort, European Journal of Surgical Oncology, https://doi.org/10.1016/j.ejso.2020.02.033