Review Article
Low Anterior Resection Syndrome: Description, Measurement, Risk Factors
Celia Keane1 and Ian Bissett1,2*
1Department of Surgery, University of Auckland, New Zealand
2Department of Surgery, Auckland City Hospital, New Zealand
*Corresponding author: Ian P. Bissett, Department of Surgery, University of Auckland, Private Bag 92019 Auckland Mail Centre 1142, New Zealand
Published: 05 Dec, 2016
Cite this article as: Keane C, Bissett I. Low Anterior
Resection Syndrome: Description,
Measurement, Risk Factors. Clin Surg.
2016; 1: 1194.
Abstract
Low anterior resection syndrome (LARS) is increasingly recognized as a concern after low
anterior resection for the treatment of rectal cancer. The lack of a precise definition outlining the
symptoms and the time course that constitute LARS hinders ongoing research into the incidence,
risk factors, pathophysiology, and treatment of this syndrome. This review will outline the current
characterization of LARS, the approach to measuring LARS, and the risk factors for development
of LARS. It will highlight the significant heterogeneity in the literature to date and the limitations in
our understanding of LARS.
Keywords: Low anterior resection syndrome (LARS); Abdominoperineal resection (APR); Anterior resection syndrome (ARS)
Introduction
Miles described the abdominoperineal resection (APR) in 1908 [1] and it remained the gold
standard for the treatment of rectal cancer until the introduction of the anterior resection procedure
in 1948 [2]. The requirement for a 5cm distal resection margin initially limited anterior resection
surgery to tumours in the upper and mid rectum [3]. In the 1980s the “5 cm rule” was challenged
when multiple studies found that a 5 cm distal resection margin had little effect on the oncological
outcome and the circumferential resection margin (CRM) was identified as the key to reducing
local recurrence [4-7]. During the same period, Heald and colleagues emphasized strict adherence
to anatomical planes of dissection and introduced total mesorectal excision (TME) [8]. Using this
principle they achieved a local recurrence rate of 8% [9] in an era when the local recurrence rate
was 20% to 40% [3,10]. These advances meant that distal colorectal and even coloanal anastomoses
were theoretically possible [7]. The advent of circular stapling devices made the creation of these
anastomoses easier, quicker, and safer [3,11].
Until the 1980s improvements in the treatment of distal rectal cancer were focused on
improving mortality, survival, and local recurrence. The advances in the 1980s allowed another
goal to emerge - preserving continence. During the 1980s and1990s, attempts to improve functional
outcome after sphincter preserving surgery resulted in the introduction of different reconstruction
techniques including the colonic J pouch and the transverse coloplasty [12-14]. Stoma avoidance was
challenged as the most important determinant of quality of life after distal rectal cancer resection
as the explosion of literature examining functional outcomes highlighted how common defaecatory
dysfunction was after low anterior resection [15-18].
Clinical Characteristics of LARS
An anterior resection involves removal of the rectum and restoration of bowel continuity
by creating an anastomosis between the colon and the rectal remnant or the anal canal [19].
Unsurprisingly, the removal of the rectum with its associated storage capacity and specialized
sensory and motor function results in a change in bowel function [20]. Anterior resection syndrome
(ARS) or low anterior resection syndrome (LARS) describes the dysfunction experienced after a
sphincter-preserving rectal cancer resection. LARS is common and has been reported in 10% to
90% of patient’s post-rectal resection [20-22]. Substantial heterogeneity in the functional outcomes
reported after low anterior resection makes it impossible to pool the data and to draw externally valid
conclusions regarding LARS [23]. This prompted Bryant and her colleagues to propose a pragmatic
definition of (L) ARS: “disordered bowel function after rectal resection, leading to a detriment in
quality of life” [20]. This definition captures the major features of LARS but it lacks specificity.
A consensus definition that specifies the symptoms and time frame
required to constitute LARS, is needed to enable standardized
research to advance the understanding of the incidence, risk factors,
pathophysiology, and treatment of this syndrome.
LARS is used to describe a variety of symptoms. The bowel
dysfunction may be categorized into storage dysfunction, which
includes bowel frequency, faecal urgency and incontinence, and
evacuatory dysfunction, which includes stool fragmentation or
clustering [20,22,24,25]. Gas-stool discrimination, tenesmus, anal
pain, passage of blood or mucus per anus have also been reported
within the construct of LARS [24]. Some researchers also include
urinary and sexual dysfunction within LARS, but these features will
not be addressed in this review [24]. Frequency is usually reported
as the number of bowel motions over a 24-hour period but may be
differentiated into diurnal and nocturnal bowel frequency [26].
Reports of faecal incontinence may include the presence or severity
of flatus, liquid, or solid stool incontinence, mucus discharge,
and diurnal or nocturnal incontinence [26]. Patients may also
be questioned about pad usage [26]. Faecal urgency is usually
measured by asking patients if they have an urgent need to pass a
bowel motion with the implication that incontinence would result
if they were unable to reach the toilet. Deferral time, the length of
time that the passage of stool can be deferred following the onset of
the urge to evacuate, may also be used to assess urgency [26]. Bowel
fragmentation or ‘clustering’ refers to the need to pass multiple
bowel motions within a defined period of time, most often 1 hour
[22,26]. Evacuatory dysfunction may include constipation, a sense
of incomplete evacuation or of residual stool, inability to evacuate
the bowel within a certain amount of time, use of evacuatory aids,
or straining [26]. The ability to differentiate between gas and stool
or to ‘safely release flatus’ is often measured as a marker of impaired
anorectal sensation [26].
Lack of consensus on the symptoms that constitute LARS has lead
to heterogeneous reporting of symptoms deemed to be significant
by individual research groups. Scheer and colleagues reviewed the
literature and found 48 papers that reported functional outcome
after anterior resection [27]. They calculated the frequency that each
symptom was reported and showed that there was significant variation
in outcome measures reported between studies [27]. However
all studies included in their meta-analysis evaluated urgency and
incontinence (of some kind) [27]. Over half of the studies measured
pad usage (86%), incontinence of liquids (58%), solids (53%), or gas
(53%), clustering (53%), and inability to differentiate gas from stool
(53%) [27]. Incomplete evacuation and increased frequency (four or
more bowel motions per day) were assessed in 35% of studies and
nocturnal bowel motions were assessed in 12% of studies [27].
Bryant’s definition suggests that the impact of post-operative
bowel dysfunction on quality of life is inherent within concept of
LARS [20]. The impact on quality of life may be assessed within the
construct of LARS or may be assessed separately using validated
quality of life tools, such as the European Organization for Research
and Treatment of Cancer (EORTC)modules (QLQ-C30, -CR38
or -CR29) [26]. Both approaches have been used but some experts
argue that it is conceptually flawed to measure bowel function using
instruments designed to measure quality of life [23,26]. Behaviors
such as pad use, dietary modifications, toilet dependence, and social
isolation have been reported and show that the bowel dysfunction
associated with LARS impacts on lifestyle and quality of life.
Dissatisfaction with bowel function and affect on overall well being
have also been used to measure this feature of LARS [26]. Another,
possibly more appropriate method of measuring the impact of
bowel dysfunction on quality of life, is by using an instrument that
incorporates symptoms shown to impact on quality of life, such as
the LARS score [26].
Perhaps the greatest inconsistency in reporting of outcome is the
length of the follow-up period. Bowel dysfunction immediately after
rectal resection is expected, but there is no consensus regarding the
time frame that constitutes pathological dysfunction after resection.
Lack of a standardized post-operative time period has lead to a wide
range in the reported incidence of LARS. The authors are not aware
of any proposed definition of LARS that incorporates a specified
time period. The two scores specifically developed to measure bowel
function following restorative rectal resection; the MSKCC BFI [29]
and the LARS score [28], were developed and validated using patients
who were at least 5 months and 2 years post-resection, respectively.
However, neither the authors nor any other groups have specified
the time point at which these instruments should be applied. These
specific LARS questionnaires should now be used to assess incidence
at various time points after restoration of bowel continuity to inform
discussion as to the time point at which the dysfunction could be
considered to constitute LARS. Once there is consensus over the time
period that constitutes LARS, further standardization will be possible
to allow for investigation into risk factors and treatments of LARS.
Measurement of LARS
Multiple instruments have been developed to measure functional
outcome after LAR but none are in widespread use, presumably
because they are not based on a robust definition of LARS [20].
The Colorectal Functional Outcome (COREFO) and the Hallbook
questionnaires measure post-operative bowel function including
incontinence, frequency, and social impact [30,31]. The COREFO
questionnaire also measures the need for medication, pain or
bleeding with bowel motions, and perianal skin irritation [30], while
the Hallbook questionnaire assesses abdominal pain [31]. Both
questionnaires have high reliability but the COREFO questionnaire
has greater criterion validity [30]. Two instruments specifically
developed to measure functional outcome after sphincter preserving
surgery are the Bowel Function Instrument (BFI) and the Low
Anterior Resection Syndrome (LARS) score. The bowel function
instrument was first published in 2005 and includes 18 questions
grouped into three subscales; frequency, dietary, urgency/soilage,
and four individual questions [29]. An overall score can be calculated
and transformed into an outcome category: excellent, good, fair, or
poor function [29]. In contrast to the comprehensive BFI, the LARS
score has been designed for quick, easy use in routine clinical practice
including follow-up consultations [28]. The LARS score consists of
five questions (Table 1) and can be used to generate an overall score
that translates into no LARS (score 0-20), minor LARS (21-29), major
LARS (30-42) [28]. The score for each question is weighted according
to its ccorrelation with the outcome of the following question
“Overall, how much does your bowel function affect your quality of
life?” [28] Patients suffering from major LARS report statistically and
clinically significant differences in quality of life compared to patients
with minor or no LARS [32]. Both the BFI and LARS score have
good reliability and validity [28,29]. The BFI has subsequently been
validated in a population of Italian patients [33]. The LARS score has
been validated in Chinese, English, Swedish, Spanish, German, and
Danish patient populations [34-36].
Frustratingly, studies investigating LARS employ a variety of
tools to assess functional outcome. A systematic review found that
65% of the included studies did not use a validated tool to measure
functional outcome after anterior resection for rectal cancer [27].
In these studies, most authors modified or developed their own
questionnaires to assess outcomes [27]. Faecal incontinence scores
have generally been relied upon when a validated tool is used to
measure functional outcome [23,27]. This may reflect availability or
author preference as clinicians have been shown to overemphasize
the importance of faecal incontinence [37]. Limiting the focus to
faecal incontinence overlooks symptoms such as clustering and
urgency, which have been shown to correlate with quality of life [28].
The measurement of functional outcomes after LAR is difficult
for many reasons. Patient-reported outcomes will be influenced by
cultural factors inherent in self-reporting, particularly when the
symptoms are embarrassing or stigmatized [26,38,39]. Patients may
want to avoid appearing ungrateful or may justify the poor functional
outcome as the price they paid to treat the cancer and save their lives
[39]. Over time, patients’ perception of the symptoms may change
as they adapt to a new level of functioning, particularly if they are
not aware of any treatment options [39]. It is essential for clinicians
to inquire about functional outcome, provide adequate explanations
to patients, and to identify patients who need treatment to improve
their symptoms [38]. It is also important to recognize that the
patients’ assessment of their functional outcome is the gold standard
[23]. To compare patients’ and specialists’ perspectives the authors
of the LARS score asked experts in the management of rectal cancer
to rank symptoms, then assign weighting to the symptoms based
on how disturbing each would be to the patient [37]. This novel
study illustrated that colorectal surgeons and radiation oncologists
underestimate the negative consequences of clustering and urgency
but overestimate the burden of incontinence and bowel frequency
compared to patient reports [37].
Risk Factors or Contributing Causes
Multiple factors have been implicated as contributors to
poor functional outcome after low anterior resection but lack of
standardization in the timing of assessment, outcome measures
assessed, and instruments used, have resulted in significant
inconsistencies in the literature. Without application of a consistent
definition of LARS it is very difficult to pool results and to draw
generalizable or externally valid conclusions. Much of the literature
reports faecal incontinence as the sole outcome of interest after rectal
resection so it is not possible to extrapolate the results to LARS [23].
Despite the heterogeneity, anastomotic height and radiotherapy have
repeatedly been associated with poor functional outcome after LAR
[40,41].
Anastomotic height
Anastomotic height is generally accepted to be the major
determinant of functional outcome after anterior resection but there
are some contradictory findings in the literature. Anastomotic height,
tumour height, and partial versus total mesorectal excision have all
been investigated as contributors to functional outcome. Although
these are interrelated as the level of the tumour will influence both
the anastomotic height and whether a partial (high rectal cancer) or
total mesorectal excision (mid or low rectal cancer) is performed,
they do not represent the same thing which may account for some
of the inconsistency in the literature. A retrospective study from
our unit found that level of anastomosis was a significant predictor
of ARS in the first two years (at 1year, LAR odds ratio (OR) 2.11,
ultra-LAR OR 4.34, at 2 years ultra-LAR OR 4.5) but this effect did
not persist beyond 2 years [42]. A prospective study conducted at
a median follow-up of 51 months found that both tumour distance
from the anal ring (>1 cm, OR 5.88) and anastomotic height (>2 cm
from anal verge, OR 6.59) were significant predictors of continence
using the Wexner score [43]. Another prospective study found that
tumour location (upper, middle, or lower rectum) was a significant
predictor of change in the BFI score at 1 year follow-up (compared to
pre-operative score) [44]. At a median follow-up of 18 months length
of rectal remnant was shown to be a significant predictor of major
LARS (adjusted OR 0.73, 95% CI 0.55 – 0.93) [41]. In this study, 46%
of the 125 patients with a rectal remnant less than 4cm had major
LARS versus 10% of patients with a remnant greater than 4cm [41]. A
Japanese group also found a significant association between tumour
distance (≤ 4 cm vs. >4 cm) from the anal verge and major LARS on
univariate and multivariate (hazard ratio (HR) 2.72, 95% CI 1.04 –
7.58) analysis, at a median follow-up of 6.5 years [45]. Interestingly,
the most recent publication from the Dutch TME trial, at a median
follow-up of 14.6 years, did not find the distance of the tumour
from the anal verge to be a significant predictor of major LARS on
multivariate analysis [46].
Pre-operative radiotherapy
Preoperative radiotherapy has repeatedly been shown to negatively
impact on post-rectal resection bowel function [47-49]. The Cochrane
Collaboration reported a risk ratio (RR) of 2.12 (95% CI 1.49–3.03, p<
0.01) for incontinence in favour of patients undergoing surgery alone
compared to patients undergoing radiotherapy and surgery [47]. The
relative risk of poor functional outcome when frequency, continence,
and tenesmus data were pooled was not significant (RR 1.69, 95%
CI 0.97–2.94) [47]. A subsequent meta-analysis reported a RR of
1.67 (95% CI 1.36–2.05, p< 0.01) for incontinence in favour of nonirradiated
patients but no significant difference for bowel frequency
(weighted mean difference (WMD) = 0.01) [48]. Despite a significant
volume of literature addressing the question of radiotherapy on
functional outcome after rectal surgery the Cochrane analysis was
only able to pool data from two randomized controlled trials (RCTs)
and the subsequent meta-analysis pooled data from three studies for
each outcome. This highlights the major heterogeneity in reporting
functional outcomes.
Findings from large RCTs show that radiotherapy has a negative
impact on long-term functional outcome after rectal cancer resection
using TME. The following discussion concentrates on assessments
reported at the most recent follow-up for the Stockholm [50,51],
Swedish Rectal Cancer [52], and Dutch TME [53] trials. At 15 years
follow-up the Stockholm trials reported a significant difference in
faecal incontinence for patients receiving radiotherapy versus those
undergoing surgery alone (57% vs. 26%) [54]. The Swedish RCT found
that irradiated patients reported significantly worse function 5 years
after anterior resection in terms of frequency, urgency, emptying
difficulties, early return to the toilet, incontinence (gas, liquid, and
solid stool), pad use, and perineal excoriation [55]. At a median
follow-up of 14.6 years the Dutch TME trial reported significantly
higher rates of major LARS (55.9% vs. 35.5%, OR 3) and of each item
in the LARS score except flatus incontinence, for patients undergoing
pre-operative radiotherapy [46]. The average anastomotic height did
not differ between the groups in the Swedish trials but there were
more low anterior resections in the surgery only group at the most
recent follow-up of the Dutch TME trial [46,54,55]. A multicentre
RCT that enrolled patients with low rectal cancer undergoing
coloanal anastomosis found that despite pre-operative and early
post-operative differences in frequency, pad use, and urgency, at 2
years the only functional difference for irradiated patients was greater
use of antidiarrhoeal agents [56]. The significant association between
poor functional outcome and pre-operative radiotherapy appears to
be weakened when only low rectal cancers (or coloanal anastomoses)
are included. This highlights the interaction between radiotherapy
and anastomotic height as contributors to functional outcome.
To better inform patients about the likely functional outcomes
after treatment for rectal cancer Battersby and colleagues made
a consent aid based on their findings from a multicentre trial that
reported outcomes at an average follow-up of 5 years [40]. They
found that tumour height (OR 1.74 for low vs. high/mid rectal
cancer) and preoperative radiotherapy (OR 1.67) were the only
significant predictors of bowel-related quality of life [40]. Their results
suggest that patients with high or mid rectal cancer who do not have
preoperative radiotherapy have the best chance of a good functional
outcome, with a 33% risk of major bowel impairment [40]. Patients
with low rectal cancer who undergo pre-operative radiotherapy have
the worst functional outcomes, with a risk of major bowel impairment
of 60% but a risk of any bowel impairment of 93% [40]!
Reconstruction technique
Anastomotic height and use of neoadjuvant radiotherapy are
largely dictated by tumour characteristics and cannot be modified
without sacrificing oncological outcomes. Therefore extensive
research has been undertaken to investigate whether surgical
reconstruction can improve functional outcome. Surgeons have
attempted to create a neo-reservoir to alleviate the issues associated
with straight (end to end) anastomoses such as high rates of faecal
incontinence, faecal urgency, and increased stool frequency [57]. The
neo-reservoir takes one of three forms: the side to end anastomosis
[58], the colonic J pouch [12,13], or the transverse coloplasty [59].
The side to end anastomosis was described by Baker in 1950, and was
purported to be technically easier and result in better post-operative
function than the end to end anastomosis [58]. Subsequently, the
J shaped colonic pouch was introduced to give a larger reservoir
[12,13]. The transverse coloplasty involves creating a longitudinal
colostomy across the site of the anastomosis that is closed transversely
to create a neo-reservoir [59]. The optimal size of the reservoir has
been investigated for both pouch reconstructions and side to end
anastomoses. Pouches of varying sizes, ranging from 5 cm to 12
cm, have been studied and smaller pouches seem to result in less
evacuatory dysfunction [60-62]. The size of the side limb (3 cm or
5 cm) in an end to side anastomosis does not impact on functional
outcome [63]. Use of the sigmoid colon, rather than the descending
colon, for J pouch creation has been favoured due to technical ease
and lack of functional benefit with either technique, except in the
presence of significant diverticular disease [64]. A stapled pouch
anastomosis resulted in less urgency (5% vs. 37%) than a hand sewn
anastomosis in one study [65].
Multiple RCTS and meta-analyses have examined which
reconstruction gives the best functional outcome, often with
conflicting results [66-73]. Few studies have compared side to end
vs. end to end anastomoses but one RCT published recently reported
less incontinence and reduced stool frequency with an end to end
anastomosis up to 6 months post-operatively [74]. Colonic J pouch
reconstruction has been reported to result in favourable outcomes
compared to straight anastomoses in terms of stool frequency [67,73],
urgency [67,71,73], night-time soiling [73], antidiarrhoeal use [67,73]
and prolonged evacuation [75], at various follow-up time points. One
meta-analysis reported less laxative use after straight anastomosis
compared to J pouch reconstruction at intermediate follow-up (6
months to 3 years) [75]. More frequently, meta-analyses have found
no difference in functional outcomes between straight anastomoses
and J pouch reconstructions in regards to; stool frequency, pad use,
enema use, use of bowel medication, incomplete defecation, and
faecal incontinence [67,71,75]. A Cochrane review concluded that
until 18 months post-operatively a colonic J pouch reconstruction had
superior function to a straight anastomosis, but there was insufficient
data to compare the functional outcome after 18 months [67].
Few studies have compared outcomes after a side to end (or latero–
terminal anastomosis) to outcomes after a pouch reconstruction and
only one systematic review addresses this comparison [75]. There is
some evidence for better function; stool frequency [76-78], urgency
[77], continence [77,78], and ability to empty the bowel within 15
minutes [79], after pouch reconstruction. Although one study found
that patients had more problems with incomplete evacuation with
a pouch reconstruction when compared to patients with a side to
end anastomosis [76]. However, many RCTs report no difference in
functional outcome with either reconstruction method [80,81] and
a Cochrane review found no difference in stool frequency, urgency,
incontinence, or antidiarrhoeal use with either method [67].
A Cochrane review [67] and a meta-analysis [69] comparing J
pouch reconstruction to transverse coloplasty found no significant
differences in functional outcome. However, subsequent metaanalyses
have found significantly worse fragmentation between
6 months to 3 years (OR 0.45) [75], significantly reduced stool
frequency at 12 months (WMD = -0.39), and significantly reduced
nocturnal leakage at 6 months after a transverse coloplasty (OR 5.88)
[70].
Functional outcome is only one consideration. Safety and
feasibility also influence which reconstruction type may be considered.
The colonic J pouch reconstruction may not be feasible in all patients,
particular obese patients with a fatty mesocolon or patients with a
narrow pelvis [82]. Initially there was concern about an increased
rate of anastomotic leak after a transverse coloplasty [83] but multiple
pooled analyses have demonstrated no difference in the rates of
anastomotic leakage with a coloplasty vs. J pouch reconstruction
[67,69,70]. There are no differences in the rate of anastomotic leak
between straight anastomoses and J pouch reconstructions [67].
Ileostomy
Use of a temporary diverting ileostomy has also been implicated
in the development of poor functional outcome after anterior
resection but there have been conflicting results. Two retrospective
reviews [42,84] found diverting ileostomy to be a significant predictor
of functional outcome. One study found use of an ileostomy was as
significant predictor of Wexner score on univariate analysis and
of Fecal Incontinence Quality of Life (FIQL) score on multivariate
analysis [84]. The other retrospective study used a broad definition of
anterior resection syndrome and found ileostomy to be a predictor of
ARS occurrence at 2, 3, 4, and 5 years follow-up even after adjusting
for anastomotic height [42]. A prospective study assessing functional
outcome using the BFI also found temporary ileostomy to be a
significant predictor of poor functional outcome on univariate but not
multivariate analysis [85]. The only study to use the LARS score found
an increased risk of developing major LARS at 12 months follow-up
with use of a temporary ileostomy (OR 4.51) but this disappeared
when the analysis adjusted for tumour height (OR 1.73, 95% CI 0.44–
6.91) [86]. One RCT investigated the effect of diverting ileostomy
on functional outcome after restoration of bowel continuity and
found that the only significant difference was for stool fragmentation
(need to return to the toilet within one hour) [87]. There were no
significant differences in median stool frequency, incontinence, need
for medication to open bowels, difficulty emptying the bowels, or
urgency between patients with and without a temporary ileostomy
[87].
Anastomotic leakage
Multiple studies have assessed the impact of anastomotic leakage
or pelvic infection on functional outcome but most studies have
assessed faecal incontinence solely and only two studies used the
LARS score [46,86]. The majority of studies have found no significant
difference in outcome [42-44,86,88-91] but two case-control studies
[92,93] report a significant difference in functional outcomes after
anastomotic leakage. One study reported significant differences
in stool frequency (4 vs. 2 motions per 24 hours) and urgency
at 30-month follow-up, between patients who had symptomatic
anastomotic leakage (requiring drainage, abscess evident on imaging
or discharged via a fistula or per anus) and those that did not [93].
Another case-control study found that patients with a radiologically
detected, clinically occult, anastomotic leak had significantly lower
scores on the BFI (worse function) at least one year post-operatively
[92]. Major LARS was also found to be independently predicted by
pelvic infection (not otherwise specified) on univariate analysis (HR
4.02, 95% CI 1.13–14.18) in one study but this was not significant on
multivariate analysis [45].
Other factors
Other factors have been investigated as contributors to poor
functional outcome after low anterior resection, including patient age,
gender, and use of adjuvant chemotherapy. Gender has not been shown
to predict poor functional outcome [41-46,84]. Multiple studies have
investigated age as a contributing factor but only one study reported
that age significantly predicted major LARS at a median follow-up of
14.6 years (OR 2.4 for age >75 years vs. age ≤ 75 years, 99% CI 1.1–
5.5) [46]. A retrospective study found post-operative chemotherapy
significantly predicted the occurrence of symptoms that the authors
associated with ARS at 1 year follow-up but not at subsequent followup
[42]. They concluded that chemotherapy resulted in temporary
adverse effects on function rather than persisting ARS [42]. A study of
297 patients found significant differences in frequency and urgency at
12 and 24 months follow-up favoring patients who had radiotherapy
alone compared to patients who had radiotherapy and post-operative
chemotherapy [56]. A study comparing preoperative radiotherapy
and subsequent surgery to a protocol of initial surgery with postoperative
chemotherapy if the circumferential resection margin
(CRM) was less than 1mm found that patients having radiotherapy
had significantly worse faecal incontinence (53.2% vs. 37%) [94].
Conclusion
LARS is common and it is important that patients are adequately informed about the possibility of suffering from bowel dysfunction after low anterior resection, particularly if they also require preoperative radiotherapy. There is extensive literature regarding functional outcome after low anterior resection but inconsistencies in methodology have resulted in an inability to draw robust conclusions about LARS. This review focused on the literature investigating risk factors that contribute to the development of LARS to highlight the significant heterogeneity in reporting of functional outcomes. In particular there are issues with the measurement of LARS and with the focus on faecal incontinence as the sole outcome of interest. With a consensus definition of the symptoms and time frame that constitutes LARS and with consistent application of specifically designed instruments to measure LARS, standardized research can be conducted to further the understanding of this syndrome. Future work is needed to address the definition of LARS and to champion the use of validated tools such as the LARS score to enable meaningfully investigation into the incidence, risk factors, pathophysiology, and treatment of LARS.
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