x
s ummary
surgical treatment of esophageal cancer:
effect of operative Volume on clinical outcomes
U
ncommon in Canada (1700 new cases in 2010) and Québec (300 new cases in men in 2010), esophageal cancer has a rapid progression and is often diagnosed late, with a resulting dismal prognosis. Surger� is the conventional treatment, and different options, such as adjuvant orneoadjuvant chemoradiotherap�, are also proposed.
Esophageal cancer surger� is complex and carries a high risk of postoperative morbidit� and mortalit�.
Over the past three decades, some authors have observed a decrease in the postoperative mortalit�
rate after esophagectom�, which the� attribute to better surgical management at specialized centres b� more experienced surgeons. Yet, the overall 5-�ear survival rates are still low.
Numerous studies have examined the relationship between hospital or surgeon operative volume and the postoperative outcomes of complex procedures, such as esophageal cancer surger�. An increasing number of these studies report a significant inverse association, of var�ing degrees, between surgical volume and postoperative mortalit�, while others could not demonstrate such a relationship. Because of the lack of qualit� and completeness of the data available in the databases, the case-mix differences, and the heterogeneit� of the threshold categories, caution should be exercised when interpreting the results of the studies anal�zed.
The clinical practice guidelines developed b� the National Comprehensive Cancer Network (NCCN), the Belgian Health Care Knowledge Centre (KCE) and the Scottish Intercollegiate Guidelines Network (SIGN) recentl� proposed recommendations concerning the benefit of esophageal resections being performed at high-surgical-volume centres b� experienced surgeons.
In Québec, approximatel� 180 esophagectomies (all diagnoses combined) are performed at about 40 hospitals each year, at 27 of which five or fewer esophagectomies were performed per �ear between 2006 and 2009. During that period, the mortalit�
rate was 5%, which compares favourabl� with that reported elsewhere in the world.
At the request of the Comité de l’évolution des pratiques en oncologie (CEPO), the oncolog�
assessment unit of the Agence d’évaluation des technologies et des modes d’intervention en santé (AETMIS) was given the task of examining the effect of operative volume on clinical outcomes.
This report therefore examines the published scientific literature on this topic in order to assess the relationship between hospital and surgeon volume or surgeon specialt� (thoracic or general surger�) on the one hand, and postoperative mortality on the other, and to attempt to define a surgical volume threshold associated with better qualit� of care.
Methodology
This review summarizes clinical practice guidelines and other recommendations, s�stematic reviews with or without a meta-anal�sis, and reports from health technolog� assessment agencies that have examined the effect of operative volume on outcomes in patients surgicall� treated for esophageal cancer. Original studies published after these reviews were included as well. In terms of endpoints, the vast majorit� of the studies examined onl� postoperative mortalit� during the initial hospital sta� or 30 da�s after the operation. It was also these parameters that were chosen for this anal�sis.
Results
The clinical practice guidelines that discuss an optimal hospital volume threshold arrive at different recommendations. For example, Cancer Care Ontario’s 2005 guidelines recommend, based on expert consensus, a minimum threshold of 20 esophagectomies per �ear for regional tertiar�
care centres (Level 1) and seven esophagectomies per �ear for secondar� care centres (Level 2).
In the United States, the Leapfrog Group, a health-care advisor� agenc� for large American
“Surgical Treatment of Esophageal Cancer: Effect of Operative Volume on Clinical Outcomes” (summar�)
x
companies, recommended, in 2004, a minimum of 13 esophagectomies per centre per �ear, while the guidelines published b� the Agenc� for Healthcare Research and Qualit� (AHRQ) in 2007 set this threshold at six or seven esophagectomies per centre per �ear. In Europe, although a number of guidelines point to the need to centralize esophageal surger� and recommend that it be performed at high-surgical-volume centres b�
experienced surgeons, other organizations, such as the EACTS/ESTS Working Group and the Société Française de Chirurgie Thoracique et Cardio-Vasculaire (SFCTCV), have proposed a minimum threshold of 25esophagectomies per centre per �ear.
The report b� Belgium’s KCE and the s�stematic Australian review b� Gruen et al. are the latest publications that have examined the relationship between operative volume and esophagectom�
outcomes.
Based on the literature data, the Belgian report’s authors conclude that there is an inverse
relationship between hospital and surgeon volume and postoperative mortalit�. On the other hand, in an anal�sis of administrative data obtained from the Minimal Clinical Data and Minimal Financial Data (MCD and MFD) databases for 2004, the�
found an inverse, but not statistically significant, association between surgeon volume and 3-month mortalit� (13.5% for surgeons who perform fewer than six operations a �ear and 6.4% for those who perform six or more per �ear). No relationship between hospital volume and 2-�ear mortalit�
was found (43.8% at centres where fewer than six interventions are performed per �ear and 45.4%
at those where six or more are performed). The authors conclude that the evidence is insufficient for recommending the centralization of esophageal cancer surger� and suggest that the association between surgical volume and outcomes be reexamined on the basis of more-recent studies involving a several-�ear follow-up.
The Australian meta-anal�sis b� Gruen et al., which was based on 45,822 patients, concludes that there is an inverse, but non-robust,
relationship between hospital surgical volume and short- or long-term mortalit� (OR = 0.81;
95% CI: 0.77-0.84). Few studies have explored the relationship between surgeon volume and short- or long-term mortalit�, and the� show a statistically significant inverse association between these two variables. Other review studies arrive at similar conclusions, namel�, that there appears to be a relationship between surgical volume and postoperative outcomes, but that it is impossible to establish a threshold that would guarantee the best outcomes.
Eleven original studies, most of which were retrospective studies published after the closing date for the above-mentioned reviews, were anal�zed. The� include eight population studies (clinical administrative databases) and three studies based on clinical data. These studies examined the effect of surgical volume per hospital (six studies), per hospital and according to the surgeon’s
specialt� (general or cardiothoracic surger�) (one stud�), per surgeon (three studies) and according to the surgeon’s specialt� (one stud�).
The methodological qualit� of these studies is compromised for three main reasons: 1) the limitations inherent in population studies based on administrative data, such as incomplete or missing data and a lack of data on at-home deaths; 2) the variabilit� in categories of surgical volume thresholds; and 3) the degree to which the postoperative mortalit� risk variables other than surgical volume were adjusted (the case-mix, the hospitals’ characteristics, the length of follow-up, etc.). The authors of the KCE report, Gruen et al.’s s�stematic review as well as most review studies have also noted these weaknesses.
Most original and review studies therefore conclude that there is an inversel� proportional relationship between hospital or surgeon volume and the risk of short-term postoperative mortalit�.
Outcomes are also associated with the surgeon’s specialt�. However, because of the methodological weaknesses found in these studies, accurate conclusions cannot be drawn from them.
“Surgical Treatment of Esophageal Cancer: Effect of Operative Volume on Clinical Outcomes” (summar�)
x
Conclusions
From this anal�sis, based on the recommendations in other jurisdictions and on studies whose
methodological weaknesses and heterogeneit�
call for caution when interpreting their results, AETMIS arrives at the following conclusions:
With regard to surgical volume:
There is an inverse association between hospital or surgeon volume and postoperative mortalit�.
With regard to the surgeon's specialt�:
The association between the surgeon's specialt�
and surgical outcomes is not sufficiently explored b� the studies.
With regard to standard thresholds:
The literature proposes several categories of high and low hospital or surgeon volume but do not define the threshold for designating centres of excellence for complex surgeries, such as esophagectomies. However, the organizations that have addressed this matter in Canada, the United States and Europe have set minimum thresholds ranging from 6 to 25 esophagectomies per �ear.
With regard to the organization of services:
The beneficial effect attributed to hospital or surgeon volume might be closel� associated with the hospital's characteristics, such as patient management b� a multidisciplinar�
team or the expertise of the health professionals (oncologists, anesthesiologists, intraoperative and postoperative care team, intensive care, etc.). These organizational aspects could be associated with a high annual volume of esophagectomies.
Esophagectom� is a complex surgical procedure that should be reserved for high-surgical-volume facilities and performed b� surgeons with extensive experience in this t�pe of surger� or even a
subspecialt� in thoracic surger�.
In Québec, the hospital databases should be used to perform a more detailed comparison of the postoperative mortalit� rates observed in hospitals with different esophagectom� volumes and obtain a picture of their qualit� of care.
“Surgical Treatment of Esophageal Cancer: Effect of Operative Volume on Clinical Outcomes” (summar�)
