The results of our study suggest that the risk of death by 3 years after diagnosis of pancreatic cancer is 37% lower among patients undergoing surgical intervention who are managed by specialist pancreatic surgeons or clinicians with an interest in this field. No advantage of specialisation was seen for the total patient population, but this probably reflects the fact that surgical resection offers the best chance of survival (Wade et al, 1994
; Bramhall et al, 1995
; Sener et al, 1999
), at least for localised disease (Wade et al, 1995
The resection rate of 4.7% in this study was low by international standards (Edge et al, 1993
; Baumel et al, 1994
; Nakao and Takagi, 1998
), but may reflect the small number of patients managed by specialist pancreatic surgeons or clinicians with an interest in this field (12.1% of cohort). However, the resection rate did increase from 3.8% in 1993 to 5.2% in 1997. The development of regional cancer networks in the United Kingdom in recent years and the requirement for all patients with cancer to be discussed at multidisciplinary meetings may result in more patients being considered for potentially curative surgery. Bachmann et al (2003)
suggested that patients referred to less specialised doctors or hospitals were less likely to be investigated thoroughly, or to undergo palliative or potentially curative treatment.
Several studies (Edge et al, 1993
; Gordon et al, 1995
; Lieberman et al, 1995
; Neoptolemos et al, 1997
; Gouma et al, 2000
; Garden, 2001
; NHS Executive, 2001
; Rosemurgy et al, 2001
; Teisberg et al, 2001
; Birkmeyer et al, 2002
; Halm et al, 2002
; Bachmann et al, 2003
) have suggested that specialisation in this field may yield better results in terms of postoperative mortality, surgical complications, and longer term survival, although other studies have not found this relationship (Wade et al, 1994
), and the possibility of publication bias must be considered. Some previous studies are subject to the criticism that in-hospital mortality was used as an outcome, despite the fact that length of stay may be lower in patients treated by specialist pancreatic surgeons or hospitals with higher caseloads (Imperato et al, 1996
; Sosa et al, 1998
; Gordon et al, 1999
; Simunovic et al, 1999
; Rosemurgy et al, 2001
). Most of the studies used hospital or surgeon caseload as a proxy for specialisation, and while this may be a reasonable assumption, others have argued that there is no proof that repeating a procedure hundreds of times necessarily guarantees competence (Loefler, 2000
). In our own study, when all patients were considered together, survival was significantly higher for patients treated by consultants dealing with larger caseloads, but this factor was not significant in the model concerning only surgical patients. Although our categorisation of specialist status might be construed as subjective compared to any definition based on caseload, it was assigned before analysis.
A major strength of our study is the fact that it is population-based and not therefore subject to some of the potential biases inherent in single institution-based studies. However, the study is based on data collected routinely and not specifically to fulfil the aims of the study. Although data quality is believed to be reasonable (Harley and Jones, 1996
; Brewster et al, 1997
), it is unlikely to be as high nor as detailed as if the data had been collected prospectively. We were obliged to accept the reality that, in this and many other countries (Parkin et al, 2002
), a high proportion of pancreatic cancers have no information on precise subsite of origin, and are not verified by microscopy. However, given the very poor survival prospects for patients registered with pancreatic cancer in Scotland (Scottish Cancer Intelligence Unit, 2000
), it seems unlikely that the cancer registry includes many clinically diagnosed cases of pancreatic cancer that are actually cases of benign pancreatic disease. Restriction of our analyses to microscopically verified cases only would, in our opinion, have introduced a substantial risk of bias.
Given the importance of tumour stage as a prognostic variable (Wade et al, 1995
), the absence of this variable is an acknowledged limitation, although its importance as a discriminating variable may be less among the cohort of patients undergoing surgery. Although we cannot exclude residual confounding as an explanation for our results, it seems counter-intuitive that surgical patients with more favourable subsites of origin, more limited disease, and requiring less technically demanding procedures would be referred selectively to specialist surgeons. In relation to the variables available for our study, it is likely that some misclassification exists, although if this is random with respect to specialist status, it will have attenuated rather than exaggerated the differences in outcome by this factor. The prognostic impact of other factors, such as age, presence of metastases at diagnosis and co-morbidity, is plausible and expected. Although microscopic verification of diagnosis appears to have no statistically significant effect on the survival of all patients combined, it is associated with higher survival in surgical patients, presumably because resection is always likely to result in tissue diagnosis.
It is interesting to note that, although almost 90% of patients were treated in high volume hospitals, slightly less than half were managed by consultants treating 10 or more cases (). Thus, any shift in referral patterns towards higher volume surgeons may not have a substantial impact on patient travel times.
When considering the policy implications of the present study and related studies, it is important to acknowledge that not everyone is convinced of the merits of specialisation which does have some theoretical disadvantages (Loefler, 2000
). However, the body of evidence is now such that we would suggest that the onus is on sceptics to provide evidence that surgical specialisation offers no advantages, or at least that the disadvantages outweigh the benefits. From a pragmatic point of view, we believe that the individual faced with a diagnosis of pancreatic cancer would wish to be managed by a multidisciplinary team including a surgeon with specific training in this area and an annual caseload above a certain minimum threshold.
In conclusion, we have shown that surgically treated patients with pancreatic cancer are likely to fare better if they are managed by specialist pancreatic surgeons, or clinicians with an interest in this field. Although we cannot exclude entirely the possibility of bias or confounding, our results add to a growing body of evidence supporting specialisation of surgery for pancreatic malignancy. This has major implications for the delivery of cancer services in Scotland and the rest of the UK.