Outcome following surgery for colorectal cancer

Outcome following surgery for colorectal cancer Colin S McArdle* and David J Hole *University Department of Surgery, Glasgow Royal Infirmary, Glasgow and Department of Public Health, University of Glasgow, Glasgow, UK Correspondence to: Prof. Colin S McArdle, University Department of Surgery, Glasgow Royal Infirmary, Glasgow G31 2ER, UK There is evidence to suggest that survival following surgery for colorectal cancer is improving. Audits undertaken in a single institution between 1974 1979 and 1991 1994 provide the opportunity to evaluate the extent to which earlier diagnosis and better surgery contribute to the improvement in survival. There was little evidence that patients were presenting at an earlier stage during the latter period. In contrast, more patients had a potentially curative resection. This analysis confirmed that, over this period, there has been a substantial improvement in survival following surgery for colorectal cancer; this improvement was largely due to better surgery rather than earlier presentation. Colorectal cancer remains the second commonest cause of cancer death in North America and Western Europe. Each year, there are approximately 600,000 new cases diagnosed world-wide. There are more than 130,000 new cases in the US and more than 28,000 in the UK. In the UK, the incidence of colorectal cancer has been slowly increasing especially in men 1,2, whereas in the US there is evidence that the incidence is now falling 3. Survival has increased both in the UK (Table 1) 1,2 and the US 3. Although registry-based data contain information on age, sex and deprivation, such data do not have information on mode of presentation, stage at diagnosis, the nature of surgery, whether a curative resection was achieved and whether the patient received adjuvant therapy. It is, therefore, not clear whether the observed improvement in survival is due to earlier diagnosis or better treatment. Table 1 Relative survival rate (%) at 5 years (Scotland) 1971 1975 1991 1995 Males Colon 32.0 47.4 Rectum 30.6 45.2 Females Colon 34.8 49.5 Rectum 32.9 51.4 : 119 125 The British Council 2002

Advances in colorectal cancer Table 2 Relationship between age and baseline characteristics (%) < 75 years 75 years P value (n = 2077) (n = 1123) Female 46 56 < 0.001 Deprivation 20 17 0.216 Emergency 28 37 < 0.001 Colon 62 69 < 0.001 Dukes stage A/B 49 53 0.002 Curative resection 70 70 0.508 * P < 0.001 A recent audit of patients presenting with colorectal cancer to hospitals in central Scotland between 1991 1994 provides an opportunity to evaluate the extent to which individual factors contribute to the overall improvement in survival 4. Of the 3200 patients included in the analysis, 35% were aged 75 years or over, 19% were socio-economically deprived, 31% presented as an emergency, and 15% had evidence of metastatic spread at the time of surgery. Of these 3200 patients, 2235 (70%) underwent apparently curative resection and 965 palliative resection. Postoperative mortality was 4.3% following curative resection and 9.8% after palliative resection. Of the total, 5% of patients received adjuvant therapy. There were 2108 deaths. Overall, 52% of those undergoing apparently curative resection survived 5 years and 26% of those undergoing palliative resection survived 2 years. Cancer-specific survival after apparently curative resection was 66% at 5 years; cancer-specific survival following palliative resection was 29% at 2 years. Age, sex and deprivation were to some extent interlinked. Older patients tended to present as an emergency, have colonic tumours, and have less advanced disease at the time of diagnosis (Table 2). There was no difference in the proportion of elderly patients undergoing potentially curative resection. Older patients were more likely to die Table 3 Relationship between age, type of surgery, postoperative mortality and survival Type of resection Age Postoperative Overall Cancer-specific (years) mortality survival survival Curative (5 years) < 75 2.5 58.8 68.6 75 7.7* 40.5* 60.9* Palliative (2 years) < 75 6.6 29.2 31.9 75 16.0* 20.5* 26.7* 120

Outcome following surgery for colorectal cancer Table 4 Relationship between gender and baseline characteristics (%) Male Female P value (n = 1606) (n = 1594) Age 75 years 30 40 < 0.001 Deprivation 21 18 0.10 Emergency 28 34 < 0.001 Colon 61 68 < 0.001 Dukes stage A/B 50 52 < 0.001 Curative resection 67 72 0.004 following surgery, especially palliative surgery, more likely to die of their disease, and more likely to succumb to intercurrent illness (Table 3). Females tended to be older, have right-sided tumours, present as an emergency, have less advanced disease, and were more likely to undergo potentially curative resection (Table 4) 5. There was no difference in postoperative mortality between the sexes. Both overall and cancerspecific survival following potentially curative resection was higher in females than males (Table 5). Table 5 Relationship between gender, type of surgery, postoperative mortality and survival Type of resection Gender Postoperative Overall Cancer-specific mortality survival survival Curative (5 years) Male 4.5 49.1 64.4 Female 4.2 55.2* 67.3 Palliative (2 years) Male 10.2 27.4 31.1 *P < 0.001. Female 9.5 24.8 28.9 Table 6 Relationship between deprivation and baseline characteristics (%) Non-deprived Deprived P value (n = 1871) (n = 398) Age 75 years 34 31 0.19 Female 51 51 0.31 Emergency 32 31 0.80 Colon 66 60 0.02 Dukes stage A/B 50 49 0.85 Curative resection 69 72 0.52 121

Advances in colorectal cancer Table 7 survival Relationship between deprivation, type of surgery, postoperative mortality and Type of resection Deprivation Postoperative Overall Cancer-specific mortality survival survival Curative (5 years) Non-deprived 4.3 52.6 65.7 Deprived 4.2 47.0* 62.6* Palliative (2 years) Non-deprived 9.4 25.5 28.8 Deprived 11.7 25.2 29.3 *P < 0.05. There was no difference in age, gender, mode of presentation, extent of disease at diagnosis, type of resection or postoperative mortality between the affluent and deprived (Table 6) 6. More of the deprived patients had rectal cancers. Following potentially curative resection, overall and cancer-specific survival was poorer in the deprived (Table 7). Patients who presented as an emergency tended to be older, female, have colonic tumours, have more advanced disease, and were less likely to undergo potentially curative resection (Table 8). Postoperative mortality was higher in the emergency group; overall and cancer-specific survival was lower (Table 9). Table 8 Relationship between mode of presentation and baseline characteristics (%) Table 9 Relationship between mode of presentation, type of surgery, postoperative mortality and survival Type of resection Mode of Postoperative Overall Cancer-specific presentation mortality survival survival Curative (5 years) Elective 2.8 57.5 70.9 Emergency 8.2* 39.1* 52.9* Palliative (2 years) Elective 5.9 31.6 35.2 Emergency 16.7* 17.0* 21.0* *P < 0.001. Elective Emergency P value (n = 2214) (n = 986) Age 75 years 32 42 < 0.001 Female 48 55 < 0.001 Deprivation 19 20 0.12 Colon 57 81 < 0.001 Dukes stage A/B 53 46 < 0.001 Curative resection 72 64 < 0.001 122

Outcome following surgery for colorectal cancer Table 10 Comparison of baseline characteristics of patients (%) treated between 1974 1979 and 1991 1994 at Glasgow Royal Infirmary 1974 1979 1991 1994 P value (n = 645) (n = 354) Age 75 years 22 34 < 0.001 Female 50 44 0.07 Emergency 34 34 1.00 Colon 64 60 0.008 Dukes stage A/B 45 51 0.15 Curative resection 52 56 0.013 Resection rate 71 80 0.002 Table 11 Comparison of postoperative mortality and survival in patients treated between 1974 1979 and 1991 1994 at Glasgow Royal Infirmary Type of resection Date of Postoperative Overall Cancer-specific study mortality survival survival Curative (5 years) 1974 1979 6.2 38.5 45.2 1991 1994 4.5 61.3*** 72.6*** Palliative (2 years) 1974 1979 14.2 16.7 19.3 1991 1994 12.9 27.1* 32.4** *P < 0.05; **P < 0.01; ***P < 0.001. To address the question of whether the observed improvement in survival was due to earlier diagnosis or better surgery, we compared outcome between 1974 1979 and 1991 1994 in a single institution (Glasgow Royal Infirmary). The overall resection rate was higher and, during the latter period, the proportion of patients who underwent potentially curative resection increased (Table 10). Furthermore, between 1974 1979 and 1991 1994, postoperative mortality decreased, and overall and cancer-specific survival following potentially curative resection increased (Table 11). There was little evidence that patients were presenting at an earlier stage during the latter period, since the proportion presenting as an emergency was unchanged and, although there was a trend towards more patients with Dukes stage A/B tumours, this was not significant. Earlier presentation would, therefore, not appear to be the underlying reason for the reduction in mortality in the latter period. In contrast, more patients had their tumour resected and more had a potentially curative resection. This increase in the resection rates was achieved in parallel with a reduction in postoperative mortality. This 123

Advances in colorectal cancer Conclusions References suggests that better peri-operative care and improved surgical technique have been the main factors underlying the substantial reduction in mortality. There are two possible explanations for the differences in outcome, namely the number of patients treated by each surgeon and whether these surgeons were specialists or not. One large study reported that high-volume surgeons had lower postoperative mortality rates compared to low-volume surgeons, but the absolute magnitude of the difference was small 7. However, the majority of studies which have addressed this question have failed to demonstrate significant relationship between case volume and postoperative mortality 8,9, local recurrence 9,10 or survival 9,11,12. The question of specialisation is more complex. The best evidence to date comes from the Swedish and Canadian studies. Analysis of 1399 rectal cancer patients, randomised within the Swedish pre-operative radiotherapy studies, showed that local recurrence rates were lower and survival rates significantly higher in those patients treated by surgeons with more than 10 years experience as a specialist 9. In the smaller Canadian study, rectal cancer patients treated by colorectal-trained surgeons had significantly lower local recurrence rates and higher cancer specific survival rates, independent of caseload 13. This analysis confirms that, over the last two decades at a time when adjuvant chemotherapy was hardly used, there has been a substantial improvement in survival following surgery for colorectal cancer. This improvement is largely due to better surgery and the development of specialisation rather than earlier presentation. As the proportion of patients with colorectal cancer treated by specialist colorectal surgeons increases, one might anticipate that further substantial improvements in survival will occur. 1 Scottish Cancer Intelligence Unit. Trends in Cancer Survival in Scotland 1971 1995. Edinburgh: Information and Statistics Division, 2000; 54 71 2 Coleman MP, Babb P, Damiecki P et al. Cancer Survival Trends in England and Wales, 1971 1995: Deprivation and NHS Region. London: The Stationary Office, 1999 3 Ries LA, Wingo PA, Miller DS et al. The annual report to the nation on the status of cancer, 1973 1997, with a special section on colorectal cancer. Cancer 2000; 88: 2398 424 4 McArdle CS, Hole DJ. Outcome following surgery for colorectal cancer: analysis by hospital after adjustment for case-mix and deprivation. Br J Cancer 2002; 86: 331 5 124

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