Patients
In total, 1248 patients were randomly assigned to either laparoscopic resection or conventional open resection, of which the six participating Dutch centres recruited 329. Of the Dutch patients, 58 were excluded for various reasons (Fig. 1). The first patient inclusion in the Netherlands was at 21 March 1997 and the last at 10 March 2003. In November 2014 collecting of 10-year follow-up data was started. In the laparoscopic and open group, six and nine patients, respectively, had been lost to follow-up, leaving 256 patients for 10-year analysis. Of those, 125 patients were assigned to be operated laparoscopically and 131 patients to be operated through an open procedure (Fig. 1). The median follow-up of all patients was 112 months in the laparoscopic group (range 0.03–198.92) and 111 months in the open group (range 0.10–194.89) (p = 0.83). Median follow-up of survivors was 156 months in the laparoscopic group (range 117.97–198.92) and 150 months in the open group (range 105.11–194.13).
Baseline characteristics showed no significant differences between the two groups (Table 1). Operative and pathological data showed no differences except for length of operative procedure, which was longer in the laparoscopic group (140 vs. 95 min, p < 0.001) and blood loss, which was less in the laparoscopic group (113 vs. 200 mL, p = 0.02). Distribution of disease stage and size of tumour was similar in both groups (Table 2).
Table 1 Patient baseline characteristics
Table 2 Operative and pathological data
Conversion
Of 125 patients who were assigned to undergo a laparoscopic procedure, conversion to open surgery was performed in 40 patients (32 %). In six patients, the decision for conversion was made preoperatively (poor cardiac condition (n = 3), randomisation error (n = 1), extensive T4 tumour (n = 1) and unknown (n = 1)). In 34 patients (27 %), conversion was performed during the operation, reasons for conversion were fixation of the tumour (n = 10), adhesions (n = 3), the tumour could not be identified (n = 8), macroscopic metastases were found (n = 2), other reasons (n = 10), and in one patient, the reason was unknown.
Disease-free survival
The disease-free survival rate at 10 years post-operatively was 45.2 % in the laparoscopic group and 43.2 % in the open group (difference 2.0 %; 95 % confidence interval (CI) −10.3 to 14.3; p = 0.96). In patients with stage I colon cancer, disease-free survival rates were 54.8 and 45.9 % for the laparoscopic and open group, respectively (difference 8.9 %; 95 % CI −16.2 to 34.0; p = 0.52). In patients with stage II disease, these rates were 48.1 and 35.7 % (difference 12.4 %; 95 % CI −5.9 to 30.7; p = 0.22) and in patients with stage III disease 34.2 % in the laparoscopic group and 52.5 % in the open group (difference −18.3 %; 95 % CI −39.9 to 3.3; p = 0.09) (Fig. 2).
Overall survival
At 10-year follow-up, 133 patients had died, 64 in the laparoscopic group and 69 in the open group. Fifty-three patients who died had recurrent disease (27 patients in the laparoscopic group and 26 patients in the open group). The 10-year overall survival rate was 48.4 % in the laparoscopic group and 46.7 % in the open group (difference 1.7 %; 95 % CI −10.6 to 14.0; p = 0.83). In patients with stage I colon cancer, overall survival rates were 58.1 and 52.7 % for the laparoscopic and open group, respectively (difference 5.4 %; 95 % CI −19.7 to 30.5; p = 0.67). In patients with stage II disease, these rates were 51.9 and 41.1 % (difference 10.8 %; 95 % CI −7.8 to 29.4; p = 0.23) and in patients with stage III disease 36.8 % in the laparoscopic group and 50.8 % in the open group (difference −14.0 %; 95 % CI −35.8 to 7.8; p = 0.22) (Figure as Supplementary material).
Recurrences
A total of 62 patients developed recurrent disease during the 10-year follow-up period, accounting for a recurrence rate of 29.4 % in the laparoscopic group and 28.2 % in the open group (difference 1.2 %; 95 % CI −11.1 to 13.5; p = 0.73). In patients with stage I colon cancer, recurrence rates were 19.8 and 22.5 % for the laparoscopic and open group, respectively (difference −2.7 %; 95 % CI −25.2 to 19.8; p = 0.80). In patients with stage II disease, these rates were 21.8 and 27.3 % (difference −5.5 %; 95 % CI −23.7 to 12.7; p = 0.65) and in patients with stage III disease 46.8 % in the laparoscopic group and 35.4 % in the open group (difference 11.4 %; 95 % CI −11.6 to 34.4; p = 0.29) (Fig. 3).
The site of recurrence did not significantly differ between the two groups. In total, 43 patients suffered a locoregional recurrence, 23 patients in the laparoscopic group and 20 patients in the open group. Seven patients had a recurrence in the port- or wound-site, three patients in the laparoscopic and four patients in the open group. The time of occurrence of the port- and wound-site recurrences after surgery was in the laparoscopic group 8.1, 30.9 and 34.7 months and in the open group 16.0, 16.7, 27.5 and 31.2 months. In total, 40 patients were diagnosed with a distant recurrence (19 in the laparoscopic and 21 in the open group), accounting for 69 distant recurrences (Table as Supplementary material).
At 5 years follow-up, 154 patients were alive and free of disease. Between 5 and 10 years after surgery five of these 154 patients (3 %) developed a first recurrence. Three other patients developed a recurrence between 5 and 10 years after surgery as well, and however, in these patients it was not the first recurrence.