This study is the largest one to date with only 37 patients (matched to 61 PM patients). The presence of concomitant HM was shown to be an independent prognostic factor. The three-year disease-free survival was poor at only 6%. Their conclusion was that synchronous PM and HM disease was feasible to operate but that the PCI score should be lower Inhibitors,research,lifescience,medical than 12 and that the number of HM should be max 2. This differs from the earlier Milano consensus, which puts the limit at three (16). Table 4 Comparison of studies reporting outcome in combined treatment of PM and HM The aim of our study was to

provide matched groups according to the most important prognostic indicators: PCI, surgical result, and type of IPC (7,8,17). The matching was successful and comparison of clinical

Inhibitors,research,lifescience,medical and surgical variables was highly congruous. Besides the difference of HM, only one out of the other 26 variables was statistically different (number of gastrointestinal resections) and only one other variable was close at P=0.06 (more low tumour grade in the PM group). Inhibitors,research,lifescience,medical In order to ascertain the effect of these differences a univariate and a multivariable Cox proportional hazard regression was performed. Both the number of gastrointestinal resections and tumour grade had no statistically significant effect on the overall survival (Table 3). After these analyses results, the effect of HM on the overall survival was evaluated. Two methods were used, the two-tailed log rank test of a Kaplan-Meier curve (Figures 1,​,2)2) and the Cox proportional hazard regression (Table 3). The overall survival did not appear to be statistically effected by the presence and concomitant treatment of HM; but, the study does not have enough Inhibitors,research,lifescience,medical power to ascertain this adequately. On the other hand, there was a clear tendency toward lower DFS in the PM/HM group as seen in Figure 2. When comparing recurrences between the groups, it becomes increasingly clear that there is a significantly higher risk of recurrence in the PM/HM group. Currently, only 1/10 (10%) R1 resections in the PM/HM Inhibitors,research,lifescience,medical group remains disease free, while

9/20 (45%) is disease free in the PM group (P=0.05). Furthermore, it is interesting that the PM/HM group recurs almost twice as much regardless of location compared nearly to the PM group. This is an interesting finding as it supports the find more notion that some patients with isolated PM disease may have a different metastatic profile and potential. One may speculate that the genetic mutations needed for hematogenic growth has not yet been acquired in many patients with isolated PM. This may also be the reason that some patients become eligible for repeat cytoreductive procedures (18). Figure 2 Disease-free survival of colorectal peritoneal and hepatic metastases (PM/HM) vs. peritoneal metastases (PM) alone, P=0.1 Most studies report on the overall survival as seen in Table 4. Now, this is, of course, a relevant aspect.