Biphasic learning curve of cytoreductive surgery and hyperthermic intraperitoneal chemotherapy: technical competence and refinement of patient selection

Background: Cytoreductive surgery (CRS) with hyperthermic intraperitoneal chemotherapy (HIPEC) is routinely used for selected patients with peritoneal metastasis, but can be associated with high complication rates, prolonged hospital stay, and mortality. Our objective was to determine the learning curve of CRS/HIPEC in our institution, representing the largest Asian cohort to date. Methods: A total of 200 consecutive patients with peritoneal metastasis treated with CRS/HIPEC between 2001 and 2016 were grouped into four cohorts of 50 patients and studied. Primary outcomes were severe morbidity (Clavien-Dindo III-V), procedure-related mortality, and duration of ICU and hospital stays. Secondary outcome was duration of surgery. Results: Median age was 53 years (10-75). There was no significant age, sex, or histology difference across cohorts. Rates of severe morbidity (23 %), and 60 day inpatient mortality (0.5 %) were comparable to previously reported data. Decreases in rates of serious morbidity, (34 %, 30 %, 12 %, 14 %, p < 0.01) and duration of total hospital stay (14, 16, 13, 12 days, p = 0.041) were seen across consecutive cohorts. Operation time decreased significantly after the first cohort (10, 7.8, 7.8, 7.2 h, p < 0.01), despite increase in average PCI score after the first cohort (8, 14, 12, 13, p = 0.063). Conclusions: Whilst 50 cases were adequate for procedural familiarity and decreased average operation time, significant improvement in rate of serious morbidity was observed after 100 operations. We demonstrate a novel biphasic nature to the learning curve, reflecting initial training in which technical competence is achieved, followed by a subsequent period characterized by increasingly complex cases (higher PCI score) and finally refinement of patient selection.