3. Evolution of the concept of cytoreductive surgery

As early as in 1934, Meigs described that 'removal of as much tumour as possible' was beneficial for survival [2]. In 1968 the British gynaecological surgeon Hudson described a pioneering technique for the resection of ovarian cancer from the pelvis [3]. Although there have been modifications, the principles have remained the same and his procedure is recognised as the 'radical oophorectomy'. This was an important step in CRS. In fact it was the seminal work of Griffith's published in 1975 which demonstrated that CRS associated with smaller residual disease, can be linked to better survival in advanced ovarian cancer [4].

Benefits of CRS include removal of poorly vascularised tissues (removing the pharmacological sanctuary) and excising the chemoresistant clones. Therefore the resulting absent or minimal disease will have more favourable cell kinetics with regard to chemosensitivity [5].

As the concept of CRS became more widely embraced, the application became more aggressive. Disease on the diaphragm, large bowel, spleen or distal pancreas might have been considered unresectable are now readily resected. Patient selection for these ultraradical procedures is important. This was a concern for the doubters as it may be associated with greater risk of morbidity, delay in receiving chemotherapy as well as significant impact on the quality of life (QOL) [6–8]. Indeed it was felt that perhaps only those with smaller volume and earlier stage disease would benefit from aggressive CRS [5, 9]. However a structured approach to quality improvement through enhanced skills, team structure and commitment to CRS has been shown to improve extent of cytoreduction and hence overall median survival [10–12].

In an important meta-analysis, Bristow demonstrated that greater the volume reduction, greater the survival outcome [13]. In fact they revealed that for every 10% increase in nil residual disease, overall survival increased by 5.5% [13]. Similarly in a more recent metaanalysis of largely newer data in the platinum-taxane era, Chang et al. demonstrated that with each 10% increase in complete cytoreduction, the median overall survival improved by 2.3 months [14].

Three limitations to ultra-radical debulking surgery remain absence of grade A evidence confirming that radical surgery is more efficacious than standard surgery, morbidity/mortality associated with radical CRS and surgery in non-expert centres will only yield nil residual disease in a relatively small proportion of patients [15]. The first two arguments are unlikely to be resolved but one can certainly use big data to resolve treatment pathways for patients with advanced disease.
