Rutten et al. BMC Cancer 2012, 12:31 http://www.biomedcentral.com/1471-2407/12/31 to be included to achieve a power of 80%. Considering 10% loss to follow-up and protocol violation, we plan to enroll 200 patients. Data analysis The results of the randomized trial will be analyzed according to the intention to treat principle. Difference in the proportion of futile laparotomies in both arms will be tested using a Chi-square test with a two-sided significance level of 0.05. Prognostic value of standard staging and staging with laparoscopy will be expressed as sensitivity, specificity and predictive values. Standard staging and standard staging with laparoscopy is consid- ered true positive when subsequent suboptimal debulk- ing surgery is correctly identified. Overall survival (OS) and progression free survival (PFS) will be measured from the date of randomization to respectively the date of death and first documented date of progression. OS and PFS will be calculated in both arms by the Kaplan- Meier method. Treatment complications will be reported in a contingency table. Quality of life will be compared between both treatment arms at various time points. We will make a subgroup analysis for number of futile laparotomy for each gynaecologic-oncologic cen- tre, FIGO stage and size of metastatic tumour seen at laparoscopy or laparotomy. Economic evaluation The aim of the economic evaluation is to assess whether the laparoscopy can reduce the number of futile primary laparotomies and associated costs to an extent that at least offsets the costs of this laparoscopy in all eligible patients. A strategy that reduces the number of unne- cessary laparotomies is considered preferable, even if this does not improve survival, also if the costs gener- ated by both strategies are comparable. The economic analyses will be conducted from a societal perspective including direct medical and direct non-medical costs. Relevant costs components that will be taken into account are costs of the laparoscopy and laparotomy, operation time, hospital days, interventions for compli- cations and intensive care admission. Indirect costs are associated with home care, consisting of both profes- sional care as well as informal care. Discussion Primary debulking surgery with the aim to leave no resi- dual tumour is still considered as the standard treatment for patients with advanced ovarian cancer. However, more and more patients are submitted to IDS to reas- sure better surgical results. A complete debulking, with- out any residual tumour after surgery, should be pursued to obtain the best prognosis. However, the number of primary surgeries leaving residual tumor of more than 1 cm in diameter, is up to 40%, while during Page 5 of 6 interval debulking surgery more often complete resec- tion is achieved, without affecting survival [19,20] Selecting patients who benefit from primary debulking surgery, i.e. in whom complete surgery results are possi- ble, should be optimized. In several institutes diagnostic laparoscopy is already standard of care to determine further treatment in ovarian cancer patients. Prospective and retrospective studies showed that predictability of surgical outcome with laparoscopy is better than that of standard diagnostic staging [16-18,21]. However, predic- tion models could not be validated in different popula- tions. Furthermore, laparoscopy is an invasive procedure under general anesthesia with a serious morbidity rate of 1‰-5% [22,23]. If laparoscopy before starting treat- ment is a reliable additional diagnostic tool in predicting result of PDS, unsuccessful laparotomies can be pre- vented. This will optimize treatment for the individual patient. To this date no randomized controlled trials have investigated whether additional diagnostic laparo- scopy prevents unsuccessful laparotomies. Acknowledgements This study is funded by The Dutch organization for Health Research and Development (ZonMW) grant 80-82310-97-11056 Author details 1Department of Obstetrics and Gynaecology, Academic Medical Centre, Amsterdam, The Netherlands. 2Department of Obstetrics and Gynaecology, Leiden University Medical Center, Leiden, The Netherlands. 3Department of Obstetrics and Gynaecology, Maastricht University Medical Center, GROW - School for Oncology and Developmental Biology, Maastricht, The Netherlands. 4Department of Gynaecology, University Medical Center Groningen, Groningen, The Netherlands. 5Department of Clinical Epidemiology Biostatistics and Bioinformatics, Academic Medical Centre, Amsterdam, The Netherlands. 6Department of Obstetrics and Gynaecology, Isala Klinieken Zwolle, Zwolle, The Netherlands. 7Department of Obstetrics and Gynaecology, Catharina Hospital Eindhoven, Eindhoven, The Netherlands. 8Clinical Research Unit, Academic Medical Centre, Amsterdam, The Netherlands. 9Department of Obstetrics and Gynaecology, TweeSteden hospital Tilburg, Tilburg, The Netherlands. 10Department of Obstetrics and Gynaecology, University Medical Center Utrecht, Utrecht, The Netherlands. 11Department of Obstetrics and Gynaecology, Medisch Spectrum Twente, Enschede, The Netherlands. 12Department of Radiology, Academic Medical Centre Amsterdam, Amsterdam, The Netherlands. 13Department of Obstetrics and Gynaecology, Erasmus Medical Centre, Rotterdam, The Netherlands. 14Department of Obstetrics and Gynaecology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands. Authors’ contributions MRB, GGK, PB, BO, BWM and MJR were involved in conception and design of the study. MJR and MRB drafted the first manuscript. All authors edited the manuscript and read and approved the final draft. Competing interests The authors declare that they have no competing interests. Received: 11 January 2012 Accepted: 20 January 2012 Published: 20 January 2012 References 1. Elattar A, Bryant A, Winter-Roach BA, Hatem M, Naik R: Optimal primary surgical treatment for advanced epithelial ovarian cancer. Cochrane Database Syst Rev 2011, 8:CD007565.