Why i.p. therapy cannot yet be considered as a standard of care for the first-line treatment of ovarian cancer: a systematic review

A National Cancer Institute (NCI) clinical announcement recommended i.p. therapy for women with optimally debulked ovarian cancer. Its basis was a summary of eight randomised controlled trials and two systematic reviews, which appear to indicate benefit of i.p. therapy. However, the systematic reviews that inform the recommendations have been inappropriately presented and interpreted. The systematic reviews inappropriately pooled results from 'confounded' trials in which different drugs and different doses of drugs were given in the control and i.p. treatment arms. Therefore, it is not possible to assess which component of treatment is responsible for improving outcome. In addition, none of the trials use a control arm of the internationally accepted standard of care. Using just the unconfounded trials, indirect comparisons show that the magnitude of benefit observed when i.p. regimens are compared with older i.v. regimens [hazard ratio (HR) for overall survival (OS) 0.75; 95% confidence interval (CI) 0.60-0.92,P = 0.006] is smaller than the magnitude of benefit achieved with modern day standard of i.v. treatment compared with the same i.v. regimen used as control in the unconfounded i.p. trials (HR for OS 0.68; 95% CI 0.58-0.80,P < 0.001). A further difficulty is that the reviews cannot recommend an i.p. regimen for standard use. Drug-related toxicity and catheter complications that occur with i.p. therapy are considerable. The NCI recommendations have major implications for the treatment of women with ovarian cancer and for the next generation of clinical trials. We do not believe that the body of evidence currently available supports the recommendation that i.p. therapy should form part of routine care. The choice of treatment of women with newly diagnosed, optimally debulked, ovarian cancer, where therapy has the best chance of influencing OS, is too important to be left with this uncertainty. A clinical trial that investigates a practical and acceptable regimen which gives some or all chemotherapy by the i.p. route and compares this with standard i.v. chemotherapy should be a priority for those who wish to promote its use.