What is the optimal chemotherapy treatment for women with recurrent ovarian cancer who have previously received platinum-based chemotherapy?
Currently, standard primary therapy for advanced disease involves a combination of maximal cytoreductive surgery and chemotherapy with carboplatin plus paclitaxel or with carboplatin alone. Despite initial high response rates, a large proportion of patients relapse, resulting in a therapeutic challenge. Because these patients are not curable, the goal of therapy becomes improvement in both quality and length of life. The search has therefore been to find active agents for women with recurrent disease following platinum-based chemotherapy.
Outcomes of interest included any combination of tumour response rate, progression-free survival, overall survival, adverse events, and quality of life.
The medline, embase, and Cochrane Library databases were systematically searched for primary articles and practice guidelines. The resulting evidence informed the development of clinical practice recommendations. The systematic review and recommendations were approved by the Report Approval Panel of the Program in Evidence-Based Care, and by the Gynecology Cancer Disease Site Group (dsg). The practice guideline was externally reviewed by a sample of practitioners from Ontario, Canada.
Thirteen randomized trials compared various chemotherapy regimens for patients with recurrent ovarian cancer.
In five of the thirteen trials in which 100% of patients were considered sensitive to platinum-containing chemotherapy, further platinum-based combination chemotherapy significantly improved response rates (two trials), progression-free survival (four trials), and overall survival (three trials) when compared with single-agent chemotherapy involving carboplatin or paclitaxel. Only two of these randomized trials compared the same chemotherapy regimens: carboplatin alone versus the combination of carboplatin and paclitaxel. Both trials were consistent in reporting improved survival outcomes with the combination of carboplatin and paclitaxel. In one trial, the combination of carboplatin and gemcitabine resulted in significantly higher response rates and improved progression-free survival when compared with carboplatin alone. Median survival with carboplatin alone ranged from 17 months to 24 months in four trials.
In eight of the thirteen trials in which 35%–100% of patients had platinum-refractory or -resistant disease, one trial reported a statistically significant 2-month improvement in overall survival with liposomal doxorubicin as compared with topotecan (15 months vs. 13 months, p = 0.038; hazard ratio: 1.23; 95% confidence interval: 1.01 to 1.50). In that trial, because of the limited clinical benefit and the unusual finding that a survival difference emerged only after a year of treatment with no corresponding improvement in the rate of response or of progression-free survival, the authors concluded that further confirmation by results from randomized trials were needed to establish the superiority of one agent over another in their trial. In one trial, topotecan was superior to treosulphan in patient progression-free survival by a span of approximately 2 months (5.4 months vs. 3.0 months, p < 0.001).
Toxicity was reported in all of the randomized trials, and although data on adverse events varied by treatment regimen, the observed adverse events correlated with known toxicity profiles. As expected, combination chemotherapy was associated with higher rates of adverse events.
This clinical recommendation applies to women with recurrent epithelial ovarian cancer who have previously received platinum-based chemotherapy. Of specific interest are women who have previously shown sensitivity to platinum therapy and those who previously were refractory or resistant to platinum-based chemotherapy. As a general categorization within what is actually a continuum, “platinum sensitivity” refers to disease recurrence 6 months or more after prior platinum-containing chemotherapy, and “platinum resistance” refers to a response to platinum-based chemotherapy followed by relapse less than 6 months after chemotherapy is stopped. “Platinum-refractory disease” refers to a lack of response or to progression while on platinum-based chemotherapy.
Although the body of evidence that informs the clinical recommendations is based on randomized trial data, those data are incomplete. Based on the available data and expert consensus opinion, the Gynecology Cancer dsg makes these recommendations:
Systemic therapy for recurrent ovarian cancer is not curative. It is therefore recognized that each patient must be individually assessed to determine optimal therapy in terms of recurrence, sensitivity to platinum, toxicity, ease of administration, and patient preference. All suitable patients should be offered the opportunity to participate in randomized trials, if available.
In the absence of contraindications, combination platinum-based chemotherapy should be considered for patients with prior sensitivity to platinum-containing chemotherapy. As compared with carboplatin alone, the combination of carboplatin and paclitaxel significantly improved both progression-free and overall survival.
If combination platinum-based chemotherapy is not indicated, then a single platinum agent should be considered. Carboplatin has demonstrated efficacy across trials and has a manageable toxicity profile.
If a single platinum agent is not being considered, then monotherapy with paclitaxel, topotecan, or pegylated liposomal doxorubicin are seen as reasonable treatment options.
Some patients may be repeatedly sensitive to treatment and may benefit from multiple lines of chemotherapy.
For patients with platinum-refractory or platinum-resistant disease, the goals of treatment should be to improve quality of life by extending the symptom-free interval, by reducing symptom intensity, and by increasing progression-free interval, and, if possible, to prolong life.
With non-platinum agents, monotherapy should be considered because no advantage appears to accrue to the use of non-platinum-containing combination chemotherapy in this group of patients. Single-agent paclitaxel, topotecan, or pegylated liposomal doxorubicin have demonstrated activity in this patient population and are reasonable treatment options.
No evidence either supports or refutes the use of more than one line of chemotherapy in patients with platinum-refractory or platinum-resistant recurrence. Many treatment options have shown modest response rates, but their benefits over best supportive care have not been studied in clinical trials.