Background: Considerable controversy exists as to whether any benefit of doxorubicin-based combination chemotherapy outweighs increased toxic effects, inconvenience, and additional costs, compared to single-agent doxorubicin. There is substantial variation in clinical practice in the treatment of patients with locally advanced and metastatic soft tissue sarcoma (STS).
Objectives: To determine:1) the effect, if any on response rate or survival, by using doxorubicin-based combination chemotherapy compared with single-agent doxorubicin for the treatment of patients with incurable locally advanced or metastatic STS2)if combination chemotherapy is associated with increased adverse effects compared with single-agent doxorubicin in this setting.
Search strategy: We searched CENTRAL (Cochrane Library, issue 4, 2002), MEDLINE (1966 to October 2002), CANCER LIT (1975 to October 2002), reference lists, the Physician Data Query (PDQ) clinical trials database, and the American Society of Clinical Oncology (ASCO) Annual Meeting Proceedings (1995 to 2002).
Selection criteria: Randomized controlled trials (RCTs) comparing single-agent doxorubicin with doxorubicin-based combination chemotherapy in adults with locally advanced or metastatic STS requiring palliative chemotherapy. Abstracts and full reports published in English were eligible.
Data collection and analysis: Data were abstracted and assessed by two reviewers. Response and survival data were pooled. Data on adverse effects was tabulated.
Main results: Data on 2281 participants from eight RCTs were available from reports of single-agent doxorubicin versus doxorubicin-based combination chemotherapy. Meta-analysis using the fixed effect model detected a higher tumour response rate with combination chemotherapy compared with single-agent chemotherapy (odds ratio [OR= 1.29; 95% confidence interval [CI], 1.03 to 1.60; p = 0.03), but the OR from a pooled analysis using the random effects model and the same data did not achieve statistical significance (OR= 1.26; 95% CI, 0.96 to 1.67; p = 0.10). No significant difference between the two regimens was detected in the pooled one-year mortality rate (OR = 0.87; 95% CI, 0.73 to 1.05; p=0.14) or two-year mortality rate (OR = 0.84; 95% CI, 0.67 to 1.06; p=0.13) (N=2097). Although reporting of adverse effects was limited and inconsistent among trials (making pooling of data for this outcome impossible), adverse effects such as nausea/vomiting and hematologic toxic effects were consistently reported as being worse with combination chemotherapy across the eight eligible studies.
Reviewer's conclusions: Compared to single-agent doxorubicin, the combination chemotherapy regimens evaluated, given in conventional doses, produced only marginal increases in response rates, at the expense of increased toxic effects and with no improvements in overall survival.