A SWOG/GOG phase 3 trial exploring the impact of 12-monthly cycles of paclitaxel given to patients with advanced ovarian cancer who achieved a complete response to primary chemotherapy was discontinued by the Data Safety and Monitoring Committee when a prospectively defined interim analysis revealed a highly statistically significant improvement in progression-free survival (PFS). At study closure, it was too early to assess the impact on overall survival.

Patients (n=296) received either 3 or 12 monthly cycles of paclitaxel (175 mg/m(2) over 3 h).

Of the 146 patients on the 3-cycle arm, 9 (6%) received >3 cycles. Median (12 versus 3 cycles; intention-to-treat analysis) updated PFS (all pts) 22 versus 14 months, p=0.006; overall survival (all pts) 53 versus 48 months, p=0.34.

Twelve cycles of single agent maintenance paclitaxel significantly improves PFS. Explanations for the lack of a favorable influence on overall survival include: (a) treatment at relapse equalized outcome; (b) the sample size was insufficient to reveal a difference; (c) "crossover" of patients from 3 cycles to longer treatment masked a potential difference. An ongoing phase 3 trial will hopefully provide a definitive answer to the question of the impact of this maintenance strategy on overall survival.