Disclosed are a polishing composition and method of polishing a substrate. The composition has low-load (e.g., up to about 0.1 wt. %) of abrasive particles. The polishing composition also contains water and at least one anionic surfactant. In some embodiments, the abrasive particles are alpha alumina particles (e.g., coated with organic polymer). The polishing composition can be used, e.g., to polish a substrate of weak strength such as an organic polymer. An agent for oxidizing at least one of silicon and organic polymer is included in the composition in some embodiments.