[Purpose] The present study, called the “efficacy and safety of the deodorAnt Pad against Odor and uLceration for LOcally advanced breast cancer (APOLLO)” study, aimed to assess the safety and efficacy of wearing a deodorant pad in patients with locally advanced breast cancer (LABC) with an ulceration.. [Methods] Komagome Pads for LABC, previously developed by Juntendo University and Kao Corporation, were used. In Test A, a conventional pad consisting of gauze, a commercially available diaper, pad, etc. and the Komagome Pad (not directly applied to the wound but used through a gauze, etc.) were compared over three days to assess their efficacy and possible improvements for short-term use. In Test B, the Komagome Pad was used continuously for one month to evaluate its safety during long-term use. [Results] The present study included 14 patients in Test A and nine patients in Test B. In odor evaluation using sensory testing in Test A, nine of the 14 patients reported more significant efficacy in odor suppression with the Komagome Pad than with the conventional pad. The odor intensity of the Komagome Pad was lower than that of the conventional pad on the gas chromatography mass spectrometry. The group with a high level of exudation reported significantly higher satisfaction with the Komagome Pad. In Test B, no adverse events were observed during in the clinical use of the Komagome pads. [Conclusion] Testing of a new treatment pad for LABC demonstrated that was highly safe and efficacious in suppressing odor.