Here is the design of a clinical trial:

Official Title: Docosahexaenoic Acid (DHA) for Women With Breast Cancer in the Neoadjuvant Setting

Included conditions:
- Breast Cancer

Study Armgroups:
- {'label': 'DHA', 'type': 'EXPERIMENTAL', 'description': 'Participants will take 11 capsules per day containing DHA-enriched triglyceride oil (1 g capsules containing at least 400 mg DHA) for a total of 5 g DHA/day divided into three times daily with meals or as tolerated.', 'interventionNames': ['Dietary Supplement: Docosahexaenoic acid (DHA)']}
- {'label': 'Placebo', 'type': 'PLACEBO_COMPARATOR', 'description': 'Participants will take 11 capsules per day containing corn/soy oil blend capsules divided into three times daily with meals or as tolerated.', 'interventionNames': ['Drug: Placebo oral capsule']}

Interventions:
- {'type': 'DIETARY_SUPPLEMENT', 'name': 'Docosahexaenoic acid (DHA)', 'description': 'Participants will take 11 capsules of DHA oil for 12-18 weeks (84-126 days), beginning on day 1 of initial cycle of chemotherapy, and continuing for 4-6 cycles of chemotherapy prior to definitive breast surgery. Study will end when subject undergoes breast surgery.', 'armGroupLabels': ['DHA']}
- {'type': 'DRUG', 'name': 'Placebo oral capsule', 'description': 'Participants will take 11 capsules of placebo (corn/soy oil blend) for 12-18 weeks (84-126 days), beginning on day 1 of initial cycle of chemotherapy, and continuing for 4-6 cycles of chemotherapy prior to definitive breast surgery. Study will end when subject undergoes breast surgery.', 'armGroupLabels': ['Placebo']}

Primary Outcomes:
- {'measure': 'Percent change in Ki67 index from baseline to surgical excision.', 'description': 'Ki67 will be measured by image analysis at baseline biopsy and at experimental end (surgical excision).', 'timeFrame': 'Pre-intervention (on the baseline biopsy) and post- intervention (at the time of surgical excision).'}

Please estimate the sample size based on the assumption: 
The study uses a two-sided t-test with a significance level of 0.05 (achieved 0.0497) and 81% power. The dropout rate is estimated at approximately 10%.
Sample size
        Fifty-two women prescribed neoadjuvant breast cancer chemotherapy will be enrolled in a two-arm trial with 26 participants per arm. The sample size calculation is based on the primary objective, which is to determine the efficacy of supplemental DHA provided with standard neoadjuvant as measured by change in the Ki67 index from biopsy to surgical excision. Group sample sizes of 23 patients in each group are required to achieve 81% power to detect a difference between the group proportions of 0.4. The proportion in group 1 is assumed to be 0.3 under the null hypothesis and 0.7 under the alternate hypothesis. The proportion in group 2, which is the control group, is 0.3. The test statistic used is the two-sided t-test. The significance level of the test was targeted at 0.05, and the significance level actually achieved by this design is about 0.0497. Assuming a dropout rate estimated at approximately 10% for this patient population, which is approximately 5 patients, a total of 52 patients (26 patients in the DHA supplementation group and 26 in the placebo group) are required for the study.