Pilot Study to Assess the Efficacy of Aspirin to Improve Immunological Features of Ovarian Tumors

Inclusion Criteria: * Participants that are greater than or equal to 18 years of age * For U.S. sites, patients can read and understand English or Spanish; for Canadian site, participants can read and understand English or French * Histology confirmed, or clinical suspicion of, invasive epithelial ovarian, fallopian tube, or peritoneal carcinoma. Must be grade 2 or 3 or high (where high is defined as grade 2/3). All histologies including serous, endometrioid, clear cell sarcoma, or carcinosarcoma histology is acceptable. Mixed histology also acceptable. * Treatment naïve for this cancer diagnosis * Planned for neoadjuvant chemotherapy (platinum-based doublet with taxane +/- anti-VEGF antibody) for at least 3 but no more than 5 cycles followed by an interval debulking surgery. \[Note: this study evaluates response while on neoadjuvant treatment. The final collection of specimen and questionnaire is at the time of surgery and immediate post-operative state. Therefore, there are no eligibility criteria related to treatment in the adjuvant setting (e.g., intraperitoneal treatment) and adjuvant therapy should proceed as the physician deems appropriate.\] * Measurable disease as defined by RECIST 1.1, CT scan (with or without contrast) within 12 weeks of study enrollment. * Eastern Cooperative Oncology Group (ECOG) performance status of 0,1, or 2 * Able to provide tissue biopsy (core or excisional) sufficient for diagnosis and biomarker analysis, may use outside archival tissue if available. * If currently using anti-coagulation medication, no contraindication for temporary stoppage of use during the study based on physician judgement * Willing and able to swallow pills without difficulty * Un-transfused platelet count \> 100,000 cells/μL * Willing and able to participate in all required evaluations and procedures in this study protocol (e.g. undergoing treatment, scheduled visits and examinations, serum testing, questionnaires, pill log/diary) * Absolute neutrophil count \> 1.5 x 109 cells/L * Hemoglobin \> 9.0 g/dL, may use transfusions and the value can be post-transfusion * Estimated creatinine clearance of \> 30 mL/min, calculated using the formula Cockcroft-Gault \[(140-age) x Mass (kg)/(72 x creatinine mg/dL)\] x 0.85 for female * No severe hepatic impairment defined as AST or ALT elevation \< 2.5 x institutional ULN, unless liver metastasis is present \< 5 x ULN Exclusion Criteria: * Definite contraindication for either aspirin use or stopping current aspirin use based on physician's clinical judgment * History of vascular event in the last 12 months (e.g., myocardial infarction or unstable angina, stroke, coronary artery angioplasty or stenting, coronary artery bypass graft, relevant \[serious or significant\] arrhythmias, significant vascular disease, congestive heart failure or vascular interventions). * History of hypertensive crisis and/ or uncontrolled HTN, systolic blood pressure \> 150 mmHg; diastolic blood pressure \> 90mmHg. Participants must have blood pressure \< 150/90 mmHg taken in a clinic setting by a medical professional within 2 weeks prior to starting study. * Current or history of ulcers which prohibits aspirin consumption, severe hepatic failure, or acute or chronic renal disease where aspirin use is contraindicated * History of gastrointestinal or genitourinary bleeding or other bleeding diathesis or coagulopathy within 6 months prior to enrollment of study * Uncontrolled erosive esophagitis requiring 2 or more treatments * Other cancer diagnosis in the last 3 years other than non-melanoma skin cancer * Autoimmune disorder requiring systemic therapy * Chronic steroid use defined as 3 weeks in the past year or any length of time in the past 30 days. * Other aspirin or NSAID hypersensitivities or contraindications (e.g. allergy) * History of bariatric surgery * Currently pregnant at the Screening visit or planning on becoming pregnant during the study period * Participant is unable to swallow orally administered medication and patients with gastrointestinal disorders likely to interfere with study medication. * Metabolism CYP2C9, known G6PD deficient patients