Melissa L. Mao, MD

Medicare activity in 2024

Official CMS public-use data for Melissa L. Mao, data year 2024 (released May 21, 2026). It covers Original Medicare (fee-for-service) patients only, not Medicare Advantage or other insurance. It shows volume, not quality or outcomes. CMS hides any count of 10 or fewer patients.

Most frequent services

1. Established patient office or other outpatient visit with low level od decision making, if using time, 20 minutes or more (99213)48 services
2. New patient office or other outpatient visit with low level of medical decision making, if using time, 30 minutes or more (99203)30 services
3. Telephone medical discussion with physician, 5-10 minutes (99441)29 services
4. New patient office or other outpatient visit with moderate level of medical decision making, if using time, 45 minutes or more (99204)13 services
5. Telephone medical discussion with physician, 11-20 minutes (99442)12 services

Chronic conditions among these patients

Share of this clinician’s Original Medicare patients with each condition, as published by CMS (it describes the patients, not the care given).

• High cholesterol75%
• High blood pressure71%
• Arthritis51%
• Chronic kidney disease41%
• Diabetes36%
• Cancer (breast, colorectal, lung, prostate, endometrial or leukemia/lymphoma)32%

Hospitals where Melissa L. Mao works

Medicare's Facility Affiliation Data lists Melissa L. Mao at these hospitals (updated October 2, 2026). Each hospital page shows its address, phone, emergency services, Medicare rating and all its clinicians. Star rating and emergency services: Hospital General Information (CMS), data updated October 26, 2026.

• UCI Health-OrangeOrange, CA · Acute Care Hospital · Medicare rating: 4 of 5 stars · Emergency services: listed by Medicare · CCN 050348

Practice locations

Addresses where Melissa L. Mao is enrolled with Medicare (CMS data updated October 2, 2026).

• 101 the City Dr SOrange, CA 92868 (714) 634‑5549

Group practices

Medicare enrollment lists Melissa L. Mao as a member of this group (CMS data updated October 2, 2026).

• University Surgeons of Orange a Medical Group116 clinicians in the group

Specialties

• Surgical Oncologyprimary

Find other Surgical Oncology doctors in California →

Other surgical oncologists in Orange

Clinicians with the same Medicare primary specialty in Orange, CA — not a recommendation.

• Oliver S. Eng, MD
• Michael P. O Leary, MD
• Kari J. Kansal, MD
• Thuy Tran, MD
• Maheswari Senthil, MD
• Alexandra G. Lopez-Aguiar, MD
• Shawndeep S. Tung, MD
• Valentina Bonev

All surgical oncologists in Orange →

Other clinicians in University Surgeons of Orange a Medical Group

Medicare enrollment lists these clinicians in the same group practice — not a recommendation.

• Marcelo W. Hinojosa, MD
• Reina N. Kim, NP
• Ashley L. Kim, NP
• Sebastian D. Schubl, MD
• Jacob M. Kirkorowicz, MD
• Sigrid Burruss, MD

Clinician information

Most corrections must be made at the source: clinicians update their NPI Registry record (NPPES) and their Medicare enrollment (PECOS); this page follows the next data release.

Sources

1. Facility Affiliation Data — Centers for Medicare & Medicaid Services (CMS), data updated October 2, 2026, retrieved October 29, 2026
2. Hospital General Information — CMS, data updated October 26, 2026, retrieved November 13, 2026
3. National Downloadable File (Doctors and Clinicians) — CMS, data updated October 2, 2026, retrieved October 29, 2026
4. Medicare Physician & Other Practitioners - by Provider — CMS, data year 2024, released May 21, 2026; Medicare Physician & Other Practitioners - by Provider and Service
5. NPI Registry — U.S. Department of Health and Human Services (NPPES), the clinician’s official record
6. Medicare Care Compare — official Medicare tool to look up clinicians