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Oncologists in California

Data updated monthly · Last refresh October 2026

450 Medical Oncology providers practice in California, including 271 (60%) offering telehealth. The largest concentration is in Stanford. Profiles include federal Open Payments records of money received from drug and device companies in 2025. Listings are drawn from federal public records and are not endorsements.

450providers
271telehealth
Stanfordtop city

Medical Oncology by city in California

Choose a city to see providers there.

Medical Oncology in Stanford83 providers
Medical Oncology in San Francisco54 providers
Medical Oncology in Duarte49 providers
Medical Oncology in Los Angeles39 providers
Medical Oncology in San Diego19 providers
Medical Oncology in Palo Alto18 providers
Medical Oncology in Sacramento11 providers
Medical Oncology in San Jose11 providers
Medical Oncology in La Jolla7 providers
Medical Oncology in Pleasanton7 providers
Medical Oncology in Irvine6 providers
Medical Oncology in Orange6 providers
Medical Oncology in Redding5 providers
Medical Oncology in South San Francisco5 providers
Medical Oncology in Fullerton4 providers
Medical Oncology in Cerritos4 providers
Medical Oncology in Loma Linda4 providers
Medical Oncology in Pasadena4 providers
Medical Oncology in Beverly Hills4 providers
Medical Oncology in Fresno3 providers
Medical Oncology in Campbell3 providers
Medical Oncology in Torrance3 providers
Medical Oncology in Castro Valley3 providers
Medical Oncology in West Hollywood3 providers

Medical Oncology providers in California

Listed by city, largest first. Payment figures come from the federal Open Payments program, which requires drug and device companies to report what they pay physicians for consulting, speaking, meals, travel and royalties. A disclosed payment is a financial relationship, not evidence of wrongdoing, and many totals reflect a single meal. Figures cover calendar year 2025.

Dr. Leah Naghi, MD
Duarte, CA · $225 in drug and device payments (2025) · Telehealth · (177) 986-2578
Dr. Lee Cranmer, MD, PHD
Duarte, CA · $6,475 in drug and device payments (2025) · Telehealth · (800) 826-4673
Dr. Linda Bosserman, M.D., F.A.C.P
Duarte, CA · $1,848 in drug and device payments (2025) · Telehealth · (626) 256-4673
Dr. Louisa Liu, MD
Duarte, CA · $1,344 in drug and device payments (2025) · (800) 826-4673
Dr. Lucille Leong, MD
Duarte, CA · No drug or device payments recorded (2025) · (626) 359-8111
Dr. Manana Elia, M.D.
Duarte, CA · No drug or device payments recorded (2025) · Telehealth · (626) 256-4673
Dr. Marianna Koczywas, MD
Duarte, CA · No drug or device payments recorded (2025) · (626) 359-8111
Dr. Marwan Fakih, MD
Duarte, CA · $34,315 in drug and device payments (2025) · Telehealth · (626) 359-8111
Dr. Matthew Lee, MD
Duarte, CA · $15,881 in drug and device payments (2025) · Telehealth · (800) 826-4673
Dr. Melanie Palomares, MD
Duarte, CA · $65 in drug and device payments (2025) · (626) 359-8111
Dr. Molly Diaz, PA-C
Duarte, CA · $81 in drug and device payments (2025) · Telehealth · (626) 256-4673
Dr. Mykola Onyshchenko, MD, PHD
Duarte, CA · $149 in drug and device payments (2025) · Telehealth · (626) 256-4673
Dr. Nikhila Kethireddy, M.D.
Duarte, CA · $313 in drug and device payments (2025) · Telehealth · (626) 256-4673
Dr. Peter Zang
Duarte, CA · $218 in drug and device payments (2025) · (626) 218-7275
Dr. Ramya Muddasani, D.O.
Duarte, CA · $221 in drug and device payments (2025) · Telehealth · (626) 256-4673
Dr. Ravi Salgia, MD,PHD
Duarte, CA · No drug or device payments recorded (2025) · Telehealth · (626) 218-3712
Dr. Roberto Rodriguez, MD
Duarte, CA · $146 in drug and device payments (2025) · (626) 359-8111
Dr. Sharonlin Bhardwaj, M.D.
Duarte, CA · $255 in drug and device payments (2025) · Telehealth · (626) 256-4673
Dr. Sumanta Pal, MD
Duarte, CA · $1,010 in drug and device payments (2025) · Telehealth · (626) 359-8111
Dr. Tanya Dorff, M.D.
Duarte, CA · $18,953 in drug and device payments (2025) · Telehealth · (626) 256-4673
Dr. Thanh Nga Doan, M.D.
Duarte, CA · $245 in drug and device payments (2025) · Telehealth · (626) 256-4673
Dr. Thehang Luu, MD
Duarte, CA · No drug or device payments recorded (2025) · (626) 359-8111
Dr. Tiffany Kaul, MD, PHD
Duarte, CA · $551 in drug and device payments (2025) · (800) 826-4673
Dr. Victoria Seewaldt
Duarte, CA · $2,763 in drug and device payments (2025) · (626) 256-4673
Dr. Wenge Wang, M.D., PH.D.
Duarte, CA · $983 in drug and device payments (2025) · Telehealth · (626) 256-4673
Dr. Yan Xing, MD
Duarte, CA · $196 in drug and device payments (2025) · Telehealth · (626) 256-4673
Dr. Yun Yen, MD
Duarte, CA · No drug or device payments recorded (2025) · (626) 359-8111
Dr. Jonathan Schechter, MD
El Dorado Hills, CA · No drug or device payments recorded (2025) · (916) 933-2442
Dr. Jeffrey Klein, M.D.
Encino, CA · No drug or device payments recorded (2025) · (800) 757-4242
Dr. Muneeb Choudry, M.D.
Escondido, CA · $393 in drug and device payments (2025) · Telehealth · (760) 740-2715
Dr. Christopher Williams, M.D.
Eureka, CA · No drug or device payments recorded (2025) · (707) 267-2060
Dr. Casey Bermack, MD PHD
Foster City, CA · No drug or device payments recorded (2025) · (650) 574-3000
Dr. Ranjan Sapra, M.D.
Fountain Valley, CA · $2,553 in drug and device payments (2025) · (714) 432-7500
Dr. Ahmed Sadiq, MD
Fremont, CA · $124 in drug and device payments (2025) · (510) 796-0222
Dr. Li Ge, MD
Fresno, CA · $4,616 in drug and device payments (2025) · Telehealth · (559) 438-7390
Dr. Lucio Nobile, MD
Fresno, CA · No drug or device payments recorded (2025) · Telehealth · (559) 448-5524
Dr. Oranus Mohammadi, MD
Fresno, CA · $7,525 in drug and device payments (2025) · Telehealth · (559) 438-7390
Dr. David Park, M.D.
Fullerton, CA · $8,731 in drug and device payments (2025) · Telehealth · (714) 446-5900
Dr. Giribala Patel, M.D.
Fullerton, CA · $1,619 in drug and device payments (2025) · Telehealth · (714) 446-5900
Dr. Richard Lloyd, M.D.
Fullerton, CA · $39 in drug and device payments (2025) · (714) 446-5900
Dr. Sanjay Sharma, M.D.
Fullerton, CA · $73,881 in drug and device payments (2025) · Telehealth · (714) 449-4800
Dr. Ami Patel, M.D.
Glendale, CA · $3,419 in drug and device payments (2025) · Telehealth · (818) 543-7574
Dr. Morganna Freeman, D.O.
Glendale, CA · $80 in drug and device payments (2025) · (310) 231-2176
Dr. Raymundo Romero, M.D.
Glendale, CA · $6,171 in drug and device payments (2025) · Telehealth · (818) 543-7574
Dr. Robert Morgan, MD
Glendora, CA · No drug or device payments recorded (2025) · (626) 914-1399
Dr. Rupali Nabar, MD
Huntington Beach, CA · No drug or device payments recorded (2025) · Telehealth · (714) 378-4920
Dr. Charles Nguyen, M.D.
Irvine, CA · $6,189 in drug and device payments (2025) · Telehealth · (949) 671-4673
Dr. Elizabeth Conner, MD
Irvine, CA · $35 in drug and device payments (2025) · Telehealth · (800) 826-4673
Dr. Irene Kang, M.D.
Irvine, CA · $12,974 in drug and device payments (2025) · Telehealth · (949) 671-4673
Dr. Katarina Vasiljevic, M.D.
Irvine, CA · $150 in drug and device payments (2025) · Telehealth · (888) 333-4673

Common questions

How many Medical Oncology providers are in California?

There are 450 Medical Oncology providers with active NPI records practicing in California, according to federal NPPES data refreshed monthly.

Do Medical Oncology providers in California offer telehealth?

Yes. 271 of the 450 Medical Oncology providers in California (about 60%) report offering telehealth services in CMS data.

Which cities in California have the most Medical Oncology providers?

Stanford (83), San Francisco (54), Duarte (49) have the highest concentration of Medical Oncology providers in California.

How many Medical Oncology providers in California received drug or device company payments?

281 of 450 Medical Oncology providers in California (62%) received at least one payment from a drug or device company in 2025, according to the federal Open Payments program.

Where does this data come from?

Provider counts and profiles come from the federal NPPES registry and CMS Doctors and Clinicians files. Payment figures come from the CMS Open Payments program for calendar year 2025. The directory refreshes monthly.

Do most Oncologists in California work in independent practices or large health systems?

Among 313 Oncologists in California enrolled in Medicare, 7% bill through a solo or small practice with fewer than 10 clinicians, 4% through a mid-size group of 10 to 99, and 88% through a large group or health system with 100 or more clinicians, according to CMS enrollment records.

Which hospitals do Oncologists in California work at?

According to CMS facility affiliation records, the California hospitals where the most Oncologists hold privileges are Stanford Health Care in Stanford; UCSF Medical Center in San Francisco; Stanford Health Care Tri-Valley in Pleasanton.

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Sources: NPPES (CMS), Doctors and Clinicians national files, CMS Open Payments 2025. Updated monthly. Records are public federal data and are not verified credentials, licensure checks, or endorsements. This directory is informational and not medical advice. How we build this directory. Are you a Medical Oncology in California? Get featured.