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.
Where Oncologists in California practice
From CMS Medicare enrollment records covering 313 of the 450 providers listed here (70%). Providers who do not bill Medicare are not included in these figures.
7%solo or small practice (under 10 clinicians)
4%mid-size group (10 to 99)
88%large group or health system (100+)
Largest practice groups
| Group (as registered with Medicare) | Oncologists | All clinicians in group | Main city |
| Stanford Health Care | 83 | 3,152 | Stanford |
| City of Hope Medical Foundation | 38 | 964 | Duarte |
| University of California San Francisco | 33 | 1,780 | San Francisco |
| UCSF Medical Group Business Services | 31 | 1,533 | San Francisco |
| Usc Care Medical Group Inc. | 18 | 1,378 | Los Angeles |
Hospitals where they hold privileges
| Hospital | City | Ownership | CMS star rating | Oncologists affiliated |
| Stanford Health Care | Stanford | Nonprofit | 5 of 5 | 84 |
| UCSF Medical Center | San Francisco | Nonprofit | 4 of 5 | 37 |
| Stanford Health Care Tri-Valley | Pleasanton | Nonprofit | 5 of 5 | 35 |
| Keck Hospital of Usc | Los Angeles | Nonprofit | 5 of 5 | 17 |
| Cedars-Sinai Medical Center | Los Angeles | Nonprofit | 5 of 5 | 16 |
Sources: CMS Doctors and Clinicians (August 2026) and Facility Affiliation files (August 2026); hospital ownership type and overall star rating from CMS Hospital General Information (July 2026). A clinician in several groups is counted once, in the largest group they bill through. Ownership type is what the hospital reports to CMS; it does not show private equity or other investor ownership. How we build this directory.
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. Joel Lester, M.D.Anaheim, CA · No drug or device payments recorded (2025) ·
(714) 535-3660 Dr. Kambiz Afrasiabi, M.D.Anaheim, CA · $115 in drug and device payments (2025) · Telehealth ·
(714) 827-9797 Dr. Natalie Marshall, M.D.Berkeley, CA · $61 in drug and device payments (2025) · Telehealth ·
(510) 420-8000 Dr. Xin Li, M.D.Berkeley, CA · $157 in drug and device payments (2025) ·
(925) 786-9693 Dr. Charles Wiseman, M.D.Beverly Hills, CA · No drug or device payments recorded (2025) ·
(323) 377-4741 Dr. Kamlesh Sankhala, M.D.Beverly Hills, CA · $34,834 in drug and device payments (2025) · Telehealth ·
(424) 777-0708 Dr. Marina Vaysburd, M.D.Beverly Hills, CA · $65 in drug and device payments (2025) · Telehealth ·
(310) 967-1884 Dr. Noam Drazin, M.D.Beverly Hills, CA · $148,981 in drug and device payments (2025) · Telehealth ·
(310) 967-1884 Dr. Osagie Bello, M.DBrawley, CA · $3,557 in drug and device payments (2025) · Telehealth ·
(760) 351-3737 Dr. Mamatha Siricilla, M.B.B.SCameron Park, CA · $2,125 in drug and device payments (2025) · Telehealth ·
(530) 676-6600 Dr. Martin Rubenstein, MDCampbell, CA · No drug or device payments recorded (2025) ·
(408) 376-2300 Dr. Nathalie Brophy, MDCampbell, CA · No drug or device payments recorded (2025) ·
(408) 376-2300 Dr. Steven Scates, MDCampbell, CA · No drug or device payments recorded (2025) ·
(408) 376-2300 Dr. Michael Saville, MDCarlsbad, CA · No drug or device payments recorded (2025) ·
(858) 633-6632 Dr. Haroon Rehman, MDCarmichael, CA · No drug or device payments recorded (2025) · Telehealth ·
(168) 638-7509 Dr. Luko Laptalo, M.D.Carmichael, CA · $20 in drug and device payments (2025) · Telehealth ·
(916) 863-8750 Dr. Arpeet Shah, M.D.Castro Valley, CA · $19 in drug and device payments (2025) · Telehealth ·
(888) 924-1024 Dr. Byron Wilson, M.D.Castro Valley, CA · No drug or device payments recorded (2025) ·
(510) 888-0657 Dr. Ricardo Da Roza, M.D.Castro Valley, CA · No drug or device payments recorded (2025) ·
(510) 888-0657 Dr. Alex Ehsan, M.D,Cerritos, CA · $16,971 in drug and device payments (2025) · Telehealth ·
(562) 735-3226 Dr. Arlene Yu, MD, MBACerritos, CA · $5,025 in drug and device payments (2025) · Telehealth ·
(562) 735-3226 Dr. Do Young Kim, MBBSCerritos, CA · $5,829 in drug and device payments (2025) · Telehealth ·
(562) 735-3226 Dr. Nawazish Khan, MDCerritos, CA · $865 in drug and device payments (2025) ·
(562) 735-3226 Dr. Suzy Melkonian, MDChatsworth, CA · $3,134 in drug and device payments (2025) · Telehealth ·
(818) 727-0205 Dr. David Potter, MDChico, CA · No drug or device payments recorded (2025) ·
(530) 332-3890 Dr. Ranjan Pathak, M.D.Chico, CA · No drug or device payments recorded (2025) · Telehealth ·
(530) 332-4700 Dr. Kenneth Yamamoto, MDDaly City, CA · No drug or device payments recorded (2025) ·
(415) 337-2121 Dr. Steven Reich, M.D.Del Mar, CA · No drug or device payments recorded (2025) ·
(858) 755-1732 Dr. Abhishek Tripathi, M.D.Duarte, CA · $591 in drug and device payments (2025) · Telehealth ·
(626) 256-4673 Dr. Adam Rock, M.D.Duarte, CA · $1,797 in drug and device payments (2025) · Telehealth ·
(626) 256-4673 Dr. Aditya Shreenivas, MDDuarte, CA · $2,514 in drug and device payments (2025) · Telehealth ·
(626) 256-4673 Dr. Alexander Chehrazi-raffle, M.D.Duarte, CA · $12,916 in drug and device payments (2025) · Telehealth ·
(626) 256-4673 Dr. Amanda Reyes, M.D.Duarte, CA · $2,089 in drug and device payments (2025) · Telehealth ·
(800) 826-4673 Dr. Anh PhamDuarte, CA · $28 in drug and device payments (2025) · Telehealth ·
(626) 359-8111 Dr. Cathie Chung, M.D.Duarte, CA · No drug or device payments recorded (2025) ·
(626) 256-4673 Dr. Christine Lovly, MD, PHDDuarte, CA · $108,410 in drug and device payments (2025) · Telehealth ·
(626) 256-4673 Dr. Cy Stein, MDDuarte, CA · No drug or device payments recorded (2025) ·
(626) 471-3890 Dr. Daneng Li, M.D.Duarte, CA · $37,172 in drug and device payments (2025) · Telehealth ·
(626) 256-4673 Dr. Dani Castillo, MDDuarte, CA · $23,927 in drug and device payments (2025) · Telehealth ·
(626) 256-4673 Dr. Dean Lim, MDDuarte, CA · No drug or device payments recorded (2025) ·
(626) 359-8111 Dr. Erminia Massarelli, MDDuarte, CA · $21,677 in drug and device payments (2025) ·
(626) 775-3514 Dr. Hannah Chang, MDDuarte, CA · $1,532 in drug and device payments (2025) · Telehealth ·
(800) 826-4673 Dr. Howard West, MDDuarte, CA · No drug or device payments recorded (2025) ·
(626) 256-4673 Dr. James Godfrey, MDDuarte, CA · No drug or device payments recorded (2025) · Telehealth ·
(626) 256-4673 Dr. James Waisman, M.DDuarte, CA · No drug or device payments recorded (2025) ·
(626) 359-8111 Dr. Jana Portnow, MDDuarte, CA · No drug or device payments recorded (2025) · Telehealth ·
(626) 471-9200 Dr. Joanne Mortimer, M.D.Duarte, CA · $24,997 in drug and device payments (2025) · Telehealth ·
(626) 359-8111 Dr. Karen Reckamp, MDDuarte, CA · $24,576 in drug and device payments (2025) · Telehealth ·
(626) 359-8111 Dr. Lauren AntrimDuarte, CA · $221 in drug and device payments (2025) · Telehealth ·
(800) 826-4673 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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