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 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. Stephen Sherwin, M.D.San Francisco, CA · $875,572 in drug and device payments (2025) ·
(415) 476-4082 Dr. Steven Deeks, MDSan Francisco, CA · $5,115 in drug and device payments (2025) ·
(415) 476-9362 Dr. Thierry Jahan, MDSan Francisco, CA · No drug or device payments recorded (2025) ·
(415) 353-9888 Dr. Trever Bivona, M.D., PH.D.San Francisco, CA · $3,476 in drug and device payments (2025) ·
(415) 353-7160 Dr. Varun Monga, MBBS, MDSan Francisco, CA · $123 in drug and device payments (2025) · Telehealth ·
(415) 353-7151 Dr. Wei Wang, MD, PHDSan Francisco, CA · $2,029 in drug and device payments (2025) · Telehealth ·
(415) 885-8600 Dr. Weiyun Ai, MDSan Francisco, CA · $5,038 in drug and device payments (2025) · Telehealth ·
(415) 353-2737 Dr. Wolfgang Korn, MDSan Francisco, CA · No drug or device payments recorded (2025) ·
(415) 502-4444 Dr. Xiaolin Zhu, M.D., PH.D.San Francisco, CA · $63 in drug and device payments (2025) · Telehealth ·
(415) 476-4616 Dr. Jieying Liu, MDSan Gabriel, CA · $1,318 in drug and device payments (2025) ·
(162) 665-2743 Dr. Philip Chatham, M.D.San Gabriel, CA · No drug or device payments recorded (2025) ·
(626) 652-7433 Dr. Alexander Pham, M.D.San Jose, CA · $224 in drug and device payments (2025) · Telehealth ·
(408) 426-4900 Dr. Asmita AhujaSan Jose, CA · $121 in drug and device payments (2025) · Telehealth ·
(408) 885-5000 Dr. Elwyn Cabebe, MDSan Jose, CA · $543 in drug and device payments (2025) · Telehealth ·
(408) 426-4900 Dr. George Labban, M.D.San Jose, CA · No drug or device payments recorded (2025) · Telehealth ·
(408) 426-4900 Dr. Hinda Boutrid, MDSan Jose, CA · $18 in drug and device payments (2025) · Telehealth ·
(408) 426-4900 Dr. Martha Man, MDSan Jose, CA · $29 in drug and device payments (2025) · Telehealth ·
(408) 426-4900 Dr. Peter Galatin, M.D., PH.D.San Jose, CA · $509 in drug and device payments (2025) · Telehealth ·
(408) 357-1060 Dr. Priya Kumaravelu, MDSan Jose, CA · $2,216 in drug and device payments (2025) · Telehealth ·
(650) 498-6000 Dr. Rajeshwari Ayyar, MDSan Jose, CA · No drug or device payments recorded (2025) ·
(408) 426-4900 Dr. Teja Bedi, MDSan Jose, CA · No drug or device payments recorded (2025) ·
(650) 498-6000 Dr. Thomas Chen, MDSan Jose, CA · $271 in drug and device payments (2025) · Telehealth ·
(408) 426-4900 Dr. Thomas Spillane, MDSan Luis Obispo, CA · $7,854 in drug and device payments (2025) · Telehealth ·
(805) 543-5577 Dr. Edward Mcclay, M.D.San Marcos, CA · $27 in drug and device payments (2025) ·
(760) 747-8935 Dr. John Siebel, M.D.San Mateo, CA · No drug or device payments recorded (2025) ·
(650) 341-9131 Dr. Matthew Lee, D.O.San Mateo, CA · $267 in drug and device payments (2025) · Telehealth ·
(650) 341-9131 Dr. Ryan ChangSan Mateo, CA · $89 in drug and device payments (2025) ·
(415) 514-7520 Dr. Daniel Greenwald, M.D.Santa Barbara, CA · $323 in drug and device payments (2025) · Telehealth ·
(805) 563-0041 Dr. Juliet Penn, M.D.Santa Barbara, CA · $82 in drug and device payments (2025) · Telehealth ·
(805) 563-0041 Dr. Mukul Gupta, M.D.Santa Barbara, CA · $372 in drug and device payments (2025) · Telehealth ·
(805) 879-0670 Dr. Andrea Edwards, MDSanta Cruz, CA · $1,239 in drug and device payments (2025) ·
(831) 475-8002 Dr. Michael Alexander, MDSanta Cruz, CA · No drug or device payments recorded (2025) ·
(831) 475-2220 Dr. Brent Cham, MDSanta Maria, CA · $1,169 in drug and device payments (2025) ·
(805) 349-9393 Dr. Kim Margolin, MDSanta Monica, CA · $16,304 in drug and device payments (2025) · Telehealth ·
(310) 829-8317 Dr. Przemyslaw Twardowski, MDSanta Monica, CA · $142,365 in drug and device payments (2025) · Telehealth ·
(310) 582-7137 Dr. Robert Lehrer, M.D.Santa Monica, CA · No drug or device payments recorded (2025) ·
(310) 828-0692 Dr. Fan Zhang, MDSanta Rosa, CA · No drug or device payments recorded (2025) · Telehealth ·
(707) 571-4000 Dr. Sara Keck, MDSanta Rosa, CA · $48 in drug and device payments (2025) · Telehealth ·
(707) 528-1050 Dr. Wes Lee, M.D.Santa Rosa, CA · $883 in drug and device payments (2025) · Telehealth ·
(707) 528-1050 Dr. Melissa Cohen, M.D.Simi Valley, CA · $2,375 in drug and device payments (2025) · Telehealth ·
(805) 583-0110 Dr. Elwyn Loh, M.D.South San Francisco, CA · No drug or device payments recorded (2025) ·
(650) 244-2868 Dr. Jakob Dupont, MDSouth San Francisco, CA · No drug or device payments recorded (2025) ·
(650) 255-9183 Dr. Mark Benyunes, M.D.South San Francisco, CA · No drug or device payments recorded (2025) ·
(650) 225-1628 Dr. Melissa Brammer, M.D., M.P.H.South San Francisco, CA · No drug or device payments recorded (2025) ·
(650) 467-7700 Dr. Slawomir Wojtowicz-praga, M.D.South San Francisco, CA · No drug or device payments recorded (2025) ·
(650) 467-9092 Dr. Ali Khaki, MDStanford, CA · No drug or device payments recorded (2025) · Telehealth ·
(650) 723-4000 Dr. Allison Betof, MD, PHD, FASCOStanford, CA · $21,064 in drug and device payments (2025) · Telehealth ·
(650) 723-4000 Dr. Allison Kurian, M.D.Stanford, CA · $124 in drug and device payments (2025) · Telehealth ·
(650) 723-4000 Dr. Allyson Spence, MD, PHDStanford, CA · No drug or device payments recorded (2025) · Telehealth ·
(650) 723-4000 Dr. Amina Chaudhry, MDStanford, CA · $253 in drug and device payments (2025) · Telehealth ·
(650) 723-4000 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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