Antibodies, Monoclonal, HumanizedExanthemaStevens-Johnson Syndrome
John Ross Clark
NPI1871550244
- Medicare services, 2023
- 45
- Part D claims, 2024
- 54
- Publications
- 20
- Clinical trials
- 1
- Industry payments
- $47,360
- Practice address
- 55 Fruit Street, Boston, MA
- Practice phone
- Call (617) 726-2000
- Professional email
- Get professional email
- Personal email
- Get personal email
- Mobile number
- Get mobile number
Primary practice
Find John Clark's professional email, personal email and mobile number
Dmand AI checks each channel through healthcare-specific waterfall enrichment. See what is on file with a free account, with practice phones, licenses and affiliations.
John Ross Clark is a hematologist and oncologist in Boston, Massachusetts
John Clark practices at Massachusetts General Hospital in Boston, Massachusetts, part of Mass General Brigham.
John Clark's NPI, 1871550244, was assigned on April 28, 2006. John Clark graduated from Washington University School of Medicine in 1979. John Clark holds Massachusetts license 49154.
NPI and contact details
- NPI
- 1871550244NPI Registry (opens in a new tab)
- NPI enumeration date
- April 28, 2006
- NPI status
- Active
- Practice phone
- (617) 726-2000
- Professional email
- Get email
- Personal email
- Get email
- Mobile number
- Get number
- Sex
- Male
- Estimated age
- 73
- Medical school graduation
- 1979
Sources: NPPES NPI Registry (CMS); Dmand AI Professional Profile Data; and Dmand AI Affiliation Data
John Ross Clark practices at Massachusetts General Hospital in Boston, Massachusetts
John Clark's primary practice is Massachusetts General Hospital, at 55 Fruit Street, Boston, MA in Suffolk County. The practice phone is (617) 726-2000.
- Massachusetts General Hospital55 Fruit Street, Boston, MA · Suffolk CountyPhone(617) 726-2000
Source: Dmand AI Affiliation Data
John Ross Clark is affiliated with 2 medical groups
John Clark's primary practice is Massachusetts General Hospital in Boston, Massachusetts, part of Mass General Brigham. The medical group on file is Massachusetts General Physicians Organization (MGPO). Dmand AI also links John Clark to 1 more medical group, named with a free account.
Sources: Dmand AI Affiliation Data; and Dmand AI Org Hierarchy Data
Dmand AI tracks the EHR system at John Ross Clark's practice
Dmand AI tracks the electronic health record (EHR) system at each site where John Clark practices. Vendor and product names are available with a free account.
| Site | EHR vendor and product |
|---|---|
| Massachusetts General Hospital | Available with a free account |
| +1 medical group | Available with a free account |
Source: Dmand AI Technology Install Data
For health IT teams
See the EHR and IT leaders at every hospital where John Clark practices
Dmand AI maps EHR vendors, IT decision makers and buying committees across Mass General Brigham and 6.2K+ hospitals, with verified contacts in the same login.
John Ross Clark is one of 429 hematologists and oncologists in Massachusetts
Hematology and oncology is John Clark's primary specialty in the NPI Registry, under taxonomy code 207RH0003X. John Clark is licensed in Massachusetts.
Specialties and state licenses
- Hematology and oncology, MassachusettsPrimary
Hematologists and oncologists near John Clark
Counts of hematologists and oncologists with a Dmand AI profile, by place and practice. Each opens the list.
429hematologists and oncologists in Massachusetts224hematologists and oncologists in Boston73hematologists and oncologists at Massachusetts General Hospital
Sources: NPPES NPI Registry (CMS); Dmand AI Professional Profile Data; and Dmand AI Peer Benchmarks
John Ross Clark billed Medicare for 45 services in 2023
CMS data shows 45 Medicare services from John Clark across 2 procedure codes in 2023. Medicare paid $2,658 for them.
Medicare services, 202345
Paid by Medicare$2,658
Procedure codes2
John Clark's Medicare services by type, 2022 to 2023
- 2022
- 2023
- Office and hospital visits
- 2022: 5162023: 4591%
- Surgery
- 2022: 142023: 0100%
Where John Clark's Medicare services took place, 2023
- In an office1227%
- In a facility3373%
John Clark compared with the Massachusetts median for hematologists and oncologists, 2023
- John Clark
- Massachusetts median
- Medicare services
- 45vs 49591% below
- Part D claims
- 21vs 15186% below
Medians across 415 hematologists and oncologists in Massachusetts with Dmand AI profiles that report each measure.
John Clark's most billed Medicare procedure codes, 2023
CMS publishes codes billed for 11 or more Medicare patients. Each label is the code family; CPT descriptions are licensed by the AMA.
Need commercial claims for John Clark?
Medicare shows one payer. Book a meeting to get commercial claims data for John Clark and other hematologists and oncologists in Massachusetts.
Sources: Medicare Physician & Other Practitioners - by Provider and Service (CMS), 2024 data; and Dmand AI Peer Benchmarks
John Ross Clark's patients have a median age of 72
Across all payers, Dmand AI patient panel data puts John Clark's median patient age at 72, with 35% women.
John Clark's patients across all payers
Dmand AI patient panel data covers Medicare, Medicaid and commercial patients.
Patient panel by age, all payers
Median age 72
Patient panel by sex, all payers
- Women35%
- Men65%
Source: Dmand AI Patient Panel Data
John Ross Clark wrote 54 Medicare Part D claims in 2024
In 2024, John Clark wrote 54 Medicare Part D claims for 13 patients. 67% of them were for generic drugs. CMS names the drug for 21 of them, across 1 drug with 11 or more claims each, at $501,810 in total drug cost. In 2022, CMS named 35 claims across 2 drugs.
Part D claims, 202454
Drugs named by CMS1
Total drug cost$501,810
Part D patients13
John Clark's Part D claims by kind of drug, 2024
- Generic36 claims67%
- Brand-name18 claims33%
John Clark's most prescribed drugs by claims, 2023
CMS names a drug when it has 11 or more claims. Share is of the claims for drugs CMS names.
Part D claims for drugs CMS names, 2022 to 2023
- 2022
- 2023
- Claims for drugs CMS names
- 2022: 352023: 2140%
Drugs named by CMS: 1 in 2023, 2 in 2022.
Sources: Medicare Part D Prescribers - by Provider and Drug (CMS), 2024 data, released May 6, 2026; and Medicare Part D Prescribers - by Provider (CMS), 2024 data
For MedTech and pharma teams
Find hematologists and oncologists like John Clark by procedure volume and prescribing
Filter 7.4M+ HCPs by Medicare procedures, Part D drugs and Open Payments history, then reach them with verified contacts in one login.
John Ross Clark has 20 publications on record
Dmand AI links 20 papers to John Clark, published from 2010 to 2023. 2021 was the busiest year, with 4. The most frequent topics are Carcinoma, Squamous Cell, Head and Neck Neoplasms and Neoplasm Metastasis. John Clark has published most often in Oral Oncol. John Clark's most frequent co-authors are Daniel G. Deschler, MD, Lori J. Wirth, MD and Paul Martin Busse, MD, PhD.
Papers20
Years published2010 to 2023
John Clark's papers by year, 2010 to 2023
Topics John Clark writes about most
- Carcinoma, Squamous Cell
- Head and Neck Neoplasms
- Neoplasm Metastasis
- Oropharyngeal Neoplasms
- Papillomaviridae
- Squamous Cell Carcinoma of Head and Neck
- Antineoplastic Combined Chemotherapy Protocols
- Coronary Vasospasm
John Clark's most frequent co-authors
- Daniel G. Deschler, MD6 shared papers
- Lori J. Wirth, MD6 shared papers
- Paul Martin Busse, MD, PhD4 shared papers
Recent publications by John Clark
Calcium Channel BlockersCoronary VasospasmFluorouracil
AlphapapillomavirusCirculating Tumor DNAHead and Neck Neoplasms
Clin Cancer Res
Biopsy, Fine-NeedleTumor Microenvironment
See who John Clark researches with
Physician Network Discovery turns co-authorship, shared hospitals and shared groups into a map of who John Clark works with, so you can find a warm path to the right hematologists and oncologists.
Sources: PubMed (National Library of Medicine); and Dmand AI Research Linkage
John Ross Clark has worked on 1 clinical trial
Dmand AI links John Clark to 1 clinical trial. Open Payments lists research payments to John Clark that name 1 trial.
Investigators on the most trials with John Clark
- Mark Huberman, MD1 shared trial
- Conrad Wittram, MBCHB1 shared trial
Recent clinical trials with John Clark
$42,300 in research paymentsIpilimumab
Sources: Open Payments (CMS), 2025 data, released July 7, 2026; Dmand AI Research Linkage; and ClinicalTrials.gov (National Library of Medicine)
John Ross Clark received $47,360 in industry payments from 2017 to 2024
CMS Open Payments shows 21 general payments to John Clark from 2 drug and device companies from 2017 to 2024. Consulting fees make up the largest share, 100% of the total. Merck Sharp & Dohme Corporation paid the most, $47,200. It also lists 8 research payments totaling $73,000 from 2016 to 2018, naming 1 clinical trial.
General payments to John Clark by program year, 2017 to 2024
General payments to John Clark by kind, 2017 to 2024
$47.4Kin total
- Consulting fees$47,200100%
- Food and beverage$1600%
Companies that paid John Clark the most, 2017 to 2024
Share is of all general payments to this clinician.
Source: Open Payments (CMS), 2025 data, released July 7, 2026
John Ross Clark graduated from Washington University School of Medicine
John Clark graduated from Washington University School of Medicine in 1979.
- Medical school
Source: Dmand AI Professional Profile Data
Sources for John Ross Clark's profile data
| Data on this page | Source |
|---|---|
| NPI, name, sex, specialty and licenses | NPPES NPI Registry (CMS) (opens in a new tab)Dmand AI Professional Profile Data |
| Practice locations and phone | Dmand AI Affiliation Data |
| Primary practice, affiliations and health system | Dmand AI Affiliation DataDmand AI Org Hierarchy Data |
| Medicare services and procedure codes | Medicare Physician & Other Practitioners - by Provider and Service (CMS) (opens in a new tab) |
| State medians for the same specialty | Dmand AI Peer Benchmarks |
| Medicare patients and the all-payer patient panel | Dmand AI Patient Panel Data |
| Part D prescribing | Medicare Part D Prescribers - by Provider and Drug (CMS) (opens in a new tab)Medicare Part D Prescribers - by Provider (CMS) (opens in a new tab) |
| Publications, topics and co-authors | PubMed (National Library of Medicine) (opens in a new tab)Dmand AI Research Linkage |
| Clinical trials and co-investigators | Dmand AI Research LinkageClinicalTrials.gov (National Library of Medicine) (opens in a new tab) |
| Industry payments | Open Payments (CMS) (opens in a new tab) |
| Training, board certification and memberships | Dmand AI Professional Profile Data |
| EHR at each practice site | Dmand AI Technology Install Data |
| Similar physicians | Dmand AI Affiliation Data |
Data last refreshed October 2026Report an inaccuracyRemove my information
FAQ
Frequently asked questions about John Ross Clark
Spotted something out of date? Email hello@dmand.ai and we will check the record. Contact details live in the free trial.
What is John Ross Clark's NPI number?
John Ross Clark's NPI number is 1871550244. It was assigned on April 28, 2006, and it is active in the NPI Registry.
What does John Ross Clark specialize in?
John Ross Clark is a hematologist and oncologist in Boston, Massachusetts. The primary specialty in the NPI Registry is Hematology & Oncology Physician (taxonomy code 207RH0003X).
Where does John Ross Clark practice?
John Clark practices at 55 Fruit Street, Boston, MA. John Clark's primary practice is Massachusetts General Hospital in Boston, Massachusetts, part of Mass General Brigham. Dmand AI also links John Clark to 1 medical group.
What is John Ross Clark's office phone number?
The practice phone on file for John Clark is (617) 726-2000.
What is John Ross Clark's medical license number?
John Clark holds Massachusetts license 49154.
Which hospitals is John Ross Clark affiliated with?
John Clark practices at Massachusetts General Hospital in Boston, Massachusetts.
What medical group is John Ross Clark part of?
John Clark is linked to Massachusetts General Physicians Organization (MGPO). Dmand AI links John Clark to 1 more medical group.
Does John Ross Clark accept Medicare?
Yes. CMS data shows John Clark billed Medicare for 45 services in 2023.
What services does John Ross Clark bill to Medicare?
In 2023, John Clark's most billed Medicare services were office visit, established patient (99214) and care management and other visits (99443).
Where did John Ross Clark go to medical school?
John Clark graduated from Washington University School of Medicine in 1979.
Show 5 more questionsShow fewer questions
What drugs does John Ross Clark prescribe most?
In 2023 Medicare Part D data, John Clark's most prescribed drugs by claims were Lenvima.
Has John Ross Clark received payments from drug or device companies?
CMS Open Payments shows $47,360 in general payments to John Clark from 2 companies from 2017 to 2024. The largest total came from Merck Sharp & Dohme Corporation.
How long has John Ross Clark been practicing?
John Clark graduated from medical school in 1979, 47 years ago.
Does John Ross Clark do research?
Dmand AI links 20 publications to John Clark, published from 2010 to 2023. John Clark has worked on 1 clinical trial.
Who does John Ross Clark publish with?
John Clark's most frequent co-authors are Daniel G. Deschler, MD (6 shared papers), Lori J. Wirth, MD (6 shared papers) and Paul Martin Busse, MD, PhD (4 shared papers).
Selling to hematology and oncology practices?
See hematologists and oncologists in Massachusetts by site of care and group
Find the practices, groups and hospitals they work with, and the right people to contact at each.
- 30 days free
- Self-serve
- No credit card