Locations Near You

Contact Us Today

Meet Our Physicians

Anita Tharian, D.O.

Dr. Anita Tharian is a board-certified and fellowship trained medical oncologist and licensed to practice in Texas. Dr. Tharian is Director of Hematology/Medical Oncology at Northpoint Cancer Center. Dr. Tharian specializes in the care of persons diagnosed with cancer: including lung cancer, breast cancer, mediastinal tumors, and cancer of unknown primary site.

Dr. Tharian emphasizes personalized oncology care by tailoring treatment plans to each individual patient. Dr. Tharian’s depth of experience in academic medicine and patient care means she places a high priority on using the latest technologies, research and treatment discoveries to fight cancer together with you.

Dr. Tharian’s board certifications include: American Board of Internal Medicine; American Board of Internal Medicine – Medical Oncology; American Board of Internal Medicine – Hematology.

Dr. Tharian has been practicing medicine in the Texas area for many years now and is well known in the community.

Medical Education
University of North Texas Health Science Center- Internal Medicine

University of Texas Health Science Center at San Antonio- Internal Medicine

University of Texas Health Science Center at San Antonio- Hematology and Medical Oncology

Kimberly Stewart, DO

Dr. Kimberly Stewart is a Radiation Oncologist and Medical Director at our Landmark Cancer Center locations in San Antonio, Texas and has been practicing for over 20 years.

Dr. Stewart has extensive experience with external beam radiation. She graduated from Chicago College Of Osteopathic Medicine Of Midwestern University, Midwestern University in 1997 . Dr. Stewart’s treatment philosophy is she believes that helping you fight cancer where you live and work is simply a better approach for you and your family.

Dr. Stewart is a professional member of the American Osteopathic Association, American Osteopathic College of Radiology, American Society for Radiation Oncology (ASTRO), the Radiosurgical Society, and Texas Osteopathic Medical Association.

Dr. Stewart’s Education Details

  • Chicago College Of Osteopathic Medicine Of Midwestern University, Midwestern University
    Medical School | Graduated 1997
  • Midwestern University Arizona GME Consor
    Internship Hospital | Completed 1998
  • Rehabilitation Institute of Chicago
    Residency Hospital | Completed 1998
  • William Beaumont Hospital
    Residency Hospital | Completed 2003



Dr. Thomas Nabhani M.D., Ph.D.

A radiation oncologist, Dr. Nabhani uses high-energy radiation to kill cancer cells by damaging their DNA. He has extensive research experience in oncology on topics including cancer stem cells, new diagnostic technologies, cancer epidemiology, quality of life and outcomes. His primary research interest is in quality of life and clinical predictive models in prostate radiotherapy. Dr. Nabhani is trained in a number of specialized techniques, including intensity-modulated radiation therapy, image-guided radiation therapy, stereotactic body radiation therapy, stereotactic radiosurgery, 3D conformal radiotherapy and prostate seed implant brachytherapy. He is familiar with a range of technologies and can help patients with many types of cancer.

Dr. Nabhani received his MD, PhD and BA from the University of Illinois-Chicago. He completed a residency in radiation oncology at State University of New York-Downstate in Brooklyn, N.Y. Thomas completed a fellowship in medical informatics with the Department of Radiation Oncology and Molecular Radiation Sciences at Johns Hopkins Hospital in Baltimore, Md. He also completed a fellowship in neuro-oncology with the Department of Surgery, Division of Neurosurgery at UCLA Medical Center in Los Angeles.

“Treating cancer is a challenge – there are more than 100 types of cancer, and every patient is unique,” said Dr. Nabhani. “To successfully treat the disease, I believe in patient-centered care, with a strong commitment to multidisciplinary collaboration with each member of the patient’s clinical team. I value effective open communication between patients, their families, and the clinical care team. This is the key to achieving the best results.”

When he’s not caring for patients, Dr. Nabhani enjoys spending time with his wife and their young son. He likes outdoor activities including off-roading with his truck and motorcycle, hiking, skiing and golfing. He also enjoys watching NFL football with his family.

Simeon Jaggernauth, M.D.

Scientist, Innovator, Medical Oncologist and former adjunct professor of Oklahoma State University Centers for Health Sciences, believes it’s absolutely important for patients to learn as much as they can about their illness.

Dr. Jaggernauth (aka Dr. Jag) earned his doctorate in medicine from Oklahoma State University Center for Health Sciences College of Medicine. He then completed an internship at OSU Medical Center, his internal medicine residency at the University of Oklahoma, and a subspecialty fellowship in Medical Oncology at the University of Louisville in Kentucky. Dr. Jag is an allopathic board certified Medical Oncologist and Internal Medicine physician by the American Board of Medical Specialties (ABMS). He is also board certified in Mechanical Engineering by the American Society of Mechanical Engineering (ASME). He worked in research and development prior to becoming a physician and co-invented several systems for water emulsion and solid particle detection counters for high pressure hydraulic systems used by Union Pacific Railroads® and NASA®. The co-invention of the Digital Moisture Alert® (dMA) and the Ferrous Contam Alert® (fCA) led to patents granted for both devices. U.S.Patent (#5,563,337). His Apps have been featured in the iTunes App Store® (iChemo Deluxe) for computing chemotherapy doses to help doctors with their chemotherapy dosing and to prevent medical errors in oncology.

Dr. Jag has served as principal investigator and sub investigator for multiple clinical trials on pharmaceutical agents used to treat metastatic breast, colon and lung cancers. He started the Medical Oncology Fellowship at Oklahoma State University and Cancer Treatment Centers of America. He was responsible for training doctors to become cancer fighters as Medical Oncologists. He served as the Chairman of the Cancer Committee a member of the Medical Executive Committee at CTCA. Prior to joining Landmark Cancer Center he was part of the MD Anderson Affiliated Network in Tulsa, Oklahoma. He also serves as a medical consultant on the scientific advisory board of several biotech companies including Genentech, General Electric Healthcare, Bristol-Myers Squibb, Celgene, and NovoCure. He is the Founder and Chairman of the non-profit organization, the H8 Cancer Foundation.

Dr. Jag has presented throughout the country as a speaker on new oncologic treatments available to patients. He has been published in the Journal of Clinical Oncology and Breast Cancer Wellness Magazine and has also been featured in Oklahoma Magazine, FOX, ESPN, Good Morning Texas on the Dallas ABC affiliate, and Kansas City Live. As an active leader of the community, Dr. Jag has been a guest speaker for the American Lung Association Lung Force, volunteered for the Tulsa Project Woman, and raced in the local Susan G. Komen Race for the Cure®. He was also featured in the Tulsa World with the debut of the Ken Burns film “The Emperor of All Maladies” when the PBS series aired nationwide. Dr. Jag loves spending time with his wife of over 25 years and their four children. He also enjoys playing video games with his kids, wake surfing, running, making movies with his drones, and high speed racing.

You can connect with him on Facebook by searching for @MyDoctorJAG or on Twitter @DoctorJAG.

John D. Wells, M.D.

Dr. John Wells is a medical oncologist who specializes in the care of persons diagnosed with cancer: including lung cancer, breast cancer, mediastinal tumors, and cancer of unknown primary site. Research interests include tests for new anticancer treatments, the discovery of medicines that specifically attack lung cancer, multimodality therapy (using surgery, radiotherapy, and chemotherapy together to destroy cancers), and better ways to control physical symptoms caused by cancer and cancer treatment. Dr. Wells is particularly interested in finding ways to select the best treatments for persons with cancer based on clinical factors and the molecular characteristics of their tumor specimens.

Dr. Wells is Chief Medical Oncologist at Landmark Cancer Center in Rogers, Arkansas. Dr. Wells is a graduate of The University of Arkansas School of Medicine. Residencies included Tampa General Hospital, and The University of Arkansas Medical Center. Dr. Wells is board certified in Internal Medicine, Medical Oncology, Hematology, Internal Medicine, Advanced Achievement. Dr. Wells was listed among the Best Doctors in America, Central Region, Hematology and Medical Oncology, 1996 – 1997 and 2001 – 2002.

Dr. Wells clinical expertise includes: Lung Cancer; New Cancer Treatments; Thymoma; Mediastinal Tumors; Control of Side Effects and Physical Problems Caused by Cancer and Cancer Treatments.

Ravikumar Vasireddy, M.D.

Dr. Ravikumar Vasireddy is a medical oncologist who specializes in medical oncology and hematology. Dr. Vasireddy is a board certified medical oncologist and hematologist and is licensed to practice in Ohio, Oklahoma, and Maryland. Dr. Vasireddy specializes in the care of persons diagnosed with cancer: including lung cancer, breast cancer, mediastinal tumors, and cancer of unknown primary site.

Board Certifications include: American Board of Internal Medicine; American Board of Internal Medicine – Medical Oncology; American Board of Internal Medicine – Hematology

Dr. Vasireddy’s clinical expertise includes: Lung Cancer; New Cancer Treatments; Thymoma; Mediastinal Tumors; Control of Side Effects and Physical Problems Caused by Cancer and Cancer Treatments.

Dr. Vasireddy has been practicing medicine in the Muskogee, Oklahoma area for many years now and is well known in the community. Trained in India and the United States, Dr. Vasireddy received his medical degree from Kakatiya Medical College, Kakatiya University, Warangal, India. He served his internship at MGM Hospital in Warangal and then completed residency programs in pathology and dermatology at Kakatiya Medical College and Gandhi Medical College, Hyderabad, India. He also trained in dermatology at the University of Wales, Cardiff, UK. Dr. Vasireddy worked in various medical positions and as a consultant in India before serving an internal medicine residency at Prince George’s Hospital, Cheverly, Maryland. He received his specialty training in oncology and hematology at the University of Cincinnati, Cincinnati, Ohio. Dr. Vasireddy’s memberships include The American Society of Clinical Oncology and The American Medical Association.

Dr. Vasireddy is Chief Medical Oncologist at Landmark Cancer Center in Muskogee, Oklahoma.

Joshua Garren, M.D.

Dr. Joshua Garren is an award winning, board-certified radiation oncologist, from the world-renowned Lahey Clinic in Boston where he led the radiosurgery program for over eight years.

His research career began in the Brown University MD/PhD program. His research on minimizing the side effects of radiation has been presented and supported internationally. He received his neurosurgery training at NYU Medical Center, where he worked on the first radiosurgery system in New York. Dr. Garren’s interest in health care for the disadvantaged began at the Harvard/Brown MD/MPH program. He has worked with Doctors of the World and has received a fellowship from the Albert Schweitzer Foundation.

Dr. Garren has been voted one of Boston’s top doctors by his peers in each of the past four years. Prior to joining Landmark, Dr. Garren was named to the first US News and World Report list of top doctors in the United States.

Dr. Garren speaks English, French and Russian. During his free time, he coaches his five budding young soccer stars, Daniel, Ariella, Maya, Jonathan and Shira Garren.

Gary Young, M.D.

Dr. Young wants every patient to benefit from the most aggressive options in cancer treatment through radiation therapy. His focus is on assessing each patient’s specific needs and then working with the family to create a radiation therapy plan resulting in the best possible outcome.

He is also skilled in the use of CyberKnife® Radiosurgery, a complex type of cancer treatment using precise radiation in place of surgery. This technology can be effective for treating tumors previously considered inoperable.

Dr. Young completed medical school at Oral Roberts University in Tulsa, Oklahoma. He completed an internship and residency University of California at Irvine. He had planned to specialize in medical oncology but fell in love with radiation oncology when doing an elective in that field. As a result, Dr. Young stayed at UC Irvine to complete an additional residency in radiation oncology, including experience at two prestigious facilities: the designated National Cancer Institute City of Hope Cancer Center and brachytherapy experience at Long Beach Memorial. Dr. Young also earned a Bachelor of Science degree with a double major in biochemistry and microbiology from University of California at Berkeley.  He is Board Certified in Radiation Oncology by the American Board of Radiology and Internal Medicine by the American Board of Internal Medicine.

Wilhelm Lubbe, M.D., Ph.D.

Radiation oncology is undergoing an explosion of new cutting edges techniques.  Recently spending four years at the Fox Chase Cancer Center in Philadelphia, Dr. Wilhelm Lubbe worked at a unique cancer only institution holding two Nobel Prize winners.  At this world leading cancer treatment center Dr. Lubbe has utilized some of the world’s most innovative emerging techniques. A Diplomat of the American Board of Radiology, Dr. Lubbe is a Board Certified Radiation Oncologist.  This experience affords Dr. Lubbe the luxury of knowing the full extent of the advantages and limitations of each new technology and technique.

Holding two doctoral degrees, Dr. Lubbe was awarded a prestigious medical program where he received both a M.D. and Ph.D. at the same time.  This was within a special program through Jefferson Medical College in Philadelphia.  In addition to his clinical expertise, he obtained a Ph.D. in molecular cancer research.  Beyond winning multiple awards in both medicine and cancer research, he has coauthored a United States patent for a molecular guided cancer therapy. This strategy activates the body’s own internal and environmental biomechanisms to inhibit cancer spread.  His research on natural molecular cancer treatments and innovative radiation techniques have been presented at oncology meetings drawing a world wide audience.
Outside of work, Wilhelm enjoys a great variety of activities in the Dallas area.  Of note, he was a NCAA Division I tennis player at Villanova University and received All-Conference distinctions as a pre-medical student athlete. Surprisingly, after medical school Wilhelm also became a nationally ranked USA Track and Field sprinter.  Born in West Virginia, Wilhelm Johannes Lubbe has a completely German name with a South African twist.  Lubbe, like Porsche, ends in an “e” but sounds like an “a”.  In Texas, Wil says Lubbe is pronounced like Bubba with an “L”.
Timothy D. Nichols, M.D.

Dr. Timothy Nichols is an independently practicing Radiation Oncologist at Landmark Cancer Center, he has extensive experience with external beam radiation (IMRT, IGRT, 3D Conformal), and he specializes in Stereotactic Radiosurgery and Partial Breast Irradiation. Dr. Nichols is Board Cerified in the field of Radiation Oncology by the American College of Radiology. A Dallas resident, Dr. Nichols earned his undergraduate and medical degrees from the University of Maryland in Baltimore, Maryland. He served his residency in Radiation Oncology at the University of Maryland Medical Center, as well as receiving a Fellowship from that institution. He has most recently served as Radiation Oncologist at the Presbyterian Hospital of Dallas, and earlier held the position of Medical Director at the Plano Oncology Center. He is a member of the American Society for Therapeutic Radiology and Oncology, the American College of Radiology, the American Medical Association, the Texas Medical Association and the Dallas County Medical Society.

Matthew L. Cavey, M.D.

Dr. Cavey holds a Bachelor of Science in Electrical Engineering and a Master of Science in Engineering Management from Southern Methodist University in Dallas, Texas. He earned his Doctor of Medicine at the University of Texas Medical Branch in Galveston, Texas. Dr. Cavey completed his internship at Austin Medical Education Programs at Brackenridge Hospital in Austin, Texas, and he completed his residency in Radiation Oncology at the University of Texas Medical Branch in Galveston. Dr. Cavey has been extensively involved in clinical radiation oncology research, particularly in breast and prostate cancer. He has published several articles in peer-reviewed journals and has presented at numerous national and international meetings. He was honored for his research efforts with an award from the Research and Education Foundation of the Radiological Society of North America.