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Medical Oncology Hematology

The June E. Nylen Cancer Center has a caring and capable medical staff, dedicated to providing personal care to their patients. Below are the biographies outlining their extensive educations, past experiences, as well as memberships in a variety of cancer-related organizations.

Donald B. Wender, MD, Ph.D.

Dr. Wender received his medical degree from Ohio State University and a Ph.D. in biochemistry from Case Western Reserve University. He completed his internship, residency and fellowship at the University of Pittsburgh Health Center. He is a member of the American College of Physicians, the Iowa Oncology Society and the American Society of Clinical Oncology. He is board-certified in medical oncology by the American Board of Internal Medicine and currently serves as principal investigator for research with participation in the Alliance Clinical Research Group sponsored by the National Cancer Institute. He also serves on the executive committee of ACCRV, a collaborative research group between industry and clinicians.

Robert W. Horowitz, MD

Dr. Horowitz received his medical degree from New York Medical College.  He completed his residency in Internal Medicine at Northshore Hospital in Manhasset, NY, and his fellowship at Montefiore Medical Center in Bronx, NY. He served as Medical Director of the Oncology Department of York Hospital in York Maine for 19 years before coming to the June E. Nylen Cancer in 2018. He is board certified in medical oncology, and has extensive experience with hospice and palliative care, serving as Medical Director of Merrimack Valley Hospice from 2012 – 2018 and Beacon Hospice from 2004 – 2012. He is a member of the American Society of Clinical Oncology, a past recipient of the ACS fellowship and Wellcome Research Awards, and has authored several articles on oncology treatments.


Nasser G. Abu-Erreish, MD

Dr. Nasser Abu-Erreish earned his medical degree from the University of Jordan in Amman Jordan. He completed his internship and residency in medical and surgical specialties at the University of Jordan Hospital and his internal medicine internship and residency at the University of Arkansas.  His fellowship program in Medical Oncology was completed at East Tennessee State University in Johnson City, TN.                     

Dr. Abu previously practiced as a Medical Oncologist at Sky Lakes Medical Center Cancer Treatment Center in Klamath Falls, Oregon, and he served as the Cancer Liaison Physician in Klamath County, OR. He is board-certified in Internal Medicine and Medical Oncology from the American Board of Internal Medicine.

Moscoso 8x10

Dr. Santiago Moscoso, MD

Dr. Santiago Moscoso earned his medical degree from Central University of Ecuador in Quito, Ecuador.  He completed his residency in Internal Medicine at Advocate Illinois Masonic Medical Center in Chicago, IL and his Fellowship in Oncology and Hematology at the Brooklyn Hospital Center.

Dr. Moscoso is board-certified in Internal Medicine, Medical Oncology, and in Hematology, all from the American Board of Internal Medicine.

Dr. Javvaji 2019

Dr. Chandana Javvaji, MD

Dr. Javvaji received her medical degree from N.R.I. Medical College, Guntur, Andhra Pradesh, India.  She completed her residency in Internal Medicine at the University of Buffalo-Catholic Health System in Buffalo, NY, and her fellowship in Hematology-Oncology at the University of Massachusetts Medical School in Worcester, MA.  Dr. Javvaji is Board Certified in Internal Medicine, Medical Oncology and Hematology.

Roth Department of Radiation Oncology

Greg Naden, MD

Dr. Naden is a native of Cedar Rapids, a graduate of the University of South Dakota and the University of Iowa Medical School, and is board-certified in Radiation Therapy. After serving his internship in Michigan and residency in California, Dr. Naden practiced in Madison, Wisconsin from 1988-2005. He is Board Certified in Radiation Oncology by the American Board of Radiology.

Vatsal B. Patel, MD, MBA

Dr. Patel was in Connecticut for several years as he received his undergrad degree from University of Connecticut of Liberal Arts and Sciences, his MBA from University of Connecticut School of Business, and his medical degree from University of Connecticut UConn Health School of Medicine. He completed his internship at Yale New Haven Hospital/Yale School of Medicine and then went on to complete his Residency at Mays Cancer Center, UT Health San Antonio MD Anderson Cancer Center.

Dr. Patel moved to Sioux City from Texas and enjoys acting and writing, bike riding and swimming.

Additional Providers

Jaclyn Hulett, ARNP

Jackie is a native of Lenox, Iowa and received her BSN and MSN as a Family Nurse Practitioner from Allen College in Waterloo, Iowa. Before joining the June E. Nylen Cancer Center she worked at UnityPoint Health as a registered nurse administering chemotherapy and before that in long-term care here in Sioux City. Jackie was inspired to explore working in health care because of her Grandma Rose who passed away from breast cancer. Jackie says her grandmother didn’t have many options and the cancer progressed to her bones. Cancer care has greatly advanced since then, but Jackie is still motivated to ensure each patient she works with understands their care plan and treatment, next steps and side effects. She hopes she can help patients lessen their anxiety and feel more comfortable in an uncomfortable situation.

In her free time, Jackie spends time with her family, which includes 4 children and enjoys gardening. She also is a big animal-lover.

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