Assistant Professor, Department of Surgical Oncology
Neuroendocrine Tumors, Sarcoma, Colorectal Cancer, Melanoma, Pancreatic Cyst, Liver, Gall Bladder & Bile Duct Cancer, Pancreatic Cancer, Stomach (Gastric) Cancer, GIST (Gastrointestinal Stromal Tumor)
Cancers of the liver, gall bladder, bile ducts, and pancreas; Colorectal liver metastases; Hepatic atery infusion pump chemotherapy; Robotic surgery; Minimally invasive surgery
I’m honored to be part of the talented team at Fox Chase Cancer Center. As a surgeon with specialty training in both Surgical Oncology and Hepato-Pancreato-Biliary surgery, I am focused on caring for people with benign, pre-cancerous, and malignant (cancerous) diseases of the liver, gallbladder, bile ducts, and pancreas, as well as cancers that have spread to the liver from the colon.
I completed medical school and general surgery residency at Vanderbilt University Medical Center in Nashville, Tennessee. During residency I completed a two-year research fellowship studying therapeutic resistance in pancreatic cancer, and I spent an additional two years completing a MS in Biomedical Informatics. The skills I gained during these research fellowships have been useful in almost every task I encounter, whether they are administrative, clinical, or research oriented.
My clinical training in Surgical Oncology was completed at Memorial Sloan Kettering Cancer Center. In addition to training in the full breadth of surgical oncology, I spent my final year of training specifically focused on diseases of the liver, gallbladder, bile ducts, and pancreas. This involved extensive training in robotic and laparoscopic approaches to remove tumors of the liver and pancreas, placement of hepatic artery infusion chemotherapy pumps for the treatment of colorectal liver metastases and intrahepatic cholangiocarcinoma, and the use of heat (ablation) and electricity (irreversible electroporation) to treat colorectal liver metastases.
The most formative training I received, however, has been helping family members through cancer treatment. My priority is to help you and your family members through each stage of treatment with the same level of diligence, compassion and honesty that I would give to my own family. I chose to practice at Fox Chase not only because it is a storied institution with dedicated specialists providing the highest quality of care, but also because of the profound sense of camaraderie, team work, and institutional pride evident in every interaction here.
My wife Leslie and I are very proactive about our health, which is how I discovered I had bile duct cancer. About a decade ago, my older brother was diagnosed with prostate cancer and later developed issues with his bladder as well. My prostate-specific antigen levels have always been low, but when my brother got cancer, it made me nervous because I knew it could be genetic and run in the family.
When COVID-19 hit, I decided it was time to retire from a lifetime of teaching art and do more traveling with my partner Joe. We purchased a tiny trailer and spent a year and a half visiting family and scenic vistas. Our travels were put on hold, however, when I was diagnosed with not one but two cancers.
I was a patient at Fox Chase Cancer Center and ended up spending almost 20 days in the hospital. But thankfully, it turned out that I did not have cancer, that the growth that my doctors detected was benign.
It all started in October of 2021. I was having stomach problems—diarrhea that went on for about a week. I hadn’t eaten in days, and I’d lost about 10 pounds. I’m the kind of guy that doesn’t like going to the doctor, but finally my wife and my adult son told me, “You’re going to the ER.”
Before my cancer diagnosis, I’d had stomachaches on and off for years. My husband and I work as landscapers in the summer, and I always felt good during those months. It was when we’d stop working in the winter that I’d start to feel unwell.
Dosch, Austin R., Xizi Dai, Alexander A. Gaidarski Iii, Chanjuan Shi, Jason A. Castellanos, Michael N. VanSaun, Nipun B. Merchant, and Nagaraj S. Nagathihalli. “Src Kinase Inhibition Restores E-Cadherin Expression in Dasatinib-Sensitive Pancreatic Cancer Cells.” Oncotarget 10, no. 10 (February 1, 2019): 1056–69. https://doi.org/10.18632/oncotarget.26621. PMID: 30800218.
Totiger, Tulasigeri M., Supriya Srinivasan, Venkatakrishna R. Jala, Purushottam Lamichhane, Austin R. Dosch, Alexander A. Gaidarski, Chandrashekhar Joshi, Shobith Rangappa, Jason A. Castellanos, Praveen Vemula, Xi Chen, Deukwoo Kwon, Nilesh Kashikar, Michael VanSaun, Nipun Merchant, and Nagaraj Nagathihalli. “Urolithin A, a Novel Natural Compound to Target PI3K/AKT/MTOR Pathway in Pancreatic Cancer.” Molecular Cancer Therapeutics 18, no. 2 (February 1, 2019): 301–11. https://doi.org/10.1158/1535-7163.MCT-18-0464. PMID: 30404927.
Srinivasan, Supriya, Tulasigeri Totiger, Chanjuan Shi, Jason A. Castellanos, Purushottam Lamichhane, Austin R. Dosch, Fanuel Messaggio, et al. “Tobacco Carcinogen-Induced Production of GM-CSF Activates CREB to Promote Pancreatic Cancer.” Cancer Research 78, no. 21 (November 1, 2018): 6146–58. https://doi.org/10.1158/0008-5472.CAN-180579. PMID: 30232221.
Nagathihalli, Nagaraj S., Jason A. Castellanos, Purushottam Lamichhane, Fanuel Messaggio, Chanjuan Shi, Xizi Dai, Priyamvada Rai, Xi Chen, Michael N. VanSaun, and Nipun B. Merchant. “Inverse Correlation of STAT3 and MEK Signaling Mediates Resistance to RAS Pathway Inhibition in Pancreatic Cancer.” Cancer Research 78, no. 21 (November 1, 2018): 6235–46. https://doi.org/10.1158/0008-5472.CAN-18-0634. PMID: 30154150.
Messaggio, Fanuel, Alisha M. Mendonsa, Jason A. Castellanos, Nagaraj S. Nagathihalli, Lee Gorden, Nipun B. Merchant, and Michael N. VanSaun. “Adiponectin Receptor Agonists Inhibit Leptin Induced PSTAT3 and in Vivo Pancreatic Tumor Growth.” Oncotarget 8, no. 49 (October 17, 2017): 85378–91. https://doi.org/10.18632/oncotarget.19905. PMID: 29156726.
Kummerow Broman, Kristy, Christianne L. Roumie, Melissa K. Stewart, Jason A. Castellanos, John L. Tarpley, Robert S. Dittus, and Richard A. Pierce. “Implementation of a Telephone Postoperative Clinic in an Integrated Health System.” Journal of the American College of Surgeons 223, no. 4 (2016): 644–51. https://doi.org/10.1016/j.jamcollsurg.2016.07.010. PMID: 2754510.
Nagathihalli, Nagaraj S., Jason A. Castellanos, Michael N. VanSaun, Xizi Dai, Mahogany Ambrose, Qiaozhi Guo, Yanhua Xiong, and Nipun B. Merchant. “Pancreatic Stellate Cell Secreted IL-6 Stimulates STAT3 Dependent Invasiveness of Pancreatic Intraepithelial Neoplasia and Cancer Cells.” Oncotarget 7, no. 40 (October 4, 2016): 65982–92. https://doi.org/10.18632/oncotarget.11786. PMID: 27602757.
Walsh, Alex J., Jason A. Castellanos, Nagaraj S. Nagathihalli, Nipun B. Merchant, and Melissa C. Skala. “Optical Imaging of Drug-Induced Metabolism Changes in Murine and Human Pancreatic Cancer Organoids Reveals Heterogeneous Drug Response.” Pancreas 45, no. 6 (2016): 863–69. https://doi.org/10.1097/MPA.0000000000000543. PMID: 26495796.
Nagathihalli, Nagaraj S.*, Jason A. Castellanos*, Chanjuan Shi, Yugandhar Beesetty, Michelle L. Reyzer, Richard Caprioli, Xi Chen, et al. “Signal Transducer and Activator of Transcription 3, Mediated Remodeling of the Tumor Microenvironment Results in Enhanced Tumor Drug Delivery in a Mouse Model of Pancreatic Cancer.” Gastroenterology 149, no. 7 (December 2015): 1932-1943.e9. https://doi.org/10.1053/j.gastro.2015.07.058. PMID: 26255562. *Co-first authors.
Guo Q, Ambrose M, Yugandhar Beesetty, Jason A. Castellanos, Nagaraj Nagathihalli, Nipun Merchant. IL-6 secreted from pancreatic stellate cells activates STAT3 and promotes cell growth and invasive ability of pancreatic cancer. Young Scientist. 2014; 4:63-65.
Castellanos, Jason A., and Nipun B. Merchant. “Intensity of Follow-up after Pancreatic Cancer Resection.” Annals of Surgical Oncology 21, no. 3 (March 2014): 747–51. https://doi.org/10.1245/s10434-013-3289-7. PMID: 24092447.
Castellanos, Jason A., Christina M. Edwards, Aaron Shaver, Nipun B. Merchant, and Alexander A. Parikh. “Appendiceal Adenocarcinoma Presenting as Venous Thromboembolism: An Unusual Presentation of a Rare Carcinoma.” The American Surgeon 76, no. 5 (May 2010): 543–44. PMID: 20506889.
Merchant, Nipun B., Jennifer Rymer, Elizabeth A. S. Koehler, G. Daniel Ayers, Jason A. Castellanos, David A. Kooby, Sharon H. Weber, et al. “Adjuvant Chemoradiation Therapy for Pancreatic Adenocarcinoma: Who Really Benefits?” Journal of the American College of Surgeons 208, no. 5 (May 2009): 829–38; discussion 838-841. https://doi.org/10.1016/j.jamcollsurg.2008.12.020. PMID: 19476845.
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