Pathologic Complete Response After Neoadjuvant Chemoradiation in a Patient with Gastric Neuroendocrine Cancer

Abstract

Neuroendocrine tumors are about 0.5% of all malignancies. Specifically, for gastrointestinal (GI) malignancies, neuroendocrine tumor incidence is approximately 1%-2% per year. Gastric neuroendocrine neoplasms are rare and consist of various tumor types with differing histomorphology, pathogenesis, and biological behavior. Following surgery, post-operative chemotherapy is generally considered the standard of care. Our case report demonstrates the potential benefit of neoadjuvant concurrent chemoradiotherapy prior to surgery for a malignant gastric neuroendocrine tumor. While radiotherapy has been demonstrated to possibly provide a survival benefit in the treatment of GI neuroendocrine tumors, its use in treatment, particularly neoadjuvantly, needs to be further assessed.

Keywords: gastric; neuroendocrine cancer; radiation therapy.

Figure 1. Radiation Treatment Plans

Radiation treatment plans, including gross tumor and regional nodal areas, on axial images. The upper image is the initial radiation treatment plan to 45 Gy in 25 fractions (yellow line). The green line is 95% of the prescription dose. The lower image is the re-simulation radiation plan that was not treated. The green line is 95% of the prescription dose. A 5.4 Gy boost plan was sequentially delivered.

Figure 2. Magnetic Resonance Images

Imaging from pre- and post-treatment. A) A T1 post-contrast MRI shows a large gastric mass with heterogeneous borders, which is 16.7 cm x 14.1 cm (blue arrows). B) A T1 post-contrast MRI after chemoradiation shows an improvement in gastric mass (blue arrows) with the ability to visualize bowel. C) A T1 post-contrast MRI after surgery showing no evidence of disease (blue arrows).