RECURRENT RECTAL ADENOCARCINOMA WITH KRAS MUTATION POST-MFOLFOX6/BEVACIZUMAB REMISSION: A CASE REPORT
2 Department of Radiation and Clinical Oncology, National Hospital, Abuja
3 Department of Radiation and Clinical Oncology, Usmanu Danfodiyo University, Sokoto
4 Department of Radiation and Clinical Oncology, University College Hospital, Ibadan
5 Department of Obstetrics and Gynaecology, Ahmadu Bello University Teaching Hospital, Zaria, Nigeria.
6 Department of Surgery, Usmanu Danfodiyo University Teaching Hospital (UDUTH), Sokoto, Nigeria
7 Department of Histo-Pathology, Usmanu Danfodiyo University Teaching Hospital (UDUTH), Sokoto, Nigeria
8 Department of Radiation and Clinical Oncology, Ahmadu Bello University Teaching Hospital, Zaria
* Corresponding author: ytukur06@gmail.com
Abstract
Background: This case report elucidates the clinical trajectory of a 41-year-old male diagnosed with low rectal adenocarcinoma, further complicated by pulmonary metastases, harboring a KRAS mutation, and characterized by microsatellite stability.
Case Presentation: This patient demonstrated a significant and favorable response to neoadjuvant chemotherapy with a modified FOLFOX6 (mFOLFOX6) regimen in combination with bevacizumab, an anti-VEGF monoclonal antibody. This therapeutic intervention culminated in a complete remission, meticulously confirmed through Positron Emission Tomography/Computed Tomography (PET/CT) imaging. Subsequently, the patient was transitioned to a maintenance therapy protocol involving intermittent cycles of the same regimen to consolidate the achieved remission. However, after a six-month period of maintenance therapy, the patient experienced metastatic recurrence, unequivocally identified by the emergence of Fluorodeoxyglucose-avid lesions in the lungs, mesenteric nodes, and left adrenal gland.
Biopsies of the mesenteric and adrenal lesions pathologically confirmed adenocarcinoma, exhibiting an identical KRAS mutation and microsatellite stability profile to the primary tumor, strongly indicating disease progression rather than the manifestation of a new primary malignancy. The patient was subsequently initiated on a regimen of bevacizumab and capecitabine as salvage therapy, and the patient was radiotherapy or surgery naive which provides an opportunity to further explore alternative treatment strategies in this complex scenario.
Conclusion: This case underscores the inherent challenges in the clinical management of advanced rectal cancer, specifically highlighting the potential for acquired resistance to anti-angiogenic therapies such as bevacizumab, despite an initial robust response. Furthermore, it emphasizes the critical importance of vigilant and continuous monitoring for disease recurrence, even in patients who have achieved complete remission following first-line treatment strategies.
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