COMPLETE RESPONSE TO IMMUNOTHERAPY FOR MMR-DEFICIENT RECURRENT COLON CANCER: A CASE REPORT
Abdullah Bin Zubair*, Himani Bhatt, Kristen K. Rumer, Kellie L. Mathis
colon rectal surgery, Mayo Clinic Minnesota, Rochester, MN
Introduction:
We present a case report of a recurrent colon cancer successfully treated with immunotherapy, radiation and surgery.
Case Presentation:
A 71-year-old female presented with an 8cm cecal mass invading the right abdominal wall seen on CT scan. Labs were remarkable for an iron deficiency anemia and a serum CEA of 98. Colonoscopy confirmed a poorly differentiated adenocarcinoma. Further CT imaging excluded metastatic spread. She underwent a right hemicolectomy with en bloc resection of a portion of the right anterior abdominal wall, and pathology revealed a 10-cm x 9.5-cm x 9.0-cm poorly differentiated high-grade colon adenocarcinoma with focal signet ring features. Zero of 25 lymph nodes retrieved were involved. MLH1 and PMS2 expression were deficient on IHC, consistent with microsatellite unstable disease. She was discharged on the 3rd postoperative day after an uncomplicated recovery.
One month later, she was diagnosed with an enterocutaneous fistula. CT showed a 5.8 cm mass in the RLQ and a biopsy revealed poorly differentiated metastatic adenocarcinoma. She started FOLFOX therapy but serial CT scans showed that the mass continued to grow and was abutting the iliac bone. (Figure 1a) She was switched to pembrolizumab due to the MMR deficient tumor. Repeat imaging showed significant regression. (Figure 1b)
She then started neoadjuvant chemoradiation followed by surgical resection and intraoperative radiation to the tumor bed and iliac bone. There was no residual tumor in the resection specimen. She recovered without complications, continued pembrolizumab for 6 months in the adjuvant setting, and is now 4 years disease-free.
Conclusion:
We report a case of a rapidly enlarging MMR-deficient recurrent colon cancer that responded well to immunotherapy, radiation and surgical resection with no evidence of recurrence for 4 years to date.
(Figure 1a) Before Pembrolizumab Therapy Tumour Abutting The Illiac Bone.
(Figure 1b) Post Pembrilizumab Therapy shows Tumor Showed Regression
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