Introduction
Treatment for advanced colorectal cancer (CRC) has evolved over the years, particularly recently with the addition of novel targeted agents to chemotherapy. There are now several treatment combinations and treatment sequences from which patients can benefit under a continuum of care. This case describes a patient with metastatic CRC (mCRC) who initially received upfront capecitabine-oxaliplatin with bevacizumab. Due to poor disease response, she was switched to another cytotoxic combination with a targeted agent and has demonstrated a response.
Presentation and disease course
The patient is a 63-year-old female, with good functional status, who presented to the clinic in February 2014 with right upper quadrant pain. Upon further investigation, she was found to have stage IV CRC with multiple metastatic liver lesions. The tumour tested positive for KRAS mutation. At the time of diagnosis, the tumour was deemed unsuitable for resection and, consequently, the patient was offered combination cytotoxic chemotherapy with the targeted biological agent bevacizumab. The patient initially requested foregoing bevacizumab treatment to avoid the potential side effect of bleeding. She also requested foregoing a convenient regimen and consequently underwent three cycles of capecitabine with oxaliplatin, or XELOX (capecitabine, 1,400 mg twice a day from days 1 to 14; oxaliplatin, 170 mg given every 3 weeks) as an outpatient.
A follow-up positron emission tomography-computed tomography (PET-CT) scan showed only minimal tumour response (Figure), and her carcinoembryonic antigen (CEA) level had increased from the pretreatment level of 130 ng/mL to 190 ng/mL. The patient agreed to add bevacizumab (350 mg/cycle, given every 3 weeks) to XELOX at the fourth cycle. After a total of six cycles of XELOX, however, only a small decrease in CEA was seen, Second-line treatment options with other chemotherapy combinations were discussed with the patient, and she continued to stipulate a preference for outpatient treatment. From July 2014, the patient received irinotecan (260 mg) with the addition of the targeted agent aflibercept (200 mg/cycle, given every 2 weeks) to optimize tumour response. Capecitabine was not used because she had thrombocytopenia during the XELOX regimen.
The CEA level decreased to 30 ng/mL at the third cycle of second-line therapy, and to 13.3 ng/mL after the sixth cycle. Furthermore, following the sixth cycle, her tumour responded with marked decrease in size and in fluorodeoxyglucose (FDG)uptake of liver lesions (Figure). The patient developed neutropenia (but no fever); otherwise, she tolerated her treatment well. She had earlier received granulocyte colony-stimulating factor (G-CSF) for chemotherapy support.
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