How should I manage a patient with FAP who has developed colorectal cancer?

Management of a patient with familial adenomatous polyposis (FAP) who has developed colorectal cancer requires a multidisciplinary approach integrating surgical, oncological, and genetic considerations. First-line treatment typically involves surgical resection of the colorectal cancer, often necessitating total proctocolectomy with ileal pouch-anal anastomosis or colectomy with ileorectal anastomosis depending on tumour location, extent of polyposis, and patient factors to reduce cancer risk and manage existing malignancy ¹. Preoperative systemic anti-cancer therapy may be considered for locally advanced tumours (e.g., cT4 stage) to improve resectability ¹.

Given the high risk of synchronous and metachronous tumours in FAP, comprehensive staging with CT imaging and serum carcinoembryonic antigen (CEA) measurement is essential for detecting local and distant metastases to guide treatment planning ¹. Postoperative adjuvant chemotherapy regimens such as CAPOX or FOLFOX are recommended for stage III disease, tailored to histopathology and patient factors ¹.

Patients should be managed within a multidisciplinary team including colorectal surgeons, oncologists, geneticists, and specialist nurses to ensure coordinated care and genetic counselling for the patient and at-risk relatives, as FAP is an inherited condition with implications for family screening ¹ (Kyriakidis et al., 2023). Genetic testing and counselling are critical to confirm diagnosis and guide surveillance for extracolonic manifestations (Lauricella et al., 2024).

Follow-up after potentially curative surgery should include regular surveillance with CEA and CT scans for at least 3 years to detect recurrence or metastases early ¹. Patients should be informed about possible postoperative complications such as low anterior resection syndrome and offered supportive treatments as needed ¹.

Recent literature emphasizes the importance of individualized treatment plans considering the aggressive nature of colorectal cancer in FAP and the need for lifelong surveillance for other associated malignancies (Kyriakidis et al., 2023; Lauricella et al., 2024). Emerging approaches include consideration of targeted therapies and novel systemic treatments, although these remain under investigation (Kyriakidis et al., 2023).